Modelling extraction and separation of some alpha-transition elements from acidic media by synergic combinations of aromatic polyimines and micellar cationic exchangers

International Nuclear Information System (INIS)

Vitart, X.; Musikas, C.

1988-01-01

In this paper is emphasized, taking the extraction and separation by Dinonylnaphtalene sulfonic acid (HDMNS)of ruthenium-rhodium from a nitric acid media and nickel-cobalt from a sulfuric acid media as examples, the quantified chemical equilibria involved in order to elucidate the extraction mechanism. Reactions in aqueous media were investigated within three aspects: kinetics of formation, stability of metal complexes, ionic associations between complexes and mineral anions present in acidic media. This last point explains partly the selectivity of the system. The behaviour of HDNNS within extraction conditions, was studied leading to the structure of the micelle and to the quantification of equilibria involved (critical micelle concentration, polymerisation constant, etc...). Ligand extraction was studied previously to metal complexes extraction since the general mechanism of the system proceeds as a competitive extraction of cationic species in aqueous media (protonated forms of the free ligand, cationic metal complexes). The modelling of independent extraction of metals was used to predict numerically the behaviour of a multicomponent system where few metals are initially in aqueous media. These simulations are in accordance with experimental results

Electrolytic nature of aqueous sulfuric acid. 2. Acidity.

Science.gov (United States)

Fraenkel, Dan

2012-09-27

In part 1 of this study, I reported that the Debye-Hückel limiting law and the smaller-ion shell (SiS) model of strong electrolyte solutions fit nicely with the experimental mean ionic activity coefficient (γ(±)) of aqueous sulfuric acid as a function of concentration and of temperature when the acid is assumed to be a strong 1-3 electrolyte. Here, I report that the SiS-derived activity coefficient of H(+), γ(H(+)), of the 1-3 acid is comparable to that of aqueous HCl. This agrees with titration curves showing, as well-known, that sulfuric acid in water is parallel in strength to aqueous HCl. The calculated pH is in good accord with the Hammett acidity function, H(0), of aqueous sulfuric acid at low concentration, and differences between the two functions at high concentration are discussed and explained. This pH-H(0) relation is consistent with the literature showing that the H(0) of sulfuric acid (in the 1-9 M range) is similar to those of HCl and the other strong mineral monoprotic acids. The titration of aqueous sulfuric acid with NaOH does not agree with the known second dissociation constant of 0.010 23; rather, the constant is found to be ~0.32 and the acid behaves upon neutralization as a strong diprotic acid practically dissociating in one step. A plausible reaction pathway is offered to explain how the acid may transform, upon base neutralization, from a dissociated H(4)SO(5) (as 3H(+) and HSO(5)(3-)) to a dissociated H(2)SO(4) even though the equilibrium constant of the reaction H(+) + HSO(5)(3-) ↔ SO(4)(2-) + H(2)O, at 25 °C, is 10(-37) (part 1).

Layered Double Hydroxides as Effective Adsorbents for U(VI and Toxic Heavy Metals Removal from Aqueous Media

Directory of Open Access Journals (Sweden)

G. N. Pshinko

2013-01-01

Full Text Available Capacities of different synthesized Zn,Al-hydrotalcite-like adsorbents, including the initial carbonate [Zn4Al2(OH12]·CO3·8H2O and its forms intercalated with chelating agents (ethylenediaminetetraacetic acid (EDTA, diethylenetriaminepentaacetic acid (DTPA, and hexamethylenediaminetetraacetic acid (HMDTA and heat-treated form Zn4Al2O7, to adsorb uranium(VI and ions of toxic heavy metals have been compared. Metal sorption capacities of hydrotalcite-like adsorbents have been shown to correlate with the stability of their complexes with the mentioned chelating agents in a solution. The synthesized layered double hydroxides (LDHs containing chelating agents in the interlayer space are rather efficient for sorption purification of aqueous media free from U(VI irrespective of its forms of natural abundance (including water-soluble bi- and tricarbonate forms and from heavy metal ions. [Zn4Al2(OH12]·EDTA·nH2O is recommended for practical application as one of the most efficient and inexpensive synthetic adsorbents designed for recovery of both cationic and particularly important anionic forms of U(VI and other heavy metals from aqueous media. Carbonate forms of LDHs turned out to be most efficient for recovery of Cu(II from aqueous media with pH0≥7 owing to precipitation of Cu(II basic carbonates and Cu(II hydroxides. Chromate ions are efficiently adsorbed from water only by calcinated forms of LDHs.

Acetic acid extraction from aqueous solutions using fatty acids

NARCIS (Netherlands)

IJmker, H.M.; Gramblicka, M.; Kersten, Sascha R.A.; van der Ham, Aloysius G.J.; Schuur, Boelo

2014-01-01

A major challenge for production of acetic acid via bio-based routes is cost-effective concentration and purification of the acetic acid from the aqueous solutions, for which liquid–liquid extraction is a possible method. A main challenge in extraction of acetic acid from dilute aqueous solutions is

Kinetics and mechanism of the oxidation of uranium (IV) by hypochlorous acid in aqueous acidic perchlorate media

International Nuclear Information System (INIS)

Silverman, R.A.; Gordon, G.

1976-01-01

The oxidation of uranium(IV) by hypochlorous acid has been studied in aqueous sodium perchlorate--perchloric acid solutions. The reaction U 4 + + 2HOCl = UO 2 2 + + Cl 2 (aq) + 2H + proceeds appropriate to the rate law --d[U(IV)]/dt = k 0 . [U 4+ ][HOCl][H + ] -1 . At 25 0 and 3 M ionic strength, k 0 is 1.08 +- 0.07 sec -1 . Over the 1--25 0 temperature range, ΔH 2+ is 18.4 +- 0.1 kcal mole -1 , and ΔS 2+ is 3.1 +- 0.4 eu. The inverse hydrogen ion dependence of the rate law is explained by a rapid preequilibrium, in which a proton is lost from one of the reactants. A uranyl-like activated complex, [H 2 UO 2 Cl 3+ ] 2+ , is suggested, with one proton likely to be residing on each oxygen atom. Evidence is presented that the mechanism involves a two-electron transfer, with the intermediate chloride ion rapidly reacting with hypochlorous acid to form chlorine. The uranium(IV)-hypochlorous acid reaction plays an important role in the oxidation of uranium(IV) by aqueous chlorine solutions. The magnitude of this role was seriously underestimated by previous investigators

Effect of Aqueous Media on the Recovery of Scandium by Selective Precipitation

Directory of Open Access Journals (Sweden)

Bengi Yagmurlu

2018-05-01

Full Text Available This research presents a novel precipitation method for scandium (Sc concentrate refining from bauxite residue leachates and the effect of aqueous media on this triple-stage successive precipitation process. The precipitation pattern and the precipitation behavior of the constituent elements was investigated using different precipitation agents in three major mineral acid media, namely, H2SO4, HNO3, and HCl in a comparative manner. Experimental investigations showed behavioral similarities between HNO3 and HCl media, while H2SO4 media was different from them because of the nature of the formed complexes. NH4OH was found to be the best precipitation agent in every leaching media to remove Fe(III with low Sc co-precipitation. To limit Sc loss from the system, Fe(III removal was divided into two steps, leading to more than 90% of Fe(III removal at the end of the process. Phosphate concentrates were produced in the final step of the precipitation process with dibasic phosphates which have a strong affinity towards Sc. Concentrates containing more than 50% of ScPO4 were produced in each case from the solutions after Fe(III removal, as described. A flow diagram of the selective precipitation process is proposed for these three mineral acid media with their characteristic parameters.

Conformation of poly(γ-glutamic acid) in aqueous solution.

Science.gov (United States)

Muroga, Yoshio; Nakaya, Asami; Inoue, Atsuki; Itoh, Daiki; Abiru, Masaya; Wada, Kaori; Takada, Masako; Ikake, Hiroki; Shimizu, Shigeru

2016-04-01

Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε acidic media. © 2015 Wiley Periodicals, Inc.

Radiation-induced changes of liposomes and lecithin in non-aqueous media

International Nuclear Information System (INIS)

Nakazawa, T.; Nagatsuka, S.; Sakurai, T.

1981-01-01

Radiation-induced changes of lipids in non-aqueous media were studied to elucidate the process of radiation damage in biological membranes. The lipid peroxidation progressed linearly with increasing dose and decreasing dose rate of γ-irradiation in soyabean lecithin in chloroform. The fatty acid composition of lecithin also changed, especially in linoleic and linolenic acids. Lower dose rate radiation enhanced these changes in oxic condition. Lipid peroxidation was also shown in lipids extracted from irradiated liposomes or in liposomes prepared from irradiated lecithin in chloroform. The dose-dependent glucose efflux was seen in liposomes prepared from irradiated lecithin in chloroform. These results indicate that the peroxidation of lipid molecules might cause radiation damage to the membrane conformation. (author)

Calcium isotope fractionation in liquid chromatography with benzo-18-crown-6 resin in aqueous hydrobromic acid medium

International Nuclear Information System (INIS)

Sato, Takuya; Oi, Takao

2015-01-01

Liquid chromatography operated in a breakthrough mode was employed to study calcium isotope fractionation in the aqueous hydrobromic acid medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of calcium was observed in the frontal part of respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10 -3 . The observed isotope fractionation coefficient was dependent on the concentration of hydrobromic acid in the calcium feed solution; a higher HBr concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass-dependent, indicating that they mostly came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion. Chromatography operated in aqueous HBr media is a better system of Ca isotope separation than that operated in aqueous HCl media. (author)

Deep Eutectic Solvent Aqueous Solutions as Efficient Media for the Solubilization of Hardwood Xylans.

Science.gov (United States)

Morais, Eduarda S; Mendonça, Patrícia V; Coelho, Jorge F J; Freire, Mara G; Freire, Carmen S R; Coutinho, João A P; Silvestre, Armando J D

2018-02-22

This work contributes to the development of integrated lignocellulosic-based biorefineries by the pioneering exploitation of hardwood xylans by solubilization and extraction in deep eutectic solvents (DES). DES formed by choline chloride and urea or acetic acid were initially evaluated as solvents for commercial xylan as a model compound. The effects of temperature, molar ratio, and concentration of the DES aqueous solutions were evaluated and optimized by using a response surface methodology. The results obtained demonstrated the potential of these solvents, with 328.23 g L -1 of xylan solubilization using 66.7 wt % DES in water at 80 °C. Furthermore, xylans could be recovered by precipitation from the DES aqueous media in yields above 90 %. The detailed characterization of the xylans recovered after solubilization in aqueous DES demonstrated that 4-O-methyl groups were eliminated from the 4-O-methylglucuronic acids moieties and uronic acids (15 %) were cleaved from the xylan backbone during this process. The similar M w values of both pristine and recovered xylans confirmed the success of the reported procedure. DES recovery in four additional extraction cycles was also demonstrated. Finally, the successful extraction of xylans from Eucalyptus globulus wood by using aqueous solutions of DES was demonstrated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chitosan-caffeic acid-genipin films presenting enhanced antioxidant activity and stability in acidic media.

Science.gov (United States)

Nunes, Cláudia; Maricato, Élia; Cunha, Ângela; Nunes, Alexandra; da Silva, José A Lopes; Coimbra, Manuel A

2013-01-02

The use of chitosan films has been limited due to their high degradability in aqueous acidic media. In order to produce chitosan films with high antioxidant activity and insoluble in acid solutions caffeic acid was grafted to chitosan by a radical mechanism using ammonium cerium (IV) nitrate (60 mM). Genipin was used as cross-linker. This methodology originated films with 80% higher antioxidant activity than the pristine film. Also, these films only lost 11% of their mass upon seven days immersion into an aqueous solution at pH 3.5 under stirring. The films surface wettability (contact angle 105°), mechanical properties (68 MPa of tensile strength and 4% of elongation at break), and thermal stability for temperatures lower than 300 °C were not significantly influenced by the covalent linkage of caffeic acid and genipin to chitosan. Due to their characteristics, mainly higher antioxidant activity and lower solubility, these are promising materials to be used as active films. Copyright © 2012 Elsevier Ltd. All rights reserved.

Oxytetracycline recovery from aqueous media using computationally designed molecularly imprinted polymers.

Science.gov (United States)

Rodríguez-Dorado, Rosalía; Carro, Antonia M; Chianella, Iva; Karim, Kal; Concheiro, Angel; Lorenzo, Rosa A; Piletsky, Sergey; Alvarez-Lorenzo, Carmen

2016-09-01

Polymers for recovery/removal of the antimicrobial agent oxytetracycline (OTC) from aqueous media were developed with use of computational design and molecular imprinting. 2-Hydroxyethyl methacrylate, 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and mixtures of the two were chosen according to their predicted affinity for OTC and evaluated as functional monomers in molecularly imprinted polymers and nonimprinted polymers. Two levels of AMPS were tested. After bulk polymerization, the polymers were crushed into particles (200-1000 μm). Pressurized liquid extraction was implemented for template removal with a low amount of methanol (less than 20 mL in each extraction) and a few extractions (12-18 for each polymer) in a short period (20 min per extraction). Particle size distribution, microporous structure, and capacity to rebind OTC from aqueous media were evaluated. Adsorption isotherms obtained from OTC solutions (30-110 mg L(-1)) revealed that the polymers prepared with AMPS had the highest affinity for OTC. The uptake capacity depended on the ionic strength as follows: purified water > saline solution (0.9 % NaCl) > seawater (3.5 % NaCl). Polymer particles containing AMPS as a functional monomer showed a remarkable ability to clean water contaminated with OTC. The usefulness of the stationary phase developed for molecularly imprinted solid-phase extraction was also demonstrated. Graphical Abstract Selection of functional monomers by molecular modeling renders polymer networks suitable for removal of pollutants from contaminated aqueous environments, under either dynamic or static conditions.

Microwave-assisted synthesis of bio-active heterocycles in aqueous media

KAUST Repository

Polshettiwar, Vivek; Varma, Rajender S.

2010-01-01

Synthesis of bio-active heterocycles and fine chemicals in aqueous media are one of the best solutions for the development of green and sustainable protocols. To illustrate the advantages of aqueous MW chemistry in heterocycle synthesis

Solvent extraction of hafnium(IV) by dinonylnaphthalene sulfonic acid from mixed aqueous-organic media

International Nuclear Information System (INIS)

Hala, J.; Piperkovova, H.

1979-01-01

The extraction of hafnium(IV) by heptane and toluene solutions of dinonylnaphthalene sulfonic acid (HD) from mixed aqueous-organic solutions has been studied. Alcohols, ketones, carboxylic acids, cyclic ethers, dimethylsulfoxide and dimethylformamide were used as the organic component of the mixed phase. Methanol, ethanol, formic acid and dioxane increased the extractability of Hf(IV) whereas other solvents showed only an antagonistic effect. The results were discussed from the point of view of the changes in micellar structure of HD, and compared with the uptake of Hf(IV) by resinous cation exchangers. The solubilization by HD of alcohols, carboxylic acids and dimethylsulfoxide was demonstrated by using the corresponding 14 C and 35 S labelled compounds. (author)

Atmospheric-pressure air microplasma jets in aqueous media for the inactivation of Pseudomonas fluorescens cells

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xianhui; Yang, Si-ze [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Dongping [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); Song, Ying [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Sun, Yue [School of Physics, Changchun University of Science and Technology, Changchun 130022 (China)

2013-05-15

The hollow fiber-based cold air microplasma jet array running at atmospheric pressure has been designed to inactivate Pseudomonas fluorescens (P. fluorescens) cells in vitro in aqueous media. The influences of electrode configurations, air flow rate, and applied voltage on the discharge characteristics of the single microplasma jet operating in aqueous media are presented, and the bactericidal efficiency of the hollow fibers-based and large-volume microplasma jet array is reported. Optical emission spectroscopy is utilized to identify excited species during the antibacterial testing of plasma in solutions. These well-aligned and rather stable air microplasma jets containing a variety of short-lived species, such as OH and O radicals and charged particles, are in direct contact with aqueous media and are very effective in killing P. fluorescens cells in aqueous media. This design shows its potential application for atmospheric pressure air plasma inactivation of bacteria cells in aqueous media.

Corrosion inhibitors for neutral aqueous media based on the products on sugar cane processing. 1.Furfural derivatives as inhibitors

International Nuclear Information System (INIS)

Ledovskikh, V.M.; Kamekho Khinnebra, Kh.Kh.

1993-01-01

A series of carboxy-, nitrogen- and nitroderivaties of furfural - the main product of sugar cane processing (furancasboxylic acid, 5-nitrofurancarboxylic acid and its salts, furfurine, furfurylamine) was studied as inhibitors of iron and copper, corrosion in aqueous-salt media. Nitrofuroates of sodium and ammonium, which decelerate anode process, intensity cathode one and provide the stable passive state, are considered to be the most effective

Lewis Acid Pairs for the Activation of Biomass-derived Oxygenates in Aqueous Media

Energy Technology Data Exchange (ETDEWEB)

Roman, Yuriy [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2015-09-14

The objective of this project is to understand the mechanistic aspects behind the cooperative activation of oxygenates by catalytic pairs in aqueous media. Specifically, we will investigate how the reactivity of a solid Lewis acid can be modulated by pairing the active site with other catalytic sites at the molecular level, with the ultimate goal of enhancing activation of targeted functional groups. Although unusual catalytic properties have been attributed to the cooperative effects promoted by such catalytic pairs, virtually no studies exist detailing the use heterogeneous water-tolerant Lewis pairs. A main goal of this work is to devise rational pathways for the synthesis of porous heterogeneous catalysts featuring isolated Lewis pairs that are active in the transformation of biomass-derived oxygenates in the presence of bulk water. Achieving this technical goal will require closely linking advanced synthesis techniques; detailed kinetic and mechanistic investigations; strict thermodynamic arguments; and comprehensive characterization studies of both materials and reaction intermediates. For the last performance period (2014-2015), two technical aims were pursued: 1) C-C coupling using Lewis acid and base pairs in Lewis acidic zeolites. Tin-, zirconium-, and hafnium containing zeolites (e.g., Sn-, Zr-, and Hf-Beta) are versatile solid Lewis acids that selectively activate carbonyl functional groups. In this aim, we demonstrate that these zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions. 2) One-pot synthesis of MWW zeolite nanosheets for activation of bulky substrates. Through

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)

Study of radium extraction mechanisms from scales by leaching in different acidic and alkaline media

International Nuclear Information System (INIS)

Al-Masri, M. S.; Gafar, M.; Al-Kurdi, H.

2002-07-01

The present report shows the results of leaching experiments for scales containing naturally occuring radioactive materials using different acidic and alkaline media. The obtained result can be used for defining the method of safe disposal of such waste. Leaching solutions used in this study were distilled water, mineral acids (sulpharic acid, hydrochloric acid and nitric acid), sodium, potassium hydroxides, ammonium oxalate EDTA, sodium carbonate, potassium acetate, and a mixture of potassium chloride and hydrochloric acid. The results have shown that the extraction ratio of radium-226, the most abundant isotope in scales, is very low and even negligible using all different media. This indicates that all scales produced in Syrian oil fields do not require any chemical preparation before disposal. In addition, the effect of both stirring time of phrases and concentration of leaching media that may affect the radium transfer process from solid phase to aqueous phase have been investigated were no measurable amount being observed in the leachate. (author)

Aqueous Boric acid injection facility of PWR type reactor

International Nuclear Information System (INIS)

Matsuoka, Tsuyoshi; Iwami, Masao.

1996-01-01

If a rupture should be caused in a secondary system of a PWR type reactor, pressure of a primary coolant recycling system is lowered, and a back flow check valve is opened in response to the lowering of the pressure. Then, low temperature aqueous boric acid in the lower portion of a pressurized tank is flown into the primary coolant recycling system based on the pressure difference, and the aqueous boric acid reaches the reactor core together with coolants to suppress reactivity. If the injection is continued, high temperature aqueous boric acid in the upper portion boils under a reduced pressure, further urges the low temperature aqueous boric acid in the lower portion by the steam pressure and injects the same to the primary system. The aqueous boric acid stream from the pressurized tank flowing by self evaporation of the high temperature aqueous boric acid itself is rectified by a rectifying device to prevent occurrence of vortex flow, and the steam is injected in a state of uniform stream. When the pressure in the pressurized tank is lowered, a bypass valve is opened to introduce the high pressure fluid of primary system into the pressurized tank to keep the pressure to a predetermined value. When the pressure in the pressurized tank is elevated to higher than the pressure of the primary system, a back flow check valve is opened, and high pressure aqueous boric acid is flown out of the pressurized tank to keep the pressure to a predetermined value. (N.H.)

Solvation thermodynamics of L-cystine, L-tyrosine, and L-leucine in aqueous-electrolyte media

Science.gov (United States)

Roy, Sanjay; Guin, Partha Sarathi; Mahali, Kalachand; Dolui, Bijoy Krishna

2017-12-01

Solubilities of L-cystine, L-tyrosine, and L-leucine in aqueous NaCl media at 298.15 K have been studied. Indispensable and related solvent parameters such as molar mass, molar volume, etc., were also determined. The results are used to evaluate the standard transfer Gibbs free energy, cavity forming enthalpy of transfer, cavity forming transfer Gibbs free energy and dipole-dipole interaction effects during the course of solvation. Various weak interactions involving solute-solvent or solvent-solvent molecules were characterized in order to find their role on the solvation of these amino acids.

Preparation of SBA-15-PAMAM as a Nano Adsorbent for Removal of Acid Red 266 from Aqueous Media: Batch Adsorption and Equilibrium Studies

Directory of Open Access Journals (Sweden)

Maryam Mirzaie

2017-12-01

Full Text Available The purpose of the present study was to increase the adsorption capacity of SBA-15 for acidic dyes. Ordered mesoporous silica SBA-15 was successfully synthesized and functionalized by polyamidoamine (PAMAM dendrimer to develop an efficient anionic dye adsorbent. The prepared materials were characterized by field emission scanning electron microscope (FE-SEM, Fourier transforms infrared spectroscope (FT-IR and N2 adsorption–desorption analysis. The study was concocted in the Science and Research Branch of Islamic Azad University of Tehran, Iran in 2016. The produced adsorbent (SBA-15-Den was applied for the removal of Acid Red 266 (AR266 from aqueous media. The effects of various operational parameters including solution pH, adsorbent dosage, contact time, and temperature on removal of AR266 using SBA-15-Den were investigated in batch adsorption mode. Within the optimum conditions, SBA-15-Den exhibited an excellent adsorptive capability of 1111.11 mg/g. Equilibrium data were best described by Langmuir model (R2 > 0.98 completely.

Aqueous-Phase Acetic Acid Ketonization over Monoclinic Zirconia

Energy Technology Data Exchange (ETDEWEB)

Cai, Qiuxia [Institute for Integrated Catalysis, Pacific Northwest; College; Lopez-Ruiz, Juan A. [Institute for Integrated Catalysis, Pacific Northwest; Cooper, Alan R. [Institute for Integrated Catalysis, Pacific Northwest; Wang, Jian-guo [College; Albrecht, Karl O. [Institute for Integrated Catalysis, Pacific Northwest; Mei, Donghai [Institute for Integrated Catalysis, Pacific Northwest

2017-12-13

The effect of aqueous phase on the acetic acid ketonization over monoclinic zirconia has been investigated using first-principles based density functional theory (DFT) calculations. To capture the aqueous phase chemistry over the solid zirconia catalyst surface, the aqueous phase is represented by 111 explicit water molecules with a liquid water density of 0.93 g/cm3 and the monoclinic zirconia is modeled by the most stable surface structure . The dynamic nature of aqueous phase/ interface was studied using ab initio molecular dynamics simulation, indicating that nearly half of the surface Zr sites are occupied by either adsorbed water molecules or hydroxyl groups at 550 K. DFT calculations show that the adsorption process of acetic acid from the liquid water phase to the surface is nearly thermodynamically neutral with a Gibbs free energy of -2.3 kJ/mol although the adsorption strength of acetic acid on the surface in aqueous phase is much stronger than in vapor phase. Therefore it is expected that the adsorption of acetic acid will dramatically affects aqueous phase ketonization reactivity over the monoclinic zirconia catalyst. Using the same ketonization mechanism via the β-keto acid intermediate, we have compared acetic acid ketonization to acetone in both vapor and aqueous phases. Our DFT calculation results show although the rate-determining step of the β-keto acid formation via the C-C coupling is not pronouncedly affected, the presence of liquid water molecules will dramatically affect dehydrogenation and hydrogenation steps via proton transfer mechanism. This work was financially supported by the United States Department of Energy (DOE)’s Bioenergy Technologies Office (BETO) and performed at the Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program national laboratory operated for DOE by Battelle Memorial Institute. Computing time and advanced catalyst characterization use was granted by a user proposal at the William R. Wiley

Study of free acidity determinations in aqueous solution

International Nuclear Information System (INIS)

Kergreis, A.

1966-04-01

The object of this work is the study of the principal methods which can be applied to the measurement of 'free' acidity. In the first part, we define the various types of acidity which can exist in aqueous solution; then, after having studied some hydrolysis reactions, we compare the value of the neutralisation pH of the hydrated cation and that of the precipitation of the hydroxide. In the second part we have started to study the determination of the acidity of an aqueous solution. After having rapidly considered the 'total' acidity determination, we deal with the problem of the 'free' acidity titration. We have considered in particular certain methods: extrapolation of the equivalent point, colorimetric titrations with or without a complexing agent, and finally the use of ion-exchange resins with mixed aqueous and solvent solutions. (author) [fr

Formation and reactions of radical cations of substituted benzenes in aqueous media

International Nuclear Information System (INIS)

Holcman, J.

1977-08-01

Radical cations of anisole, methylated benzenes, ethylbenzene, isopropylbenzene, tert-butylbenzene and N,N-dimethylaniline were studied in aqueous media by pulse radiolytic technique. Absorption spectra and reaction kinetics of the radical cations were recorded. The radical cations are formed from the corresponding OH adducts by the elimination of OH - , either by a simple dissociation or by an acid catalyzed reaction. The rate constants of the formation of the radical cations and their reactions with water, OH - and Fe 2+ , or the reaction of a proton loss, were measured. The rate constants for the reaction with water and OH - , together with the rate constants for the dissociation of the OH adducts, are correlated with the ionization potential of the parent compound. These correlations offer a possibility of predicting the acid-base properties of radical cations of substituted benzenes, or the estimation of their ionization potential. (author)

Reductive amination with zinc powder in aqueous media

Directory of Open Access Journals (Sweden)

Giovanni B. Giovenzana

2011-08-01

Full Text Available Zinc powder in aqueous alkaline media was employed to perform reductive amination of aldehydes with primary amines. The corresponding secondary amines were obtained in good yields along with minor amounts of hydrodimerization byproducts. The protocol is a green alternative to the use of complex hydrides in chlorinated or highly flammable solvents.

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.

Dissolution of metal and metal oxide nanoparticles in aqueous media

International Nuclear Information System (INIS)

Odzak, Niksa; Kistler, David; Behra, Renata; Sigg, Laura

2014-01-01

The dissolution of Ag (citrate, gelatin, polyvinylpyrrolidone and chitosan coated), ZnO, CuO and carbon coated Cu nanoparticles (with two nominal sizes each) has been studied in artificial aqueous media, similar in chemistry to environmental waters, for up to 19 days. The dissolved fraction was determined using DGT (Diffusion Gradients in Thin films), dialysis membrane (DM) and ultrafiltration (UF). Relatively small fractions of Ag nanoparticles dissolved, whereas ZnO dissolved nearly completely within few hours. Cu and CuO dissolved as a function of pH. Using DGT, less dissolved Ag was measured compared to UF and DM, likely due to differences in diffusion of organic complexes. Similar dissolved metal concentrations of ZnO, Cu and CuO nanoparticles were determined using DGT and UF, but lower using DM. The results indicate that there is a need to apply complementary techniques to precisely determine dissolution of nanoparticles in aqueous media. - Highlights: • Three different techniques used simultaneously to measure NPs dissolution. • ZnO-NPs are the most soluble, followed by CuO-NPs, carbon coated Cu-NPs and Ag-NPs. • Dissolution is an important process affecting the fate of nanoparticles. • Complementary techniques are needed to precisely determine dissolution of NPs. - Dissolution of several types of nanoparticles was examined in aqueous media using three complementary techniques

Smart surfaces with switchable superoleophilicity and superoleophobicity in aqueous media: Toward controllable oil/water separation

KAUST Repository

Zhang, L.

2012-02-01

Advanced materials with surfaces that have controllable oil wettability when submerged in aqueous media have great potential for various underwater applications. Here we have developed smart surfaces on commonly used materials, including non-woven textiles and polyurethane sponges, which are able to switch between superoleophilicity and superoleophobicity in aqueous media. The smart surfaces are obtained by grafting a block copolymer, comprising blocks of pH-responsive poly(2-vinylpyridine) and oleophilic/hydrophobic polydimethylsiloxane (i.e., P2VP-b-PDMS) on these materials. The P2VP block can alter its wettability and its conformation via protonation and deprotonation in response to the pH of the aqueous media, which provides controllable and switchable access of oil by the PDMS block, resulting in the switchable surface oil wettability in the aqueous media. On the other hand, the high flexibility of the PDMS block facilitates the reversible switching of the surface oil wettability. As a proof of concept, we also demonstrate that materials functionalized with our smart surfaces can be used for highly controllable oil/water separation processes.

Propargylamine-isothiocyanate reaction: efficient conjugation chemistry in aqueous media

DEFF Research Database (Denmark)

Viart, Helene Marie-France; Larsen, T. S.; Tassone, Chiara

2014-01-01

A coupling reaction between secondary propargyl amines and isothiocyanates in aqueous media is described. The reaction is high-yielding and affords cyclized products within 2-24 h. A functionalized ether lipid was synthesized in 8 steps, formulated as liposomes with POPC and conjugated to FITC un...

Synthesis and functionalization of dextran-based single-chain nanoparticles in aqueous media

OpenAIRE

Gracia R.; Marradi M.; Cossío U.; Benito A.; Pérez-San Vicente A.; Gómez-Vallejo V.; Grande H.-J.; Llop J.; and Loinaz I.

2017-01-01

Water-dispersible dextran-based single-chain polymer nanoparticles (SCPNs) were prepared in aqueous media and under mild conditions. Radiolabeling of the resulting biocompatible materials allowed the study of lung deposition of aqueous aerosols after intratracheal nebulization by means of single-photon emission computed tomography (SPECT), demonstrating their potential use as imaging contrast agents.

Thermodynamic properties of aqueous solutions with citrate ions. Compressibility studies in aqueous solutions of citric acid

International Nuclear Information System (INIS)

Apelblat, Alexander; Korin, Eli; Manzurola, Emanuel

2013-01-01

Highlights: • Over a wide range of concentrations and temperatures sound velocities were measured in aqueous solutions of citric acid. • Compressibility properties of citric acid solutions are thermodynamically characterized. • Changes in the structure of water when citric acid is dissolved are discussed. -- Abstract: Sound velocities in aqueous solutions of citric acid were measured from 15 °C to 50 °C in 5 °C intervals, within the 0.1 mol · kg −1 to 5.0 mol · kg −1 concentration range. These sound velocities served to evaluate the isentropic and isothermal compressibilities, the apparent molar compressibilities, the isochoric thermal pressure coefficients, changes of the cubic expansion coefficients with pressure at constant temperature, the changes of heat capacities with volume and hydration numbers of citric acid in aqueous solutions

Volumetric properties of itaconic acid aqueous solutions

International Nuclear Information System (INIS)

Nisenbaum, Alexander; Apelblat, Alexander; Manzurola, Emanuel

2012-01-01

Highlights: ► Densities of itaconic acid aqueous solutions in a wide range of concentrations and temperatures. ► The apparent molar volumes and the cubic expansion coefficients. ► The derivatives of isobaric heat capacities with respect to pressure. ► Changes in the structure of water when itaconic acid is dissolved. - Abstract: Densities of itaconic acid aqueous solutions were measured at 5 K intervals from T = (278.15 to 343.15) K. From the determined densities, the apparent molar volumes, the cubic expansion coefficients and the second derivatives of volume with respect to temperature which are interrelated with the derivatives of isobaric heat capacities with respect to pressure were evaluated. These derivatives were qualitatively correlated with the changes in the structure of water when itaconic acid is dissolved in it.

Some aspects of synergistic extraction of actinides and lanthanides from mixed aqueous-organic media

International Nuclear Information System (INIS)

Shukla, J.P.; Subramanian, M.S.

1981-01-01

Various aspects of the synergistic extraction and separation of actinides and lanthanides from mixed aqueous-organic solutions (polar media) have been reviewed. Notable recent developments as well as its current status in solvent extraction systems where the aqueous acidic phase contains an organic solvent which is completely miscible with water, are presented briefly. In general, extraction increases in the presence of an organic component. The less polar the additive, the higher is the tendency to form neutral metal complexes which ultimately brings about an increase in the extraction. In a polar media, synergism has mostly been observed, though antagonism is not uncommon. An attempt has been made to classify the factors that play an important role in polar phase extractions. Also, their influence particularly on the extractability of actinides and lanthanides is discussed. The discussion is limited to the factors affecting the extraction equilibria, effect of dielectric constant of the polar medium, solvation of the extracting agent and to the composition and stability of the metal complex in the organic phase. Hydroxyl (OHsup(-)) bearing organic additives, e.g. alcohols, and solvents not containing the hydroxyl group such as acetone, dimethylsulphoxide, tetrahydrofuran, amides and acetonitrile etc. are the two major classes of organic additives considered in these studies. Generally, synergistic effect in extraction of the ion-association (TBP, TOPO, sulphoxides etc.) or anion exchange (amines etc.) type is relatively more pronounced compared to other extractions. A tabular summary concerning extraction of actinides and lanthanides from polar media is appended for ready reference. (author)

XAS Investigation of bio-relevant cobalt complexes in aqueous media

International Nuclear Information System (INIS)

Bresson, C.; Lamouroux, C.; Esnouf, S.; Solari, P.L.; Den Auwer, C.

2006-01-01

Cobalt is an essential element of biological cycles involved in numerous metallo-biomolecules, but it becomes a toxic element at high concentration or a radio-toxic element because of its use in the nuclear industry. 'Molecular speciation' in biological media is an essential prerequisite to evaluate its chemical behaviour as well as its toxic or beneficial effects. In this scheme, we have focused on the coordination properties of the thiol-containing amino acid cysteine (Cys) and the pseudo-peptide N-(2-mercapto-propionyl) glycine (MPG) towards the Co 2+ cation in aqueous media. XAS at the Co K edge and traditional spectroscopic techniques have been coupled in order to structurally characterize the cobalt coordination sphere. Oxidation states and geometries of the bis- and tris-cysteinato Co(III) complexes are in agreement with the literature data. In addition, bond lengths between the metallic centre and the donor atoms have been determined. The structure of a new dimeric N-(2-mercapto-propionyl) glycinato Co(II) complex in solution is also reported. The coordination of MPG to Co(II) through the thiolate and carboxylate functions is ascertained. This work provides fundamental structural information about bio-relevant complexes of cobalt, which will contribute to our understanding of the chemical behaviour and the biological role of this radionuclide. (authors)

Synthesis and characterization of ferrous phosphate (vivianite) and its behavior in aqueous media

International Nuclear Information System (INIS)

Diaz F, J.C.

2003-01-01

The synthesis and characterization of materials that can be useful in Environmental Chemistry is very important because their characteristics are exposed and its behavior in chemical phenomena as the sorption in aqueous media is understand to use it in the human being benefit. With the object of using, in a future, the octa hydrated ferrous phosphate (vivianite) as a potential candidate for matrix confinement in contention walls for the storage of radioactive waste of long half life, it was synthesized and it characterized physico chemically and their properties of surface of this compound were evaluated. Presently work was carried out the synthesis and structural characterization of the iron phosphate II by infrared spectroscopy with having Fourier transform, high vacuum scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, the BET multipoint surface area and Moessbauer spectroscopy; as well as, the determination between aqueous media of the isoelectric point and the density of sites of surface of the compound. The octa hydrated ferrous phosphate was obtained pure. The results indicate that the product corresponds to the prospective mineral, the vivianite. The thermal gravimetric analysis demonstrated that the ferrous phosphate is a stable salt after the lost of water. The isoelectric point is since an important parameter because allows to know the behavior of the surface of the material in aqueous systems, in this case the isoelectric point, of the octa hydrated ferrous phosphate, in distilled water is of pH 4.20 and in solution of potassium nitrate 0.5 M is of pH = 3.75. This indicates that the material has an amphoteric surface depending on the pH. On the other hand, the density of active sites of surface obtained by titrations acid-base is of 20 sites by nm 2 . (Author)

Chemical states of p-boronophenylalanine in aqueous carboxylic acids and polyols

International Nuclear Information System (INIS)

Kobayashi, Mitsue; Kitaoka, Yoshinori

1995-01-01

Chemical states of p-boronophenylalanine were studied by infrared (IR) spectroscopy in aqueous carboxylic acids and in aqueous fructose. For BPA in water, the absorption band due to the B-O stretching of trigonal boron was observed, while that of tetrahedral boron was observed for BPA in aqueous oxalic acid. This means BPA forms a complex of tetrahedral boron with oxalate. It was proved that BPA also formed complexes of tetrahedral boron with citric acid as well as with fructose. No appreciable interaction was detected between BPA and maleic acid. (author)

Clean and Efficient Synthesis of Isoxazole Derivatives in Aqueous Media

Directory of Open Access Journals (Sweden)

Daqing Shi

2013-11-01

Full Text Available A series of 5-arylisoxazole derivatives were synthesized via the reaction of 3-(dimethyl-amino-1-arylprop-2-en-1-ones with hydroxylamine hydrochloride in aqueous media without using any catalyst. This method has the advantages of easier work-up, mild reaction conditions, high yields, and an environmentally benign procedure.

A new polymeric adsorbent developing for uranium recovering and richment from aqueous media

International Nuclear Information System (INIS)

Gueler, H.; Aycik, G. A.; Sahiner, N.; Gueven, O.

1997-01-01

Using adsorbents is thought to be the most effective method for recovering the low concentrations of uranium in the aqueous media because of their fast and selective uptake of uranium, a sufficient adsorption capacity and high physical and chemical stability against the media. In this study, a new polymeric adsorbent bearing both hydrophilic groups providing swelling in water and amidoxime groups for chelating with uranyl ions (UO 2 ''2+) has been developed and its adsorptive ability for uranium from aqueous media has been investigated. The polymers obtained by irradiating the solution of polyethylene glycol (PEG) in acrylonitrile (AN) are defined as Interpenetrating Polymer Networks (IPNs) and the adsorbent has been obtained by applying the amidoximation reaction to the IPNs with a conversion of % 60 approximately. Kinetics of the conversion reaction of nitrile (CN) group to amidoxime (HONCNH 2 ) group has been studied by reacting with hydroxylamine (NH 2 OH) solution at a molar ratio of NH 2 OH/CN=1.25 in aqueous media at different temperatures, 30,40,50''0C, for 3-4 days. The degree of amidoximation was determined by UO 2 ''2+ ion adsorption and FTIR spectrometer and the UO 2 ''2+ ion adsorption values were found by both UV and gamma spectrometry and also by gravimetry. It was found that the polymeric adsorbent has a very high adsorption ability for uranium (∼ 540 mg U/g IPN/day)

Extraction from aqueous media novocaine aliphatic alcohols using salting out agent

Directory of Open Access Journals (Sweden)

Y. I. Korenman

2012-01-01

Full Text Available The choice of rational conditions for the extraction of novocaine. Development of effective extraction systems for almost its complete removal from aqueous media. Establishing correlations between coefficients distribution (lgD novocaine and the number of C–atoms in a molecule of alcohol.

Non-aqueous titration of hydroxamic acids.

Science.gov (United States)

Stamey, T W; Christian, R

1966-01-01

Benzohydroxamic acid is titrated with 0.1M tetrabutyl-anunonium hydroxide in nine non-aqueous solvents with three different indicating electrodes. The best results are obtained using dimethylformamide as solvent and platinum-platinum electrodes. Four monoprotic and three diprotic hydroxamie acids and iron(III) benzohydroxamate have been successfully titrated with this system. The effect of quantitative additions of carbon dioxide to the titrant on its apparent molarity are found to be dependent on the amount added, the strength and sample size of acid titrated and the solvent used.

Behaviour of polycrystalline fluoride-selective membrane electrode in aqueous-organic media

International Nuclear Information System (INIS)

Manakova, L.I.; Bausova, N.V.; Moiseev, V.E.; Bamburov, V.G.; Sivoplyas, A.P.

1978-01-01

The behaviour of polycrystalline fluoride membrane electrode (RFME) in aqueous-organic media has been studied when the content of the organic component (methanol, ethanol, acetone, dioxane) has been changed from 20 to 80 mass%. Since LaF 3 is the base of the membrane, its solubility has been studied depending on the organic component content in the solution. It has been established that LaF 3 solubility decreases with increasing content of of the organic component. This explains the effect of the composition of an aqueous-organic solvent on the electrode sensitivity. The electrode sensitivity rises with increasing content of the organic component in an aqueous-organic solvent. A greater decrease of LaF 3 solubility in aqueous-organic solvents as compared with that of LaCl 3 , La(NO 3 ) 3 , and La 2 (SO 4 ) 3 causes a higher selectivity of RFME with respect to the anions under study

Dissolution properties of co-amorphous drug-amino acid formulations in buffer and biorelevant media.

Science.gov (United States)

Heikkinen, A T; DeClerck, L; Löbmann, K; Grohganz, H; Rades, T; Laitinen, R

2015-07-01

Co-amorphous formulations, particularly binary drug-amino acid mixtures, have been shown to provide enhanced dissolution for poorly-soluble drugs and improved physical stability of the amorphous state. However, to date the dissolution properties (mainly intrinsic dissolution rate) of the co-amorphous formulations have been tested only in buffers and their supersaturation ability remain unexplored. Consequently, dissolution studies in simulated intestinal fluids need to be conducted in order to better evaluate the potential of these systems in increasing the oral bioavailability of biopharmaceutics classification system class II drugs. In this study, solubility and dissolution properties of the co-amorphous simvastatin-lysine, gibenclamide-serine, glibenclamide-threonine and glibenclamide-serine-threonine were studied in phosphate buffer pH 7.2 and biorelevant media (fasted and fed state simulated intestinal fluids (FaSSIF and FeSSIF, respectively)). The co-amorphous formulations were found to provide a long-lasting supersaturation and improve the dissolution of the drugs compared to the crystalline and amorphous drugs alone in buffer. Similar improvement, but in lesser extent, was observed in biorelevant media suggesting that a dissolution advantage observed in aqueous buffers may overestimate the advantage in vivo. However, the results show that, in addition to stability advantage shown earlier, co-amorphous drug-amino acid formulations provide dissolution advantage over crystalline drugs in both aqueous and biorelevant conditions.

Products of aqueous vitamin B5 (pantothenic acid) formed by free radical reactions

International Nuclear Information System (INIS)

Schittl, H.; Quint, R.M.; Getoff, N.

2007-01-01

The radiolysis of aqueous vitamin B5 (pantothenic acid) has been investigated under various experimental conditions. The highest vitamin degradation (G=3.22) was observed in solutions saturated with N 2 O, where 90% OH radicals are operating. As final products, the following were established: aldehydes, carboxylic acids and ammonia. Their yield strongly depends on the presence/absence of air as well as on N 2 O (used to convert e aq - into OH) and was determined as a function of absorbed radiation dose. HPLC-analysis showed that in all media, a main product is formed, having the highest yield in aerated solutions. Based on the chemical analysis, it appears that the OH radicals are most involved in the degradation process. A precise sequence of the reaction steps could not be given presently, because of the implication of many simultaneous reactions

Aqueous media treatment and decontamination of hazardous chemical and biological substances by contact plasma

International Nuclear Information System (INIS)

Pivovarov, A.; Kravchenko, A.; Kublanovsky, V.

2009-01-01

Usage of non-equilibrium contact plasma for processes of decontamination and neutralization in conditions of manifestation of chemical, biological and radiation terrorism takes on special significance due to portability of equipment and its mobility in places where toxic liquid media hazardous for people's health are located. Processes of decontamination of aqueous media, seminated with pathogenic microorganisms and viruses, treatment of water containing toxic heavy metals, cyanides, surface-active substances, and heavy radioactive elements, are investigated. Examples of activation processes in infected water and toxic aqueous solutions present convincing evidence of the way, how new quality technological approach for achievement of high enough degree of the said media treatment is used in each specific case. Among new properties of water activated as a result of action of non-equilibrium contact plasma, it is necessary to mention presence of cluster structure, confirmed by well-known spectral and physical-chemical methods, presence of peroxide compounds, active particles and radicals. Anti-microbial activity which is displayed under action of plasma in aqueous media (chemically pure water, drinking water, aqueous solutions of sodium chloride, potassium iodide, as well as other inorganic compounds) towards wide range of pathogenic and conventionally pathogenic microorganisms allows use them as reliable, accessible and low-cost preparations for increasing the degree of safety of food products. Combination of such processes with known methods of filtration and ultra-filtration gives an efficient and available complex capable of withstanding any threats, which may arise for population and living organisms. Present-day level of machine-building, electrical engineering, and electronics allows predict creation of industrial plasma installations, adapted to conditions of various terrorist threats, with minimized power consumption and optimized technological parameters

Aqueous media treatment and decontamination of hazardous chemical and biological substances by contact plasma

Energy Technology Data Exchange (ETDEWEB)

Pivovarov, A; Kravchenko, A [Ukrainian State University of Chemical Engineering, Dnepropetrovsk (Ukraine); Kublanovsky, V [V. I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Science, Kiev (Ukraine)

2009-07-01

Usage of non-equilibrium contact plasma for processes of decontamination and neutralization in conditions of manifestation of chemical, biological and radiation terrorism takes on special significance due to portability of equipment and its mobility in places where toxic liquid media hazardous for people's health are located. Processes of decontamination of aqueous media, seminated with pathogenic microorganisms and viruses, treatment of water containing toxic heavy metals, cyanides, surface-active substances, and heavy radioactive elements, are investigated. Examples of activation processes in infected water and toxic aqueous solutions present convincing evidence of the way, how new quality technological approach for achievement of high enough degree of the said media treatment is used in each specific case. Among new properties of water activated as a result of action of non-equilibrium contact plasma, it is necessary to mention presence of cluster structure, confirmed by well-known spectral and physical-chemical methods, presence of peroxide compounds, active particles and radicals. Anti-microbial activity which is displayed under action of plasma in aqueous media (chemically pure water, drinking water, aqueous solutions of sodium chloride, potassium iodide, as well as other inorganic compounds) towards wide range of pathogenic and conventionally pathogenic microorganisms allows use them as reliable, accessible and low-cost preparations for increasing the degree of safety of food products. Combination of such processes with known methods of filtration and ultra-filtration gives an efficient and available complex capable of withstanding any threats, which may arise for population and living organisms. Present-day level of machine-building, electrical engineering, and electronics allows predict creation of industrial plasma installations, adapted to conditions of various terrorist threats, with minimized power consumption and optimized technological parameters

Pulse radiolysis of pyridinecarboxylic acids in aqueous solution

DEFF Research Database (Denmark)

Solar, S.; Getoff, N.; Sehested, K.

1991-01-01

The reactivity of OH, e(aq)- and H radicals towards aqueous carboxypyridines: picolinic acid (2-pyridinecarboxylic acid), PA; isonicotinic acid (4-pyridinecarboxylic acid), i-NA; 2,6-pyridinedicarboxylic acid, 2,6-PDCA; and 3,5-pyridinedicarboxylic acid, 3,5-PDCA was investigated in the pH-range 1...... radical are: 20% for PA, 75% for i-NA, 60% for 2,6-PDCA and 25% for 3,5-PDCA (a yield of 50% has been found earlier for nicotinic acid, NA)....

Extraction of americium from acid aqueous solutions by diethyl-2-hexyl-pyro-phosphoric acid

International Nuclear Information System (INIS)

Guillaume, Bernard

1971-02-01

After having outlined the interesting properties of americium and the difficulties of its recovery, the author reports the study of the mechanism of extraction of americium from acid aqueous solutions by using the diethyl-2hexyl-pyro-phosphoric acid. Several aspects are thus discussed: influence of concentration of H 2 DEHPP, influence of the acidity of the aqueous phase, saturation of extracting agent, influence of the diluting agent, complexing of americium, influence of other cations. In a second part, the author reports the application to the recovery of americium from effluents, and discusses the obtained results

Spontaneous and Directional Bubble Transport on Porous Copper Wires with Complex Shapes in Aqueous Media.

Science.gov (United States)

Li, Wenjing; Zhang, Jingjing; Xue, Zhongxin; Wang, Jingming; Jiang, Lei

2018-01-24

Manipulation of gas bubble behaviors is crucial for gas bubble-related applications. Generally, the manipulation of gas bubble behaviors generally takes advantage of their buoyancy force. It is very difficult to control the transportation of gas bubbles in a specific direction. Several approaches have been developed to collect and transport bubbles in aqueous media; however, most reliable and effective manipulation of gas bubbles in aqueous media occurs on the interfaces with simple shapes (i.e., cylinder and cone shapes). Reliable strategies for spontaneous and directional transport of gas bubbles on interfaces with complex shapes remain enormously challenging. Herein, a type of 3D gradient porous network was constructed on copper wire interfaces, with rectangle, wave, and helix shapes. The superhydrophobic copper wires were immersed in water, and continuous and stable gas films then formed on the interfaces. With the assistance of the Laplace pressure gradient between two bubbles, gas bubbles (including microscopic gas bubbles) in the aqueous media were subsequently transported, continuously and directionally, on the copper wires with complex shapes. The small gas bubbles always moved to the larger ones.

Products of aqueous vitamin B5 (pantothenic acid) formed by free radical reactions

Energy Technology Data Exchange (ETDEWEB)

Schittl, H. [Section of Radiation Biology, Department of Nutritional Sciences, University of Vienna, Althanstr. 14, UZA II, A-1090 Vienna (Austria); Quint, R.M. [Section of Radiation Biology, Department of Nutritional Sciences, University of Vienna, Althanstr. 14, UZA II, A-1090 Vienna (Austria); Getoff, N. [Section of Radiation Biology, Department of Nutritional Sciences, University of Vienna, Althanstr. 14, UZA II, A-1090 Vienna (Austria)]. E-mail: nikola.getoff@univie.ac.at

2007-10-15

The radiolysis of aqueous vitamin B5 (pantothenic acid) has been investigated under various experimental conditions. The highest vitamin degradation (G=3.22) was observed in solutions saturated with N{sub 2}O, where 90% OH radicals are operating. As final products, the following were established: aldehydes, carboxylic acids and ammonia. Their yield strongly depends on the presence/absence of air as well as on N{sub 2}O (used to convert e{sub aq} {sup -} into OH) and was determined as a function of absorbed radiation dose. HPLC-analysis showed that in all media, a main product is formed, having the highest yield in aerated solutions. Based on the chemical analysis, it appears that the OH radicals are most involved in the degradation process. A precise sequence of the reaction steps could not be given presently, because of the implication of many simultaneous reactions.

Thermochemistry of aqueous pyridine-3-carboxylic acid (nicotinic acid)

Energy Technology Data Exchange (ETDEWEB)

Goncalves, Elsa M. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto Politecnico de Setubal, ESTBarreiro, Rua Americo da Silva Marinho, 2839-001 Lavradio (Portugal); Rego, Talita S. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Minas da Piedade, Manuel E., E-mail: memp@fc.ul.p [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisboa (Portugal)

2011-06-15

Research highlights: {yields} We determined the {Delta}{sub sol}H{sub m} of solid nicotinic acid (NA) in water by solution calorimetry. {yields} We determined {Delta}{sub dil}H{sub m} of an aqueous nicotinic acid solution by flow calorimetry. {yields} We determined (aq, {infinity}) for the 3 NA species involved in acid/base equilibria. {yields} We determined the enthalpy of formation of NA(aq) under saturation conditions.. - Abstract: The molar enthalpy of solution of solid nicotinic acid (NA) at T = 298.15 K, to give an aqueous solution of molality m = 3.748 . 10{sup -3} mol {center_dot} kg{sup -1}, was determined as {Delta}{sub sol}H{sub m} = (19,927 {+-} 48) J {center_dot} mol{sup -1}, by solution calorimetry. Enthalpies of dilution, {Delta}{sub dil}H{sub m}, of 0.1005 mol {center_dot} kg{sup -1} aqueous nicotinic acid to yield final solutions with molality in the approximate range (0.03 to 0.09) mol {center_dot} kg{sup -1} were also measured by flow calorimetry. Combining the two sets of data and the results of pH measurements, with values of proton dissociation enthalpies and {Delta}{sub f}H{sub m}{sup 0}(NA, cr) selected from the literature, it was possible to derive the standard molar enthalpies of formation of the three nicotinic acid species involved in protonation/deprotonation equilibria, at infinite dilution: {Delta}{sub f}H{sub m}{sup 0}(HN{sup +}C{sub 5}H{sub 4}COOH.{infinity}H{sub 2}O,aq) = (328.2 {+-} 1.2) kJ {center_dot} mol{sup -1}, {Delta}{sub f}H{sub m}{sup 0}(HN{sup +}C{sub 5}H{sub 4}COO{sup -}.{infinity}H{sub 2}O,aq) = (325.0 {+-} 1.2) kJ {center_dot} mol{sup -1}, and {Delta}{sub f}H{sub m}{sup 0}(NC{sub 5}H{sub 4}COO{sup -}.{infinity}H{sub 2}O,aq) = (313.7 {+-} 1.2) kJ {center_dot} mol{sup -1}. Finally, the enthalpy of solution of nicotinic acid at T = 298.15 K, under saturation conditions (m = 0.138 mol {center_dot} kg{sup -1}), and the standard molar enthalpy of formation of the corresponding solution could also be obtained as {Delta

Effect of passivation on the sensitivity and stability of pentacene transistor sensors in aqueous media

KAUST Repository

Khan, Hadayat Ullah

2011-06-01

Charge-detecting biosensors have recently become the focal point of biosensor research, especially research onto organic thin-film transistors (OTFTs), which combine compactness, a low cost, and fast and label-free detection to realize simple and stable in vivo diagnostic systems. We fabricated organic pentacene-based bottom-contact thin-film transistors with an ultra-thin insulating layer of a cyclized perfluoro polymer called CYTOP (Asahi Glass Co., Tokyo, Japan) on SiO2 for operation in aqueous media. The stability and sensitivity of these transistor sensors were examined in aqueous buffer media with solutions of variable pH levels after the passivation of perfluoro polymers with thicknesses ranging from 50 to 300nm. These transistor sensors were further modified with an ultra-thin film (5nm) functional layer for selective BSA/antiBSA detection in aqueous buffer media, demonstrating a detection capability as low as 500nM of concentrated antiBSA. The dissociation constant from the antiBSA detection results was 2.1×10-6M. Thus, this study represents a significant step forward in the development of organic electronics for a disposable and versatile chemical and bio-sensing platform. © 2011 Elsevier B.V.

Interaction Studies of Dilute Aqueous Oxalic Acid

Directory of Open Access Journals (Sweden)

Kiran Kandpal

2007-01-01

Full Text Available Molecular conductance λm, relative viscosity and density of oxalicacid at different concentration in dilute aqueous solution were measured at 293 K.The conductance data were used to calculate the value association constant.Viscosity and density data were used to calculate the A and B coefficient ofJone-Dole equation and apparent molar volume respectively. The viscosityresults were utilized for the applicability of Modified Jone-Dole equation andStaurdinger equations. Mono oxalate anion acts, as structure maker and thesolute-solvent interaction were present in the dilute aqueous oxalic acid.

Recovery of homogeneous polyoxometallate catalysts from aqueous and organic media by a mesoporous ceramic membrane without loss of catalytic activity

NARCIS (Netherlands)

Roy Chowdhury, S.; Roy Chowdhury, Sankhanilay; Witte, Peter T.; Blank, David H.A.; Alsters, Paul L.; ten Elshof, Johan E.

2006-01-01

The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous γ-alumina membranes is reported. The recovery of Q12[WZn3(ZnW9O34)2] (Q=[MeN(n-C8H17)3]+) from toluene-based media was quantitative within

Speciation of organotin compounds by capillary electrophoresis: comparison of aqueous and mixed organic-aqueous systems

Energy Technology Data Exchange (ETDEWEB)

Guo, Lei; Matysik, Frank-Michael; Glaeser, Petra [Universitaet Leipzig, Institut fuer Analytische Chemie, Leipzig (Germany)

2004-10-01

A capillary electrophoresis method with direct ultraviolet detection was developed for the analysis of organotin species. Despite the fact that direct detection of organotin compounds by ultraviolet absorption is difficult because most organotins possess poor chromophoric properties, the application of low wavelength ({lambda}=200 nm) and mixed organic-aqueous media enabled a significant enhancement in sensitivity. A mixed organic-aqueous system (10% methanol/40% acetonitrile/50% H{sub 2}O) containing acetic acid and tetrabutylammonium perchlorate formed the basis for rapid, efficient and sensitive determinations of organotin cations such as tripropyltin, tributyltin, triphenyltin and diphenyltin. The concentration limits of detection (LOD) for the four organotin compounds were in the range of 0.4-14 {mu}M, comparable to that obtained with the most sensitive indirect UV method reported until now, and took advantage of a stable baseline, a symmetric peak shape and an absence of disturbing system peaks. The relative standard deviations (n=7) for the relative peak time and peak area were 0.44-0.77 and 4.8-5.8%, respectively. In addition to sensitivity enhancements, the use of organic-aqueous systems instead of pure aqueous media resulted in improved selectivity and efficiency of separations. (orig.)

An improved synthesis of 1,3,5-triaryl-2-pyrazolines in acetic acid aqueous solution under ultrasound irradiation

Directory of Open Access Journals (Sweden)

Lin Zhi-Ping

2007-03-01

Full Text Available Abstract Background Pyrazoline derivatives have been found to possess a broad spectrum of biological activities. Among various pyrazoline derivatives, 2-pyrazolines seem to be the most frequently studied. A variety of methods have been reported for the preparation of this class of compound. However, in spite of their potential utility, some of the reported methods suffer from drawbacks such as long reaction times, cumbersome product isolation procedures and environmental concerns. Organic reactions in aqueous media have attracted increasing interest recently because of environmental issues and the understanding of biochemical processes. Ultrasound has increasingly been used in organic synthesis in the last three decades. A large number of organic reactions can be carried out in higher yields, shorter reaction time or milder conditions under ultrasound irradiation. Results Preparation of a series of 1,3,5-triaryl-2-pyrazolines through the reaction of chalcones and phenylhydrazine hydrochloride was carried out in 83–96% yield within 1.5–2 h in sodium acetate-acetic acid aqueous solution under ultrasound irradiation. Conclusion We have described a practical and convenient procedure for the synthesis of 1,3,5-triaryl-2-pyrazolines in sodium acetate-acetic acid aqueous solution at room temperature under ultrasound irradiation.

Solvent extraction of Zn(II) from aqueous sulphate media by di(2-ethylhexyl) phosphoric acid in kerosene

International Nuclear Information System (INIS)

Begum, D.A.; Alauddin, M.; Rahman, M.S.

2009-01-01

The extraction equilibrium studies of Zn(II) from sulphate medium by di(2-ethylhexyl) phosphoric acid (D2EHPA, H/sub 2/A/sub 2/) in kerosene revealed that the distribution ratio (D) decreased with the increase of initial (Zn(A(II) in the aqueous phase and increased with the increase of equilibrium pH and extractant concentration. The equilibration is reached within 2 min. The species extracted into the organic phase is thought to be ZnA2, HA. The pH and extractant dependencies were about 2 and 1.67, respectively. The distribution ratio decreased with the increase in sulphate ion concentration in the aqueous phase. The extraction equilibrium reaction is suggested as Zn/sup 2+/ /sub aq/ +1.5 (H/sub 2/A/sub 2/)org - (ZnA/sub 2/, HA)org +2H/sup +/ /sub aq/. The extraction equilibrium constant (kex) for the above reaction was calculated to be 10-2.26. The extraction process was endothermic in nature having positive DH value of 16.27 kJ/mol. The loading of D2EHPA by Zn(II) is about 4.50 g of Zn(II) by 0.10 M D2EHPA. Possible reaction mechanism has been suggested based on distribution data, extractant concentration and equilibrium pH of the aqueous phase. (author)

The study of CO2 absorption intensification using porous media material in aqueous AMP solution

Directory of Open Access Journals (Sweden)

Min Xiao

2018-03-01

Full Text Available In this work, the performance of CO2 absorption into aqueous 2-amino-2-methyl-propanol (AMP solution was investigated by measuring the amount of CO2 in the liquid phase during CO2 absorption process to identify initial CO2 absorption rate. Then, the porous media material named as MCM41 was introduced into the amine solution to test its influence on CO2 absorption. It was found that MCM41 increased initial CO2 absorption rate and enhanced CO2 absorption process. The physico-chemical properties of MCM41 were characterized in terms of specific surface area, average pore diameter, total pore volume and chemical properties, the amount of acidic sites and the Brϕnsted/Lewis (B/L acid sites ratio. Results showed that MCM41 was a type of Lewis acid catalyst with large specific surface area and pore volume. In addition, the pKa of AMP solution with and without MCM41 was obtained using acid titration technology to help understand the effect brought by MCM41. A mechanism illustrating how MCM41 increases the CO2 absorption rate of the AMP solution was proposed and demonstrated that MCM41 is a potential material for enhancing CO2 absorption.

Experimental investigation of aqueous corrosion of R7T7 nuclear glass at 90 degrees C in the presence of humic acids: A kinetic approach

International Nuclear Information System (INIS)

Gin, S.; Godon, N.; Mestre, J.P.; Vernaz, E.Y.; Beaufort, D.

1994-01-01

The dissolution kinetics of the French open-quotes R7T7close quotes nonradioactive LWR reference glass in solutions containing dissolved humic acids were investigated at 9O degrees C during static tests with imposed or free pH. Experiments conducted in highly dilute media, with a glass-surface-area-to-solution-volume (SA/V) ratio of 5 m -1 , showed that the glass dissolution surface reaction is catalyzed by humic acids. With higher degrees of reaction progress (SA/V = 100 m -1 and free pH) the humic acids impose pH modifications on the system compared with inorganic media; moreover, they directly or indirectly enhance the dissolution of certain alkali metals and transition elements, forming aqueous complexes with the latter. During experiments with an imposed pH of 8.5 (SA/V = 1300 and 5300 m -1 ), the humic acids appear to cause increased silica solubility that cannot be accounted for by the formation of silica complexes. A residual corrosion rate in the humic acid media exceeding the rate measured in inorganic media suggests that, in addition to silica, one or more element complexes formed by humic acids may be a kinetically limiting factor. This hypothesis must be confirmed, however, as the quantity of humic acids per unit glass surface area was too small in this experiment to allow unambiguous characterization of the phenomenon

A Greener, Efficient Approach to Michael Addition of Barbituric Acid to Nitroalkene in Aqueous Diethylamine Medium

Directory of Open Access Journals (Sweden)

Hany J. Al-Najjar

2014-01-01

Full Text Available An efficient method for the synthesis of a variety of pyrimidine derivatives 3a–t by reaction of barbituric acids 1a,b as Michael donor with nitroalkenes 2a–k as Michael acceptor using an aqueous medium and diethylamine is described. This 1,4-addition strategy offers several advantages, such as using an economic and environmentally benign reaction media, high yields, versatility, and shorter reaction times. The synthesized compounds were identified by 1H-NMR, 13C-NMR, CHN, IR, and MS. The structure of compound 3a was further confirmed by single crystal X-ray structure determination.

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…

Treatment of infectious skin defects or ulcers with electrolyzed strong acid aqueous solution.

Science.gov (United States)

Sekiya, S; Ohmori, K; Harii, K

1997-01-01

A chronic ulcer with an infection such as methicillin-resistant Staphylococcus aureus is hard to heal. Plastic and reconstructive surgeons often encounter such chronic ulcers that are resistant to surgical or various conservative treatments. We applied conservative treatment using an electrolyzed strong acid aqueous solution and obtained satisfactory results. The lesion was washed with the solution or soaked in a bowl of the solution for approximately 20 min twice a day. Fresh electrolyzed strong acid aqueous solution is unstable and should be stored in a cool, dark site in a sealed bottle. It should be used within a week after it has been produced. Here we report on 15 cases of infectious ulcers that were treated by electrolyzed strong acid aqueous solution. Of these cases, 7 patients were healed, 3 were granulated, and in 5, infection subsided. In most cases the lesion became less reddish and less edematous. Discharge or foul odor from the lesion was decreased. Electrolyzed strong acid aqueous solution was especially effective for treating a chronic refractory ulcer combined with diabetes melitus or peripheral circulatory insufficiency. This clinically applied therapy of electrolyzed strong acid aqueous solution was found to be effective so that this new therapeutic technique for ulcer treatment can now be conveniently utilized.

The extraction of rhodium from aqueous nitric acid by dinonylnaphthalene sulphonic acid

International Nuclear Information System (INIS)

Patel, N.M.; Miles, J.H.; Thornback, J.R.

1987-01-01

The extraction of rhodium from aqueous nitric acid using dinonylnaphthalene sulphonic acid has been investigated. The extraction occurs readily from 0.1 M to 1.0 M nitric acid and, since the rhodium is extracted as {Rh(H 2 O) 6 } 3+ into the inverted micelles of the organic solution, equilibration times are less than 5 minutes. Extraction is enhanced by addition of nitrite ion to form {Rh(H 2 O) 5 NO 2 } 2+ as the extracted species. (author)

Sorption of per- and polyfluoroalkyl substances (PFASs) on filter media: implications for phase partitioning studies.

Science.gov (United States)

Chandramouli, Bharat; Benskin, Jonathan P; Hamilton, M Coreen; Cosgrove, John R

2015-01-01

Per- and polyfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are ubiquitous in the environment. Investigations into their fate and potential phase-partitioning behavior require separating solid from aqueous phases via filtration. However, sorption of aqueous-phase PFASs on filtration media may lead to underestimation of PFAS concentrations in the aqueous phase. The authors investigated the sorption of perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids (PFPiAs), polyfluoroalkyl phosphate monoesters, polyfluoroalkyl phosphate diesters (diPAPs), fluorotelomer sulfonates, and perfluorooctane sulfonamide on filtration media. The effects of concentration (3 spiking levels), filter media (4 types), matrix (4 matrices), and compound structure on sorption are reported. Glass fiber filtration resulted in the least sorption, whereas polytetrafluoroethylene filters resulted in the most sorption (up to 98%). Analyte concentration had no significant effect. Sorption was generally consistent across matrix types except for samples affected by aqueous film forming foam deployment, which displayed high sorption of PFOS on nylon filters. Sorption usually increased with an increasing number of carbon or fluorine atoms and was most pronounced for PFPiAs and diPAPs (30–75% sorption). Overall, glass fiber filters are more recommended than nylon filters in environmental samples when phase separation is required. Use of filtration media for PFAS must be preceded by matrix-specific testing to account for unpredictable effects. (C)2014 SETAC

Study of the europium behavior in aqueous media

International Nuclear Information System (INIS)

Fernandez R, E.; Jimenez R, M.; Solache R, M.; Martinez M, V.

1999-01-01

Europium as waste can produce a pollution problem in water that is in contact with it, what would has a heavy environmental impacts, because of the possibilities of diffusion of these wastes from their place of confinement or storage until the geo and biosphere. The solution of such problem requires of a lot of knowledge over the behavior of several chemical elements such as europium in aqueous solutions. In this work it was used a low ion force (0.02 M). The data set will allow extrapolate the hydrolytic behavior of europium in too much minors ion force media, such as the ground waters, including in ion force zero

Hydrometallurgical process for the recovery of metal values from spent lithium-ion batteries in citric acid media.

Science.gov (United States)

Chen, Xiangping; Zhou, Tao

2014-11-01

In this paper, a hydrometallurgical process has been proposed to recover valuable metals from spent lithium-ion batteries in citric acid media. Leaching efficiencies as high as 97%, 95%, 94%, and 99% of Ni, Co, Mn, and Li were achieved under the optimal leaching experimental conditions of citric acid concentration of 2 mol L(-1), leaching temperature of 80 °C, leaching time of 90 min, liquid-solid ratio of 30 ml g(-1), and 2 vol. % H2O2. For the metals recovery process, nickel and cobalt were selectively precipitated by dimethylglyoxime reagent and ammonium oxalate sequentially. Then manganese was extracted by Na-D2EHPA and the manganese-loaded D2EHPA was stripped with sulfuric acid. The manganese was recovered as MnSO4 in aqueous phase and D2EHPA could be reused after saponification. Finally, lithium was precipitated by 0.5 mol L(-1) sodium phosphate. Under their optimal conditions, the recovery percentages of Ni, Co, Mn, and Li can reach 98%, 97%, 98%, and 89%, respectively. This is a relatively simple route in which all metal values could be effectively leached and recovered in citric acid media. © The Author(s) 2014.

Chemical dosimetry by UV spectrophotometry of aqueous ascorbic acid solutions

International Nuclear Information System (INIS)

Alian, A.; El-Assay, N.B.; Abdel-Rehim, F.; Amin, N.E.; McLaughlin, W.L.; Roushdy, H.

1984-01-01

The decrease in the ultraviolet absorption of aqueous solutions of ascorbic acid brought about by large doses of gamma radiation has been investigated as a means of developing a new chemical dosimeter. Because of spontaneous ring opening under various conditions after dissolution in water, some additives were examined as possible stabilizers against such denaturing of aqueous ascorbic acid. At an ascorbic acid concentration of 10 -4 M, either 1 to 2% glycine or 0.2 M NaCl was found to be a good stabilizer. A mechanism of radiation chemistry has been proposed based on hydroxyl radical and hydroxyl adduct intermediates, leading to dehydroascorbic acid through the ascorbate complex. The optimum dosimeter solution covers an absorbed dose range approx. 50 to 350 Gy, when measured at 264 nm wavelength. The G-values for dehydroascorbic acid production were determined to be 2.94 +- 0.33 and 2.43 +- 0.11 (100 eV) -1 , with glycine and NaCl used respectively as stabilizers. (author)

Development of a pH-responsive imprinted polymer for diclofenac and study of its binding properties in organic and aqueous media.

Science.gov (United States)

Mohajeri, Seyed Ahmad; Malaekeh-Nikouei, Bizhan; Sadegh, Hasan

2012-05-01

Three different molecularly imprinted polymers (MIPs) for drug delivery of diclofenac in gastrointestinal tract were synthesized employing bulk polymerization method and their binding and release properties were studied in different pH values. Methacrylic acid (MAA), methacrylamide (MAAM) and 4-vinyl pyridine (4VP) were tested as functional monomers and ethylene glycole dimethacrylate (EDMA) was used as a cross-linker monomer in polymeric feed. Binding properties and imprinting factor (IF) of MIPs were studied in comparison with their non-imprinted ones (Blank) in organic and aqueous media. Diclofenac release in aqueous solvents at pH values of 1.5, 6.0 and 8.0, simulating gastrointestinal fluids, were also studied. The results indicated the specific binding of diclofenac to imprinted polymers. Duo to the stronger non-specific bounds in aqueous solutions, IF values decreased in water compared to acetonitrile as an organic medium. Our results proved that all polymers represented pH-responsive diclofenac delivery at above conditions. The data showed that imprinted polymer, prepared by MAA had superior properties, in comparison with other polymers, for minimum release (14%) of drug in gastric acid and maximum release (90%) in basic condition. The results indicated that diclofenac imprinted polymer could be used as a pH-responsive matrix in preparation of a new drug delivery system for diclofenac.

Extraction Equilibrium of Acrylic Acid by Aqueous Two-Phase Systems Using Hydrophilic Ionic Liquids

International Nuclear Information System (INIS)

Lee, Yong Hwa; Lee, Woo Youn; Kim, Ki-Sub; Hong, Yeon Ki

2014-01-01

As an effective method for extraction of acrylic acid, aqueous two-phase systems based on morpholinium ionic liquids were used in this study. Effects of the alkyl chain length of cation in morpholinium ionic liquids on phase diagram and extraction efficiencies were investigated. Experimental results show that aqueous two phase systems can be formed by adding appropriate amount of morpholinium ionic liquids to aqueous K 2 HPO 4 solutions. It can be found that the ability of morpholinium ionic liquids for phase separation followed the order [HMMor][Br]>[OMMor][Br]>[BMMor][Br]>[EMMor][Br]. There was little difference between binodal curves of imidazolium ionic liquids and those of morpholinium ionic liquids. 50-90% of the extraction efficiency was observed for acrylic acid by aqueous two phase extraction of acrylic acid with morpholinium ionic liquids. It can be concluded that morpholinium ionic liquids/K 2 HPO 4 were effective for aqueous two phases extraction of acrylic acid comparing to imidazolium ionic liquids/K 2 HPO 4 systems because of their lower cost

Nitrous Acid as an Oxidant in Acidic Media

Science.gov (United States)

1979-09-25

current work is the account of Ogsts and Sawski3 who studied the oxidation of benzyl ethers at 90C in acidic, aqueous dioxane. They found an increase in...and G. Tobin, Chem. Com., 180 (1978); (b) J. Hoggett , R. Moodie, and K. Schofield, Chem. Comm., 605 (1969). 15. (a) B. Challis and A. Lawson. J. Chem

Electrochemical studies on the reduction of uranyl ions in nitric acid-hydrazine media at platinum electrode

International Nuclear Information System (INIS)

Mishra, Satyabrata; Sini, K.; Mallika, C.; Kamachi Mudali, U.; Jagadeeswara Rao, Ch.

2015-01-01

Production of uranous nitrate with good conversion efficiency is one of the major steps in the aqueous reprocessing of spent fuels of nuclear reactors, as U(IV) is used for the separation of Pu from U by the selective reduction of Pu(IV) into practically non-extractable Pu(III) in aqueous streams. Electro-reduction of uranyl ions has the advantage of not introducing corrosive chemicals into the process stream. High current efficiency with maximum conversion of U(VI) to U(IV) can be achieved in continuous as well as batch mode electro-reduction, if the process is voltage-controlled rather than current controlled. As potentiostatic studies reveal the mechanism of reduction of uranyl ions in potential controlled electrolysis, the reduction behavior of uranyl ions (UO 2 2+ ) in nitric acid and nitric acid-hydrazine media were investigated by Cyclic Voltammetric (CV) and Chronopotentiometric (CP) techniques using platinum working electrode at 298 K. Heterogeneous electron transfer rate constant (ks) for uranyl reduction was estimated at a very low concentration of nitric acid (0.05 M) using Klinger and Kochi equation. Values of the diffusion coefficients were determined as a function of acidity with and without hydrazine. Reduction of uranyl ions was found to be under kinetic as well as diffusion control when the concentration of nitric acid was 0.05 M and in the absence of hydrazine. However, as the acidity of the supporting electrolyte increased, the reduction was purely under kinetic control. (author)

Smart surfaces with switchable superoleophilicity and superoleophobicity in aqueous media: Toward controllable oil/water separation

KAUST Repository

Zhang, L.; Zhang, Z.; Wang, Peng

2012-01-01

Advanced materials with surfaces that have controllable oil wettability when submerged in aqueous media have great potential for various underwater applications. Here we have developed smart surfaces on commonly used materials, including non

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

Photophysical and photoprototropic characteristics of phenothiazine in aqueous and β-cyclodextrin media

Energy Technology Data Exchange (ETDEWEB)

Rajamohan, Rajaram, E-mail: rajmohanau@gmail.com [Department of Chemistry, S.K.P Institute of Technology, Tiruvannamalai 606611 (India); Nayaki, Sundararajulu Kothai [Chemistry Section, FEAT, Annamalai University, Annamalainagar 608002 (India); Sivakumar, Krishnamoorthy [Department of Chemistry, SCSV University, Enathur, Kanchipuram 631561 (India); Swaminathan, Meenakshisundaram [Department of Chemistry, Annamalai University, Annamalainagar 608002 (India)

2015-12-15

The photophysical and photoprototropic characteristics of phenothiazine (PTZ) in aqueous and β-cyclodextrin (β-CD) media have been investigated using absorption, steady state and time resolved fluorescence measurements. The absorbance and fluorescence intensities of the neutral and monocationic forms of PTZ are enhanced by the addition of β-cyclodextrin and it is due to the formation of 1:1 inclusion complex. The formation of complex is confirmed by the decay analysis and Job's continuous variation method in the liquid state while FT-IR spectral study and SEM image analysis in the solid state. The peak and pK{sub a}* values of PTZ in aqueous media are higher than in β-CD medium, which reveals that the >NH group of PTZ lies in the β-CD cavity. - Highlights: • Increase in the absorbance and fluorescence intensity of PTZ by the addition of β-CDx is confirmed the complex formation. • Biexponential decay is noticed for PTZ by the addition of β-CDx is due to the formation of inclusion complex. • FT-IR and SEM images analysis confirms complex between PTZ and β-CDx in solid state. • The pK{sub a} and pK{sub a}* values of PTZ in aqueous medium is higher than in β-CDx medium, which reveals that the >NH group of PTZ lies in the β-CDx cavity. • The orientation of the inclusion complex is proposed by PatchDock server.

Colorimetric study of oxidation kinetics of thiolactic acid (2 - mercaptopropionic acid) by hexacyanoferrate (III) in acid and alkaline media

International Nuclear Information System (INIS)

Kachhwaha, O.P.; Potter, P.C.; Kapoor, R.C.

1985-01-01

The oxidation kinetics of thiolactic acid by hexacyanoferrate (III) in acid and alkaline media employing the calorimetric method have been described. The two compounds react in equimolar ratio in both media, but the kinetic results are different in both media. In acid medium the total order is three, two with respect to thiol and one in oxidant. The rate of the reaction shows an inverse proportionality to (H + ) and also varies inversely with decreasing dielectric constant of the medium. In alkaline medium, the total order of the reaction is two, being unity in each reactant. The rate increases with increased pH value. Additions of ferrocyanide and dithio dilactic acid have no effect on the rate in both media. Additions of a neutral electrolyte does not affect the rate in the acid medium, while a positive salt effect was observed in an alkaline medium. Activation parameters have been evaluated in both media and in a medium of low dialectric. Different reaction schemes have been proposed for acid and alkaline media and have satisfactory explained the experimental data, except for the pH rate. (author)

Uranium (VI) transport in saturated heterogeneous media: Influence of kaolinite and humic acid.

Science.gov (United States)

Chen, Chong; Zhao, Kang; Shang, Jianying; Liu, Chongxuan; Wang, Jin; Yan, Zhifeng; Liu, Kesi; Wu, Wenliang

2018-05-07

Natural aquifers typically exhibit a variety of structural heterogeneities. However, the effect of mineral colloids and natural organic matter on the transport behavior of uranium (U) in saturated heterogeneous media are not totally understood. In this study, heterogeneous column experiments were conducted, and the constructed columns contained a fast-flow domain (FFD) and a slow-flow domain (SFD). The effect of kaolinite, humic acid (HA), and kaolinite/HA mixture on U(VI) retention and release in saturated heterogeneous media was examined. Media heterogeneity significantly influenced U fate and transport behavior in saturated subsurface environment. The presence of kaolinite, HA, and kaolinite/HA enhanced the mobility of U in heterogeneous media, and the mobility of U was the highest in the presence of kaolinite/HA and the lowest in the presence of kaolinite. In the presence of kaolinite, there was no difference in the amount of U released from the FFD and SFD. However, in the presence of HA and kaolinite/HA, a higher amount of U was released from the FFD. The findings in this study showed that medium structure and mineral colloids, as well as natural organic matter in the aqueous phase had significant effects on U transport and fate in subsurface environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

NIR spectroscopic properties of aqueous acids solutions.

Science.gov (United States)

Omar, Ahmad Fairuz; Atan, Hanafi; Matjafri, Mohd Zubir

2012-06-15

Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R² above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918-925 nm and 990-996 nm, while at 975 nm for water.

Electrochemical behavior of uranyl in anhydrous polar organic media

Energy Technology Data Exchange (ETDEWEB)

Burn, Adam G.; Nash, Kenneth L. [Washington State Univ., Pullmann, WA (United States). Dept. of Chemistry

2017-09-01

Weak complexes between pentavalent and hexavalent actinyl cations have been reported to exist in acidic, non-complexing high ionic strength aqueous media. Such ''cation-cation complexes'' were first identified in the context of actinide-actinide redox reactions in acidic aqueous media relevant to solvent extraction-based separation systems, hence their characterization is of potential interest for advanced nuclear fuel reprocessing. This chemistry could be relevant to efforts to develop advanced actinide separations based on the upper oxidation states of americium, which are of current interest. In the present study, the chemical behavior of pentavalent uranyl was examined in non-aqueous, aprotic polar organic solvents (propylene carbonate and acetonitrile) to determine whether UO{sub 2}{sup +} cations generated at the reducing working electrode surface would interact with the UO{sub 2}{sup 2+} cations in the bulk phase to form cation-cation complexes in such media. In magnesium perchlorate media, the electrolyte adsorbed onto the working electrode surface and interfered with the uranyl reduction/diffusion process through an ECE (electron transfer/chemical reaction/electron transfer) mechanism. In parallel studies of uranyl redox behavior in tetrabutylammonium hexafluorophosphate solutions, an EC (electron transfer/chemical reaction) mechanism was observed in the cyclic voltammograms. Ultimately, no conclusive electrochemical evidence demonstrated uranyl cation-cation interactions in the non-aqueous, aprotic polar organic solvent solutions, though the results reported do not completely rule out the presence of UO{sub 2}{sup +}.UO{sub 2}{sup 2+} complexes.

5-Hydroxymethylfurfural (5-HMF Production from Hexoses: Limits of Heterogeneous Catalysis in Hydrothermal Conditions and Potential of Concentrated Aqueous Organic Acids as Reactive Solvent System

Directory of Open Access Journals (Sweden)

Nadine Essayem

2012-09-01

Full Text Available 5-Hydroxymethylfurfural (5-HMF is an important bio-sourced intermediate, formed from carbohydrates such as glucose or fructose. The treatment at 150–250 °C of glucose or fructose in pure water and batch conditions, with catalytic amounts of most of the usual acid-basic solid catalysts, gave limited yields in 5-HMF, due mainly to the fast formation of soluble oligomers. Niobic acid, which possesses both Lewis and Brønsted acid sites, gave the highest 5-HMF yield, 28%, when high catalyst/glucose ratio is used. By contrast, we disclose in this work that the reaction of fructose in concentrated aqueous solutions of carboxylic acids, formic, acetic or lactic acids, used as reactive solvent media, leads to the selective dehydration of fructose in 5-HMF with yields up to 64% after 2 hours at 150 °C. This shows the potential of such solvent systems for the clean and easy production of 5-HMF from carbohydrates. The influence of adding solid catalysts to the carboxylic acid media was also reported, starting from glucose.

LASERS, ACTIVE MEDIA: The aqueous-polyelectrolyte dye solution as an active laser medium

Science.gov (United States)

Akimov, A. I.; Saletskii, A. M.

2000-11-01

The spectral, luminescent, and lasing properties of aqueous solutions of a cationic dye rhodamine 6G with additions of anion polyelectrolytes — polyacrylic and polymethacrylic acids — are studied. It is found that the energy and spectral properties of lasing of these solutions depend on the ratio of concentrations of polyelectrolyte and molecules. It is also found that the lasing parameters of aqueous-polyelectrolyte dye solutions can be controlled by changing the structure of the molecular system. The variation in the structure of aqueous-polyelectrolyte dye solutions of rhodamine 6G resulted in an almost five-fold increase in the lasing efficiency compared to that in aqueous dye solutions.

Kinetics and mechanism of OsOsub(4) catalyzed oxidation of chalcones by Cesub(4) in aqueous acetic sulfuric acid media

International Nuclear Information System (INIS)

Srinivasulu, P.V.; Adinarayana, M.; Sethuram, B.; Rao, T.N.

1985-01-01

Kinetics of OsOsub(4) catalyzed oxidation of chalcones by Cesup(4+) was studied in aqueous acetic-sulfuric acid medium in the temperature range 313 to 338 K. The order in oxidant is zero while the order with respect to substrate and catalyst are each fractional. The rate of the reaction decreased with increase in percentage of acetic acid while [Hsup(+)] had practically no effect on the rate. The rates of various substituted chalcones are given. A mechanism in which formation of a cyclic ester between chalcone and OsOsub(4) in a fast step followed by its decomposition in a rate-determining step is envisaged. (author)

Enhanced Ga2O3-photocatalyzed and photochemical degradation of the Fipronil insecticide by UVC irradiation in mixed aqueous/organic media under an inert atmosphere.

Science.gov (United States)

Hidaka, Hisao; Tsukamoto, Tohru; Mitsutsuka, Yoshihiro; Oyama, Toshiyuki; Serpone, Nick

2015-05-01

Agrochemicals such as the insecticide Fipronil that bear fluoro groups are generally fat-soluble and nearly insoluble in water, so that their photodegradation in a heterogeneous aqueous gallium oxide dispersion presents some challenges. This article examined the photodegradation of this insecticide by solubilizing it through the addition of organic solvents (EtOH, MeOH, THF, 1,4-dioxane and ethylene glycol) to an aqueous medium and then subjecting the insecticide to 254 nm UVC radiation under photocatalytically inert (Ga2O3/N2) and air-equilibrated (Ga2O3/O2) conditions, as well as photochemically in the absence of Ga2O3 but also under inert and air-equilibrated conditions. Defluorination, dechlorination, desulfonation and denitridation of Fipronil were examined in mixed aqueous/organic media (10, 25 and 50 vol% in organic solvent). After 3 h of UVC irradiation (50 vol% mixed media) defluorination with Ga2O3/N2 was ∼65% greater than in aqueous media, and ca. 80% greater than the direct photolysis of Fipronil under inert (N2) conditions; under air-equilibrated conditions both Ga2O3-photocatalyzed and photochemical defluorination were significantly lower than in aqueous media. Dechlorination of Fipronil was ∼160% (Ga2O3/N2) and 140% (photochemically, N2) greater than in aqueous media; under air-equilibrated conditions, both photocatalyzed and photochemical formation of Cl(-) ions in mixed media fell rather short relative to aqueous media. The photocatalyzed (Ga2O3/N2) and photochemical (N2) conversion of the sulfur group in Fipronil to SO4(2(-)) ions was ca. 20% and 30% greater, respectively, in mixed media, while under air-equilibrated conditions photocatalyzed desulfonation was nearly twofold less than in the aqueous phase; direct photolysis showed little variations in mixed media. Denitridation of the nitrogens in Fipronil occurred mostly through the formation of ammonia (as NH4(+)) under all conditions with negligible quantities of NO3(-); again mixed media

Photolysis of Periodate and Periodic Acid in Aqueous Solution

DEFF Research Database (Denmark)

Sehested, Knud; Kläning, U. K.

1978-01-01

The photochemistry of periodate and periodic acid in aqueous solution was studied (i) by quantum yield measurements at low light intensity (ii) by flash photolysis, and (iii) by photolysis of glassy samples at 77 K. The photochemical studies were supplemented with pulse radiolysis studies...... of aqueous periodate solutions and with kinetic studies using stopped-flow technique. In strongly alkaline solution the photodecomposition of periodate proceeds via formation of O– and IVI. At pH solution O3 P is formed in a small...

TiO2-based photocatalytic disinfection of microbes in aqueous media: A review.

Science.gov (United States)

Laxma Reddy, P Venkata; Kavitha, Beluri; Kumar Reddy, Police Anil; Kim, Ki-Hyun

2017-04-01

The TiO 2 based photocatalyst has great potential for the disinfection/inactivation of harmful pathogens (such as E.coli in aqueous media) along with its well-known usefulness on various chemical pollutants. The disinfection property of TiO 2 is primarily attributed to surface generation of reactive oxygen species (ROS) as well as free metal ions formation. Furthermore, its disinfection capacity and overall performance can be significantly improved through modifications of the TiO 2 material. In this review, we provide a brief survey on the effect of various TiO 2 materials in the disinfection of a wide range of environmentally harmful microbial pathogens (e.g., bacteria, fungi, algae, and viruses) in aqueous media. The influencing factors (such as reactor design, water chemistry, and TiO 2 modifications) of such processes are discussed along with the mechanisms of such disinfection. It is believed that the combined application of disinfection and decontamination will greatly enhance the utilization of TiO 2 photocatalyst as a potential alternative to conventional methods of water purification. Copyright © 2017 Elsevier Inc. All rights reserved.

Curcumin based optical sensing of fluoride in organo-aqueous media using irradiation technique

Science.gov (United States)

Venkataraj, Roopa; Radhakrishnan, P.; Kailasnath, M.

2017-06-01

The present work describes the degradation of natural dye Curcumin in organic-aqueous media upon irradiation by a multi-wavelength source of light like mercury lamp. The presence of anions in the solution leads to degradation of Curcumin and this degradation is especially enhanced in the case of fluoride ion. The degradation of Curcumin is investigated by studying the change in its absorption and fluorescence characteristics in organoaqueous solution upon irradiation. A broad detection range of fluoride ranging from 2.3×10-6-2.22×10-3 M points to the potential of the method of visible light irradiation enabling aqueous based sensing of fluoride using Curcumin.

The depletion of aqueous nitrous acid in packed towers

International Nuclear Information System (INIS)

Counce, R.M.; Crawford, D.B.

1987-01-01

The depletion of aqueous nitrous acid was studied at 298 0 K and at slightly greater than atmospheric pressure. Solutions containing nitrous and nitric acids were contacted with nitrogen in towers packed with 6- and 13-mm Intalox saddles. The results indicate the existence of two depletion mechanisms for the conditions studied - liquid-phase decomposition and direct desorption of nitrous acid. Models based on mass-transfer and chemical-kinetic information are presented to explain the experimental results. 24 refs., 8 figs., 3 tabs

Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part I. Regeneration of Amine-Carboxylic Acid Extracts

Energy Technology Data Exchange (ETDEWEB)

Poole, Loree Joanne [Univ. of California, Berkeley, CA (United States); King, C. Judson [Univ. of California, Berkeley, CA (United States)

1990-03-01

Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO₂ and H₂S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, succinic acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility of lactic acid and the tendency of the acid to self-associate. The separate recovery of ammonia and acid gases from sour waters can be achieved by combining steam-stripping of the acid gases with simultaneous removal of ammonia by extraction with a liquid cation exchanger. The use of di-2,4,4-trimethylpentyl phosphinic acid as the liquid cation exchanger is explored in this work. Batch extraction experiments were carried out to measure the equilibrium distribution ratio of ammonia between an aqueous buffer solution and an organic solution of the phosphinic acid (0.2N) in Norpar 12. The

Polystyrene-Core, Silica-Shell Scintillant Nanoparticles for Low-Energy Radionuclide Quantification in Aqueous Media.

Science.gov (United States)

Janczak, Colleen M; Calderon, Isen A C; Mokhtari, Zeinab; Aspinwall, Craig A

2018-02-07

β-particle emitting radionuclides are useful molecular labels due to their abundance in biomolecules. Detection of β-emission from 3 H, 35 S, and 33 P, important biological isotopes, is challenging due to the low energies (E max ≤ 300 keV) and short penetration depths (≤0.6 mm) in aqueous media. The activity of biologically relevant β-emitters is usually measured in liquid scintillation cocktail (LSC), a mixture of energy-absorbing organic solvents, surfactants, and scintillant fluorophores, which places significant limitations on the ability to acquire time-resolved measurements directly in aqueous biological systems. As an alternative to LSC, we developed polystyrene-core, silica-shell nanoparticle scintillators (referred to as nanoSCINT) for quantification of low-energy β-particle emitting radionuclides directly in aqueous solutions. The polystyrene acts as an absorber for energy from emitted β-particles and can be loaded with a range of hydrophobic scintillant fluorophores, leading to photon emission at visible wavelengths. The silica shell serves as a hydrophilic shield for the polystyrene core, enabling dispersion in aqueous media and providing better compatibility with water-soluble analytes. While polymer and inorganic scintillating microparticles are commercially available, their large size and/or high density complicates effective dispersion throughout the sample volume. In this work, nanoSCINT nanoparticles were prepared and characterized. nanoSCINT responds to 3 H, 35 S, and 33 P directly in aqueous solutions, does not exhibit a change in scintillation response between pH 3.0 and 9.5 or with 100 mM NaCl, and can be recovered and reused for activity measurements in bulk aqueous samples, demonstrating the potential for reduced production of LSC waste and reduced total waste volume during radionuclide quantification. The limits of detection for 1 mg/mL nanoSCINT are 130 nCi/mL for 3 H, 8 nCi/mL for 35 S, and <1 nCi/mL for 33 P.

Synthesis of Co–Al layered double hydroxide nanoclusters as reduction nanocatalyst in aqueous media

Directory of Open Access Journals (Sweden)

Daisuke Kino

2017-12-01

Full Text Available Layered double hydroxides (LDHs have attracted attention as green materials due to their catalytic ability in benign aqueous solvents. We here demonstrate the synthesis of colloidal Co–Al LDH nanoclusters with an average size of <10 nm via a facile liquid-phase reaction for the enhancement of the catalytic activity. To the best of our knowledge, the present LDH is the smallest Co–Al LDH with an extremely large surface area and stability in an aqueous solvent, forming a stable and concentrated colloidal solution as high as 40 g/L. We investigated the formation mechanism, and the catalytic activity of Co–Al LDH nanoclusters. The Co–Al LDH nanoclusters showed 47 times higher rate of the reduction of dye molecules in the aqueous media than standard Co–Al LDH particles with a micrometer size. LDH nanoclusters demonstrated here are promising green nanocatalysts for the aqueous reaction processes.

DETERMINATION OF KINETICS OF DEGRADATION AND MOBILITY OF DITHIOCARBAMATES FUNGICIDES IN AQUEOUS MEDIA AND IN MOROCCAN SOIL

Directory of Open Access Journals (Sweden)

Said El Antri

2010-07-01

Full Text Available Contribution analysis of dithiocarbamates pesticides used on tomatoes treatment has been reported. The study is focused on analysis and determination of some dithiocarbamates like, Maneb, Mancozeb, Zineb and Propineb, in order to achieve accurate impact of theses pesticides on water and soil. Analysis method is based on decomposition of dithiocarbamate by heating under acidic attack to give carbon disulfide complexed with copper acetate solution in presence of diethanolamine. Complex formed is dosed spectrophotometrically at 435 nm. Degradation kinetic of dithiocarbamate in aqueous media have been realized and proved that dithiocarbamate are degraded by simple air exposition. In the other hand, pH affects also dithiocarbamate degradation by increasing hydroxyl ions to participate for dithiocarbamate instability. Dithiocarbamate mobility on Moroccan soils samples have been realised and don’t have the same degradation mode.

Cation exchange properties of zeolites in hyper alkaline aqueous media.

Science.gov (United States)

Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

2015-02-03

Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

Lignin transformations and reactivity upon ozonation in aqueous media

Science.gov (United States)

Khudoshin, A. G.; Mitrofanova, A. N.; Lunin, V. V.

2012-03-01

The reaction of ozone with lignin in aqueous acidic solutions is investigated. The Danckwerst model is used to describe the kinetics of gas/liquid processes occurring in a bubble reactor. The efficient ozonation rate of a soluble lignin analog, sodium lignosulfate, is determined. The main lines of the reaction between ozone and lignin are revealed on the basis of kinetic analysis results and IR and UV spectroscopy data.

Extraction of molybdenum by the di-n-butyl 2.2.N.hydroxyhexanamide (tri-n-butylacetohydroxamic acid) from aqueous acidic media

International Nuclear Information System (INIS)

Landesman, C.

1991-11-01

The design of a new industrial process for the production of the fission product 99 Mo, led to study of the extraction of 99 Mo(VI) by the tri-n-butylacetohydroxamic acid (TBAH). Due to the large affinity of TBAH for Mo(VI), the study was conducted with unusual experimental conditions : the concentrations of the extracting molecule and metallic ion were very low, typically CTBAH = 10 -5 M and CMo(VI) = 10 -8 M. The overall extraction system was described using a mathematical model quite simple, which, in particular, takes into account all the Mo(VI) species present in the aqueous phase. When the extractions were carried out from a perchloric acid medium, two different extraction mechanisms of Mo(VI) were identified : for C HC10 4 3 , the extraction of Mo(VI) corresponds to a cationic exchange, whereas for C HC10 4 > 3 mol/dm 3 , a neutral Mo(VI) compound is extracted. Moreover it was found that the extracting system Mo(VI)/TBAH is extremely sensitive to the temperature. It is thus possible to change the way of the transfer of Mo(VI) between the two phases, by control of the temperature of the mixture : the extraction is carried out at room temperature and the back-extraction at elevated temperature

Poly (ethylene oxide)-block-poly (n-butyl acrylate)-blockpoly (acrylic acid) triblock terpolymers with highly asymmetric hydrophilic blocks: synthesis and aqueous solution properties

OpenAIRE

Petrov, P. (Petar); Yoncheva, K. (Krassimira); Mokreva, P. (Pavlina); Konstantinov, S. (Spiro); Irache, J.M. (Juan Manuel); Müller, A.H.E. (Axel H.E.)

2013-01-01

The synthesis and aggregation behaviour in aqueous media of novel amphiphilic poly(ethylene oxide)- block-poly(n-butyl acrylate)-block-poly(acrylic acid) (PEO–PnBA–PAA) triblock terpolymers were studied. Terpolymers composed of two highly asymmetric hydrophilic PEO (113 monomer units) and PAA (10–17 units) blocks, and a longer soft hydrophobic PnBA block (163 or 223 units) were synthesized by atom transfer radical polymerisation (ATRP) of n-butyl acrylate and tert-butyl acrylate ...

Removal of Ni (II), Co (II) and Pb (II) ions from aqueous media using ...

African Journals Online (AJOL)

Removal of Ni (II), Co (II) and Pb (II) ions from aqueous media using Starch ... The results showed that 0.025 % loaded SSMNPs gave the optimal sorption ... constants (Lagergren and Pseudo-2nd-order) for Ni2+ and Co2+ adsorption were ... Langmuir correlation coefficients showed a better fit for the adsorption isotherms.

Ultrasonic Assisted Synthesis of Chromenes Catalyzed by Sodium Carbonate in Aqueous Media.

Science.gov (United States)

Sabbaghan, Maryam; Sofalgar, Pegah

2015-01-01

A simple, efficient, and environmentally benign procedure for the synthesis of 2-amino-4H-chromene ring has been achieved by the three-component reaction of an aromatic aldehyde, malononitrile and diverse enolizable C-H activated compound under ultrasound irradiation using sodium carbonate as a catalyst in aqueous media. Sodium carbonate as a natural salt, being available as an inexpensive catalyst combined with ultrasound method promoted this protocol in comparison to other methods and catalysts.

Towards water compatible MIPs for sensing in aqueous media.

Science.gov (United States)

Horemans, F; Weustenraed, A; Spivak, D; Cleij, T J

2012-06-01

When synthesizing molecularly imprinted polymers (MIPs), a few fundamental principles should be kept in mind. There is a strong correlation between porogen polarity, MIP microenvironment polarity and the imprinting effect itself. The combination of these parameters eventually determines the overall binding behavior of a MIP in a given solvent. In addition, it is shown that MIP binding is strongly influenced by the polarity of the rebinding solvent. Because the use of MIPs in biomedical environments is of considerable interest, it is important that these MIPs perform well in aqueous media. In this article, various approaches are explored towards a water compatible MIP for the target molecule l-nicotine. To this end, the imprinting effect together with the MIP matrix polarity is fine-tuned during MIP synthesis. The binding behavior of the resulting MIPs is evaluated by performing batch rebinding experiments that makes it possible to select the most suitable MIP/non-imprinted polymer couple for future application in aqueous environments. One method to achieve improved compatibility with water is referred to as porogen tuning, in which porogens of varying polarities are used. It is demonstrated that, especially when multiple porogens are mixed, this approach can lead to superior performance in aqueous environments. Another method involves the incorporation of polar or non-polar comonomers in the MIP matrix. It is shown that by carefully selecting these monomers, it is also possible to obtain MIPs, which can selectively bind their target in water. Copyright © 2012 John Wiley & Sons, Ltd.

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)

Comparative analysis of the effect of pretreating aspen wood with aqueous and aqueous-organic solutions of sulfuric and nitric acid on its reactivity during enzymatic hydrolysis

DEFF Research Database (Denmark)

Dotsenko, Gleb; Osipov, D. O.; Zorov, I. N.

2016-01-01

The effect of aspen wood pretreatment methods with the use of both aqueous solutions of sulfuric and nitric acids and aqueous-organic solutions (ethanol, butanol) of sulfuric acid (organosolv) on the limiting degree of conversion of this type of raw material into simple sugars during enzymatic...

Comparative radiosensitivity of amino acids during γ-radiolysis in aqueous solutions

International Nuclear Information System (INIS)

Duzhenkova, N.A.; Savich, A.V.

1977-01-01

The radiosensitivity of amino acids contained in proteins has been compared. The γ-radiolysis of aqueous solutions of amino acids has studied over a wide range of concentrations in the presence of air, the dose rate being 60 rad/sec, and the dose, 100 krad. Radiation-chemical yields of amino acid decay and ammonia accumulation are given. An increase in yields with amino acid concentration has been established. Assumptions concerning some peculiarities of the amino acid decay mechanism are made

Selective detection of Cu2 + and Co2 + in aqueous media: Asymmetric chemosensors, crystal structure and spectroscopic studies

Science.gov (United States)

Dogaheh, Samira Gholizadeh; Khanmohammadi, Hamid; Carolina Sañudo, E.

2017-05-01

Two new azo-azomethine receptors, H2L1 and H2L2, containing hydrazine, naphthalene and different electron withdrawing groups, Cl and NO2, have been designed and synthesized for qualitative and quantitative detection of Cu2 + and Co2 + in aqueous media. The crystal structure of H2L1is reported. The H2L1was used as a chemosensor for selective detection of trace amount of Cu2 + in aqueous media. H2L2 was also applied to naked-eye distinction of Cu2 + and Co2 + from other transition metal ions in aqueous media. Detection limit of Cu2 + is 1.13 μM and 1.26 μM, in water, for H2L1 and H2L2, respectively, which are lower than the World Health Organization (WHO) recommended level. The binuclear Cu2 + and Co2 + complexes of the receptors have been also prepared and characterized using spectroscopic methods and MALDI-TOF mass analysis. Furthermore, the binding stoichiometry between the receptors upon the addition Cu2 + and Co2 + has been investigated using Job's plot. Moreover, the fluorescence emission spectra of the receptors and their metal complexes are also reported.

Plutonium scrap waste processing based on aqueous nitrate and chloride media

International Nuclear Information System (INIS)

Navratil, J.D.

1985-01-01

A brief review of plutonium scrap aqueous waste processing technology at Rocky Flats is given. Nitric acid unit operations include dissolution and leaching, anion exchange purification and precipitation. Chloride waste processing consists of cation exchange and carbonate precipitation. Ferrite and carrier precipitation waste treatment processes are also described. 3 figs

Electrochemical behavior of meso-substituted iron porphyrins in alkaline aqueous media

Science.gov (United States)

Berezina, N. M.; Bazanov, M. I.; Maksimova, A. A.; Semeikin, A. S.

2017-12-01

The effect meso-substitution in iron porphyrin complexes has on their redox behavior in alkaline aqueous solutions is studied via cyclic voltammetry. The voltammetric features of the reduction of iron pyridylporphyrins suggest that the sites of electron transfer lie at the ligand, the metal ion, and the pyridyl moieties. The electron transfer reactions between the different forms of these compounds, including the oxygen reduction reaction they mediate, are outlined to show the sequence and potential ranges in which they occur in alkaline aqueous media. Under our experimental conditions, the iron porphyrins exist as μ-oxo dimmers whose activity for the electrocatalytic reduction of oxygen displays a considerable dependence on the nature of the substitutents and nitrogen isomerization (for pyridylporphyrins) and grows in the order (Fe( ms-Ph)4P)2O, (Fe[ ms-(Py-3)Ph3]P)2O, (Fe[ ms-(Py-4)4]P)2O, and (Fe[ ms-(Py-3)4]P)2O.

Studies on the solvent extraction behaviour of Pu(IV) from nitric acid, nitric-perchloric acid and hydrochloric acids, by di,2-ethylhexyl phosphoric acid (HDEHP)

International Nuclear Information System (INIS)

Phal, D.G.; Kannan, S.K.; Ramakrishna, V.V.

1994-01-01

Extraction of plutonium (IV) from aqueous nitric acid, nitric-perchloric acid and hydrochloric acids by di,2-ethylhexyl phosphoric acid, the dimeric form of which is represented as H 2 Y 2 , in different diluents (dodecane, toluene and chloroform) was investigated. The composition of the extracted Pu(IV) species were found to be Pu(NO 3 ) 2 (HY) 2 , Pu(NO 3 )(ClO 4 )(HY 2 ) 2 , PuClY(HY 2 ) 2 and PuCl 2 (HY 2 ) 2 from nitric, nitric-perchloric and hydrochloric acids respectively, the last one being pre-dominant at high aqueous acidities (i.e. 5M HCl). Synergic enhancement in the extraction of Pu(IV) from different aqueous media, by the addition of thenoyltrifluoroacetone (HTTA) to HDEHP was also investigated and was attributed to the formation and extraction of the species PuX(TTA)(HY 2 ) 2 , and Pu(TTA) 2 (HY 2 ) 2 where X=Cl - or NO 3 - . The addition of the neutral extractant TOPO to H 2 Y 2 also resulted in synergism. The possible equilibria in these systems were inferred and the corresponding equilibrium constants determined. (author). 24 refs., 10 figs., 10 tabs

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.

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.

Parallel proton transfer pathways in aqueous acid-base reactions

NARCIS (Netherlands)

Cox, M.J.; Bakker, H.J.

2008-01-01

We study the mechanism of proton transfer (PT) between the photoacid 8-hydroxy-1,3, 6-pyrenetrisulfonic acid (HPTS) and the base chloroacetate in aqueous solution. We investigate both proton and deuteron transfer reactions in solutions with base concentrations ranging from 0.25M to 4M. Using

Investigation of the mechanisms of using metal complexation and cellulose nanofiber/sodium alginate layer-by-layer coating for retaining anthocyanin pigments in thermally processed blueberries in aqueous media.

Science.gov (United States)

Jung, Jooyeoun; Cavender, George; Simonsen, John; Zhao, Yanyun

2015-03-25

This study investigated the mechanisms of anthocyanin pigment retention using Fe(3+)-anthocyanin complexation and cellulose nanofiber (CNF)/sodium alginate (SA) layer-by-layer (LBL) coatings on thermally processed blueberries in aqueous media. Anthocyanin pigments were polymerized through complexation with Fe(3+) but readily degraded by heat (93 °C for 7 min) in the aqueous media because of poor stability. CNF/SA LBL coating was successful to retain anthocyanin pigments in thermally processed blueberries. Fruits coated with CNF containing CaCl2 followed by treatment in a SA bath formed a second hydrogel layer onto the CNF layer (LBL coating system) through cross-linking between Ca(2+) and alginic acid. Methyl-cellulose-modified CNF improved the interactions between CNF, the fruit surface, and the SA layer. This study demonstrated that the CNF/SA LBL coating system was effective to retain anthocyanin pigments on thermally processed whole blueberries, whereas no combined benefit of complexation with coating was observed. Results explained the mechanisms of the new approaches for developing colorful and nutritionally enhanced anthocyanin-rich fruit products.

Mechanism of laser ablation for aqueous media irradiated under confined-stress conditions

International Nuclear Information System (INIS)

Oraevsky, A.A.; Jacques, S.L.; Tittel, F.K.

1995-01-01

Pulsed laser ablation of aqueous medium irradiated under conditions of temporal confinement of thermal stress is described. Time-resolved measurements of laser-induced transient stress waves with simultaneous imaging of ablation process by laser-flash photography were performed. Stress transients induced in aqueous solution of K 2 CrO 4 by ablative nanosecond laser pulses at 355 nm were studied by a broad-band lithium niobate acoustic transducer. Recoil momentum upon material ejection was measured from the temporal profiles of the acoustic transducer signal as a function of incident laser fluence. Cavitation bubbles produced in the irradiated volume during the tensile phase of thermoelastic stress were shown to drive material ejection at temperatures substantially below 100 degree C. Experimental data are evident that nanosecond-pulse laser ablation of aqueous media (when temporal stress-confinement conditions are satisfied) include the following two main stages of material ejection: (1) ejection of water microdroplets due to expansion and rupture of subsurface cavitation bubbles; (2) ejection of liquid streams with substantial volume upon collapse of initial crater and large cavitation bubbles in the depth of irradiated volume (after coalescence of smaller bubbles). copyright 1995 American Institute of Physics

Uranyl fluoride luminescence in acidic aqueous solutions

International Nuclear Information System (INIS)

Beitz, J.V.; Williams, C.W.

1996-01-01

Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO 4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO 2 F 2 . Studies on the effect of added LiNO 3 or Na 2 WO 4 ·2H 2 O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF 6 content of WF 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF 6

Primary and secondary kinetic isotope effects in the acid-catalyzed dehydration of 1,1'-diadamantylmethylcarbinol in aqueous acetic acid

International Nuclear Information System (INIS)

Lomas, J.S.

1981-01-01

The sulfuric acid catalyzed dehydration of 1,1'-diadamantyl-methylcarbinol in anhydrous acetic acid proceeds exclusively to 1,1'-bis(1-adamantyl)ethylene. The secondary deuterium isotope effect of 1.32 found for this reaction shows that carbonium ion formation from the protonated alcohol is rate determining. In the presence of water, however, capture of the carbonium ion competes with deprotonation, introducing a primary isotope effect. Consequently, the overall KIE rises, reaching 3.18 for 80% aqueous acetic acid. Analysis of the KIE for 80 to 100% aqueous acetic acid is consistent with a simple classical mechanism involving reversible formation of the intermediate carbonium ion. The primary isotope effect upon deprotonation is at the most 2.98, indicative of an asymmetric transition state close to the carbonium ion

Chromium(VI) sorption efficiency of acid-activated banana peel over organo-montmorillonite in aqueous solutions.

Science.gov (United States)

Ashraf, Anam; Bibi, Irshad; Niazi, Nabeel Khan; Ok, Yong Sik; Murtaza, Ghulam; Shahid, Muhammad; Kunhikrishnan, Anitha; Li, Dongwei; Mahmood, Tariq

2017-07-03

In the present study, we examined sorption of chromate (Cr(VI)) to acid-activated banana peel (AABP) and organo-montmorillonite (O-mont) as a function of pH, initial Cr(VI) concentration at a sorbent dose of 4 g L -1 and at 20 ± 1°C in aqueous solutions. In sorption edge experiments, maximum Cr(VI) removal was obtained at pH 3 after 2 hours by AABP and O-mont (88% and 69%). Sorption isotherm data showed that the sorption capacity of AABP was higher than O-mont (15.1 vs. 6.67 mg g -1 , respectively, at pH 4). Freundlich and Langmuir models provided the best fits to describe Cr(VI) sorption onto AABP (R 2 = 0.97) and O-mont (R 2 = 0.96). Fourier transform infrared spectroscopy elucidated that for AABP mainly the -OH, -COOH, -NH 2 , and for O-mont intercalated amines and -OH surface functional groups were involved in Cr(VI) sorption. The scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX) analyses, although partly, indicate that the (wt. %) proportion of cations (e.g., Ca, Mg) in AABP decreased after Cr(VI) sorption. This may be due to ion exchange of chromite (Cr(III)) (produced from Cr(VI) reduction) with cationic elements in AABP. Also, Cr(VI) desorption (using phosphate solution) from AABP was lower (29%) than that from O-mont (51%) up to the third regeneration cycle. This bench scale comparative study highlights that the utilization of widely available and low-cost acid-activated biomaterials has a greater potential than organo-clays for Cr(VI) removal in aqueous media. However, future studies are warranted to precisely delineate different mechanisms of Cr(VI) sorption/reduction by acid-activated biomaterials and organo-clays.

ELECTROCHEMICAL BEHAVIOUR OF METHYLENE BLUE IN NON-AQUEOUS SOLVENTS

International Nuclear Information System (INIS)

Caram, J.A.; Suárez, J.F. Martínez; Gennaro, A.M.; Mirífico, M.V.

2015-01-01

Graphical abstract: Display Omitted - Highlights: • The dye is electro-reduced in two separated monoelectronic charge transfers. • Solvent/supporting electrolyte/acid/base modifies the electrochemical parameters. • A dissociation equilibrium of the dye in non-aqueous solvent is proposed. • The electro-generated and stable dye-radical is also chemically produced in EDA or KOH/DMF. • A new species is reversibly formed in KOH/EtOH or ACN. - Abstract: The electrochemical behaviour of methylene blue in solution of non-aqueous solvents with different supporting electrolytes was studied by cyclic voltammetry. Dye electro-reduction presents two well-defined processes of monoelectronic charge transfer yielding a free radical in the first process and an anion in the second electron transfer. Free radical and anion are long living species in some of the studied media. Effects of supporting electrolyte and solvent on the peak potentials, the peak current functions and the reversibility of the charge transfer processes are reported. A dissociation equilibrium of the dye in solution of non-aqueous solvents and the acid or base added determine markedly the electrochemical responses. In the particular cases of KOH/DMF or EDA basic media the chemical formation of the stable methylene blue radical was detected and it was characterized by EPR spectroscopy. A general reaction scheme is proposed

Aqueous citric acid as a promising cleaning agent of whey evaporators

DEFF Research Database (Denmark)

Hedegaard, Martina Vavrusova; P. Johansen, Nikolaj; Garcia, André Castilho

2017-01-01

concentration of citric acid was the most effective for all the investigated volumes. From the citric acid solutions, spontaneously supersaturated in calcium citrate tetrahydrate during scale dissolution in the smaller volumes for all citric acid concentrations, calcium citrate tetrahydrate slowly precipitated...... in acceptable purity for technical use. Dissolution efficiency of aqueous solutions of 0.200 mol L−1 nitric acid combined with 0.100, 0.500, and 1.00 mol L−1 citric acid with final volumes of 100, 50, and 25 mL showed synergistic effect especially for the higher concentrations and lower volumes of two acids...

Effects of organic acids, amino acids and ethanol on the radio-degradation of patulin in an aqueous model system

International Nuclear Information System (INIS)

Yun, Hyejeong; Lim, Sangyong; Jo, Cheorun; Chung, Jinwoo; Kim, Soohyun; Kwon, Joong-Ho; Kim, Dongho

2008-01-01

The effects of organic acids, amino acids, and ethanol on the radio-degradation of patulin by gamma irradiation in an aqueous model system were investigated. The patulin, dissolved in distilled water at a concentration of 50 ppm, was practically degraded by the gamma irradiation at the dose of 1.0 kGy, while 33% of the patulin remained in apple juice. In the aqueous model system, the radio-degradation of patulin was partially inhibited by the addition of organic acids, amino acids, and ethanol. The proportions of remaining patulin after irradiation with the dose of 1.0 kGy in the 1% solution of malic acid, citric acid, lactic acid, acetic acid, ascorbic acid, and ethanol were 31.4%, 2.3%, 31.2%, 6.1%, 50.8%, and 12.5%, respectively. During 30 days of storage, the remaining patulin was reduced gradually in the solution of ascorbic acid and malic acid compared to being stable in other samples. The amino acids, serine, threonine, and histidine, inhibited the radio-degradation of patulin. In conclusion, it was suggested that 1 kGy of gamma irradiation (recommended radiation doses for radicidation and/or quarantine in fruits) is effective for the reduction of patulin, but the nutritional elements should be considered because the radio-degradation effects are environment dependent

Benchmarking uranyl peroxide capsule chemistry in organic media

Energy Technology Data Exchange (ETDEWEB)

Neal, Harrison A.; Nyman, May [Department of Chemistry, Oregon State University, Corvallis, OR (United States); Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN (United States)

2017-01-03

Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Benchmarking uranyl peroxide capsule chemistry in organic media

International Nuclear Information System (INIS)

Neal, Harrison A.; Nyman, May; Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C.

2017-01-01

Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The effect of aqueous media on the mechanical properties of fluorapatite-mullite glass-ceramics.

Science.gov (United States)

Mollazadeh, S; Ajalli, Siamak; Kashi, Tahereh S Jafarzadeh; Yekta, Bijan Eftekhai; Javadpour, Jafar; Jafari, S; Youssefi, Abbas; Fazel, Akbar

2015-11-01

To verify the effects of alternating thermal changes in aqueous media and chemical composition on mechanical properties of apatite-mullite glass-ceramics and to investigate concentration of ions eluted from glass-ceramics in aqueous media. The glass compositions were from SiO2Al2O3P2O5CaOTiO2BaOZrO2CaF2 system. Glass-ceramics were prepared by heat-treating at 1100°C for 3h samples alternately immersed in water at 5 and 60°C. The 3-point bending strength (n=10) were determined using 3×4×25mm/bar and a universal testing machine, at a cross-head speed of 0.1mm/min. Vickers micro hardness were evaluated by applying a total of 15-20 indentations under a 100g load for 30s. Concentrations of ions eluted from glass-ceramics immersed in 60±5°C double distilled water were determined by ion chromatography. The toxicity of glass-ceramics was assessed by seeding the osteosarcoma cells (MG63) on powder for different days and their cell proliferation assessment was investigated by MTT assay. The data were analyzed using one way analysis of variance and the means were compared by Tukey's test (5% significance level). The highest flexural strength and hardness values after thermal changes belonged to TiO2 and ZrO2 containing glass-ceramics which contained lower amount of released ions. BaO containing glass-ceramic and sample with extra amount of silica showed the highest amount of reduction in their mechanical strength values. These additives enhanced the concentration of eluted ions in aqueous media. MTT results showed that glass-ceramics were almost equivalent concerning their in-vitro biological behavior. Thermal changes and chemical compositions had significant effects on flexural strength and Vickers micro-hardness values. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

PREPARATION AND CHARACTERIZATION OF IRON THIN FILM ELECTRODEPOSED ON A VITREOUS CARBON ELECTRODE IN AQUEOUS AND ORGANIC MEDIA: A COMPARATIVE STUDY

Directory of Open Access Journals (Sweden)

A LOUNAS

2010-06-01

studied on a vitreous carbon electrode in various aqueous and organic media. The deposit of iron was studied by cyclic voltammetry; the quantity of iron deposited was determined by integration of the cathodic and anodic peaks of Fe (0 and Fe (II of the various media.

A reaction-based fluorescent sensor for detection of cyanide in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Wang, Shan-Teng; Sie, Yi-Wun [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China); Wan, Chin-Feng [School of Applied Chemistry, Chung Shan Medical University, Taichung City 40201, Taiwan (China); Wu, An-Tai, E-mail: antai@cc.ncue.edu.tw [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China)

2016-05-15

A simple boronic acid derivative was utilized as a reaction-based receptor for CN{sup −} in aqueous solution. The receptor showed a selective and sensitive response to CN{sup −} over other various anions via nucleophilic addition of CN{sup −} to the imine moiety of the boronic-based receptor.

A contribution to the study of thorium and neptunium (IV) complexes in acidic phosphoric media; Contribution a l`etude des complexes de thorium et de neptunium (IV) en milieux phosphoriques acides

Energy Technology Data Exchange (ETDEWEB)

Ghafar, M

1995-11-30

The thorium and neptunium (IV) phosphate complexes formation in acidic media has been investigated, essentially at the indicator`s level with {sup 227} Th, {sup 234} Th, {sup 235} Np and {sup 239} Np. Solvent extraction, a commonly used method for determining stability constants in solutions, was used with HDEHP in toluene. In order to get a better understanding of inorganic transparent gels formation in phosphoric aqueous solutions, the effect of the thorium concentration is also studied. Specific experimental conditions have been chosen in order to avoid the formation of chelate and hydrolysis in the aqueous solution. The equilibrium constants and stability constants are calculated, and the results are compared with literature. The results show that increasing the thorium concentration does not lead to polymer forms. refs., 42 figs., 19 tabs.

Removal of Aqueous Boron by Using Complexation of Boric Acid with Polyols: A Raman Spectroscopic Study

Energy Technology Data Exchange (ETDEWEB)

Eom, Ki Heon; Jeong, Hui Cheol; An, Hye Young; Lim, Jun-Heok; Lee, Jea-Keun; Won, Yong Sun [Pukyong National University, Busan (Korea, Republic of)

2015-12-15

Boron is difficult to be removed from seawater by simple RO (reverse osmosis) membrane process, because the size of boric acid (B(OH){sub 3}), the major form of aqueous boron, is as small as the nominal pore size of RO membrane. Thus, the complexation of boric acid with polyols was suggested as an alternative way to increase the size of aqueous boron compounds and the complexation behavior was investigated with Raman spectroscopy. As a reference, the Raman peak for symmetric B-O stretching vibrational mode both in boric acid and borate ion (B(OH){sub 4}{sup -}) was selected. A Raman peak shift (877 cm{sup -1} →730 cm{sup -1}) was observed to confirm that boric acid in water is converted to borate ion as the pH increases, which is also correctly predicted by frequency calculation. Meanwhile, the Raman peak of borate ion (730 cm{sup -1}) did not appear as the pH increased when polyols were applied into aqueous solution of boric acid, suggesting that the boric acid forms complexing compounds by combining with polyols.

Pulse Radiolysis of Adrenaline in Acid Aqueous Solutions

DEFF Research Database (Denmark)

Gohn, M.; Getoff, N.; Bjergbakke, Erling

1976-01-01

Pulse radiolysis of adrenaline in acid aqueous solutions (pH 1–3) was carried out. The rate constants for the reactions of adrenaline with H and OH were determined: k(H + adr.) = (0·9±0·1) × 109 dm3 mol−1s−1; k(OH + adr.) = (1·65±0·15) × 1010 dm3 mol−1s−1. The H-adduct of adrenaline has two λmax...

Study of thermodynamic and acoustic behaviour of nicotinic acid in binary aqueous mixtures of D-lactose

Science.gov (United States)

Sharma, Ravi; Thakur, R. C.

2017-07-01

In the present study, the thermodynamic properties such as partial molar volumes, partial molar expansibilities, partial molar compressibilities, partial molar heat capacities and isobaric thermal expansion coefficient of different solutions of nicotinic acid in binary aqueous mixtures of D-lactose have been determined at different temperatures (298.15, 303.15, 308.15, 313.15) K. Masson's equation is used to interpret the data in terms of solute-solute and solute-solvent interactions. In the present study it has been found that nicotinic acid behaves as structure maker in aqueous and binary aqueous mixtures of D-lactose.

Inhibitive action of some plant extracts on the corrosion of steel in acidic media

Energy Technology Data Exchange (ETDEWEB)

Abdel-Gaber, A.M. [Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt)]. E-mail: ashrafmoustafa@yahoo.com; Abd-El-Nabey, B.A. [Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt); Sidahmed, I.M. [Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt); El-Zayady, A.M. [Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt); Saadawy, M. [Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt)

2006-09-15

The effect of extracts of Chamomile (Chamaemelum mixtum L.), Halfabar (Cymbopogon proximus), Black cumin (Nigella sativa L.), and Kidney bean (Phaseolus vulgaris L.) plants on the corrosion of steel in aqueous 1 M sulphuric acid were investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. EIS measurements showed that the dissolution process of steel occurs under activation control. Potentiodynamic polarization curves indicated that the plant extracts behave as mixed-type inhibitors. The corrosion rates of steel and the inhibition efficiencies of the extracts were calculated. The results obtained show that the extract solution of the plant could serve as an effective inhibitor for the corrosion of steel in sulphuric acid media. Inhibition was found to increase with increasing concentration of the plant extract up to a critical concentration. The inhibitive actions of plant extracts are discussed on the basis of adsorption of stable complex at the steel surface. Theoretical fitting of different isotherms, Langmuir, Flory-Huggins, and the kinetic-thermodynamic model, were tested to clarify the nature of adsorption.

Removal of fluoride from aqueous nitric acid

International Nuclear Information System (INIS)

Pruett, D.J.; Howerton, W.B.; Mailen, J.C.

1981-06-01

Several methods for removing fluoride from aqueous nitric acid were investigated and compared with the frequently used aluminum nitrate-calcium nitrate (Ca 2+ -Al 3+ ) chemical trap-distillation system. Zirconium oxynitrate solutions were found to be superior in preventing volatilization of fluoride during distillation of the nitric acid, producing decontamination factors (DFs) on the order of 2 x 10 3 (vs approx. 500 for the Ca 2+ -Al 3+ system). Several other metal nitrate systems were tested, but they were less effective. Alumina and zirconia columns proved highly effective in removing HF from HF-HNO 3 vapors distilled through the columns; fluoride DFs on the order of 10 6 and 10 4 , respectively, were obtained. A silica gel column was very effective in adsorbing HF from HF-HNO 3 solutions, producing a fluoride DF of approx. 10 4

Removal of nitrate, ammonia and phosphate from aqueous solutions in packed bed filter using biochar augmented sand media

Directory of Open Access Journals (Sweden)

El Hanandeh Ali

2017-01-01

Full Text Available Nutrients from wastewater are a major source of pollution because they can cause significant impact on the ecosystem. Accordingly, it is important that the nutrient concentrations are kept to admissible levels to the receiving environment. Often regulatory limits are set on the maximum allowable concentrations in the effluent. Therefore, wastewater must be treated to meet safe levels of discharge. In this study, laboratory investigation of the efficiency of packed bed filters to remove nitrate, ammonium and phosphate from aqueous solutions were conducted. Sand and sand augmented with hydrochloric acid treated biochar (SBC were used as packing media. Synthetic wastewater solution was prepared with PO43−, NO3−, NH4+ concentrations 20, 10, 50 mg/L, respectively. Each experiment ran for a period of five days; samples from the effluent were collected on alternate days. All experiments were duplicated. Over the experiment period, the average removal efficiency of PO43−, NO3−, NH4+ were 99.2%, 72.9%, 96.7% in the sand packed columns and 99.2%, 82.3%, 97.4% in the SBC packed columns, respectively. Although, the presence of biochar in the packing media had little effect on phosphate and ammonium removal, it significantly improved nitrate removal.

Gamma-irradiation of malic acid in aqueous solutions. [prebiotic significance

Science.gov (United States)

Negron-Mendoza, A.; Graff, R. L.; Ponnamperuma, C.

1980-01-01

The gamma-irradiation of malic acid in aqueous solutions was studied under initially oxygenated and oxygen-free conditions in an attempt to determine the possible interconversion of malic acid into other carboxylic acids, specifically those associated with Krebs cycle. The effect of dose on product formation of the system was investigated. Gas-liquid chromatography combined with mass spectrometry was used as the principal means of identification of the nonvolatile products. Thin layer chromatography and direct probe mass spectroscopy were also employed. The findings show that a variety of carboxylic acids are formed, with malonic and succinic acids in greatest abundance. These products have all been identified as being formed in the gamma-irradiation of acetic acid, suggesting a common intermediary. Since these molecules fit into a metabolic cycle, it is strongly suggestive that prebiotic pathways provided the basis for biological systems.

Kinetics of Oxidation of Some Amino Acids by N-Chlorosaccharin in Aqueous Acetic Acid Medium

Directory of Open Access Journals (Sweden)

N. A. Mohamed Farook

2004-01-01

Full Text Available The kinetics of oxidation of some amino acids namely, glycine, alanine, aspartic acid, arginine, and histidine, (AA by N-chlorosaccharin (NCSA in aqueous acetic acid medium in the presence of perchloric acid have been investigated. The observed rate of oxidation is first order in [AA], [NCSA] and of inverse fractional order in [H+]. The main product of the oxidation is the corresponding aldehyde. The ionic strength on the reaction rate has no significant effect. The effect of changing the dielectric constant of the medium on the rate indicates the reaction to be of dipole-dipole type. Hypochlorous acid has been postulated as the reactive oxidizing species. The reaction constants involved in the mechanism are derived. The activation parameters are computed with respect to slow step of the mechanism.

Volatility of Organic Aerosol: Evaporation of Ammonium Sulfate/Succinic Acid Aqueous Solution Droplets

Science.gov (United States)

2013-01-01

Condensation and evaporation modify the properties and effects of atmospheric aerosol particles. We studied the evaporation of aqueous succinic acid and succinic acid/ammonium sulfate droplets to obtain insights on the effect of ammonium sulfate on the gas/particle partitioning of atmospheric organic acids. Droplet evaporation in a laminar flow tube was measured in a Tandem Differential Mobility Analyzer setup. A wide range of droplet compositions was investigated, and for some of the experiments the composition was tracked using an Aerosol Mass Spectrometer. The measured evaporation was compared to model predictions where the ammonium sulfate was assumed not to directly affect succinic acid evaporation. The model captured the evaporation rates for droplets with large organic content but overestimated the droplet size change when the molar concentration of succinic acid was similar to or lower than that of ammonium sulfate, suggesting that ammonium sulfate enhances the partitioning of dicarboxylic acids to aqueous particles more than currently expected from simple mixture thermodynamics. If extrapolated to the real atmosphere, these results imply enhanced partitioning of secondary organic compounds to particulate phase in environments dominated by inorganic aerosol. PMID:24107221

Thermophysical property characterization of aqueous amino acid salt solution containing serine

International Nuclear Information System (INIS)

Navarro, Shanille S.; Leron, Rhoda B.; Soriano, Allan N.; Li, Meng-Hui

2014-01-01

Highlights: • Thermophysical properties of aqueous potassium and sodium salt solutions of serine were studied. • Density, viscosity, refractive index and electrolytic conductivity of the solution were measured. • The concentrations of amino acid salt ranges from x 1 = 0.009 to 0.07. • The temperature range studied was (298.15 to 343.15) K. • The measured data were represented satisfactorily by using the applied correlations. - Abstract: Thermophysical property characterization of aqueous potassium and sodium salt solutions containing serine was conducted in this study; specifically the system’s density, refractive index, electrical conductivity, and viscosity. Measurements were obtained over a temperature range of (298.15 to 343.15) K and at normal atmospheric pressure. Composition range from x 1 = 0.009 to 0.07 for aqueous potassium and sodium salt solutions containing serine was used. The sensitivity of the system’s thermophysical properties on temperature and composition variation were discussed and correlated based on the equations proposed for room temperature ionic liquids. The density, viscosity, and refractive index measurements of the aqueous systems were found to decrease as the temperature increases at fixed concentration and the values increase as the salt concentration increases (water composition decreases) at fixed temperature. Whereas, a different trend was observed for the electrical conductivity data; at fixed concentration, the conductivity values increase as the temperature increases and at fixed temperature, its value generally increases as the salt concentration increases but only to a certain level (specific concentration) wherein the conductivity of the solution starts to decrease when the concentration of the salt is further increased. Calculation results show that the applied models were satisfactory in representing the measured properties in the aqueous amino acid salt solution containing serine

Enthalpic characteristics of interactions occurring between an ascorbic acid and some saccharides in aqueous solutions

International Nuclear Information System (INIS)

Terekhova, Irina V.; Kulikov, Oleg V.; Titova, Elena S.

2004-01-01

The enthalpies of solution of mono- and disaccharides were measured in water and aqueous ascorbic acid solutions at 298.15 K using a calorimeter of solution. Enthalpies of transfer of saccharides from water to aqueous ascorbic acid solutions were derived, and enthalpic coefficients of pair interaction h xy were calculated according to MacMillan-Mayer theory. Interactions of ascorbic acid with D-fructose and sucrose are energetically favorable and characterized by negative h xy coefficients while h xy for the interactions occurring between ascorbic acid and α-D glucose, D-galactose and maltose are positive. The obtained results are interpreted in terms of the influence of structure and solvation of solutes on the thermodynamic parameters of their interaction in solutions

Physicochemical characterization of in situ drug-polymer nanocomplex formed between zwitterionic drug and ionomeric material in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Salamanca, Constain H., E-mail: chsalamanca@icesi.edu.co [Pharmaceutical physical chemistry laboratory, Department of Pharmacy, Faculty of Natural Sciences, ICESI University, Cali (Colombia); Castillo, Duvan F.; Villada, Juan D. [Pharmaceutical physical chemistry laboratory, Department of Pharmacy, Faculty of Natural Sciences, ICESI University, Cali (Colombia); Rivera, Gustavo R. [SIT Biotech GmbH, BMZ 2 Otto-Hahn-Str. 15, 44227 Dortmund (Germany)

2017-03-01

Biocompatible polymeric materials with the potential to form functional structures, in association with different therapeutic molecules, in physiological media, represent a great potential for biological and pharmaceutical applications. Therefore, here the formation of a nano-complex between a synthetic cationic polymer and model drug (ampicillin trihydrate) was studied. The formed complex was characterized by size and zeta potential measurements, using dynamic light scattering and capillary electrophoresis. Moreover, the chemical and thermodynamically stability of these complexes were studied. The ionomeric material, here referred as EuCl, was obtained by equimolar reaction between Eudragit E and HCl. The structural characterization was carried out by potentiometric titration, FTIR spectroscopy, and DSC. The effect of pH, time, polymer concentration and ampicillin/polymer molar ratio over the hydrodynamic diameter and zeta potential were established. The results show that EuCl ionomer in aqueous media presents two different populations of nanoparticles; one of this tends to form flocculated aggregates in high pH and concentrations, by acquiring different conformations in solution by changing from a compact to an extended conformation. Moreover, the formation of an in situ interfacial polymer-drug complex was demonstrated, this could slightly reduce the hydrolytic degradation of the drug while affecting its solubility, mainly under acidic conditions. - Highlights: • The EuCl ionomer in aqueous media presents two different populations of nanoparticle, corresponding to proximally 15 nm and 150 nm. • The EuCl ionomer in aqueous media may form different structure depending on the pH and polymer concentration, which tends to form flocculated aggregates in high pH and concentrations. • The formation of an in situ interfacial polymer-drug complex was demonstrated, which could slightly reduce the hydrolytic degradation of the drug and affecting its solubility in

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.

Measuring and modeling aqueous electrolyte/amino-acid solutions with ePC-SAFT

International Nuclear Information System (INIS)

Held, Christoph; Reschke, Thomas; Müller, Rainer; Kunz, Werner; Sadowski, Gabriele

2014-01-01

Highlights: • Amino-acid solubilities and osmotic coefficients in ternary solutions containing one amino acids and one salt measured. • Weak salt influence on amino-acid solubilities except for salts containing Mg [2+] or NO 3 [−] (salting-in behavior). • Osmotic coefficients dominated by the solute with the highest molality. • Amino-acid solubilities and osmotic coefficients predicted reasonably with ePC-SAFT with deviations of 3.7% and 9.3%. • Predictions based on pure-component parameters for ions and amino acids using no ion/amino-acid fitting parameters. -- Abstract: In this work thermodynamic properties of electrolyte/amino acid/water solutions were measured and modeled. Osmotic coefficients at 298.15 K were measured by means of vapor-pressure osmometry. Amino-acid solubility at 298.15 K was determined gravimetrically. Considered aqueous systems contained one of the four amino acids: glycine, L-/DL-alanine, L-/DL-valine, and L-proline up to the respective amino-acid solubility limit and one of 13 salts composed of the ions Li + , Na + , K + , NH 4 + , Cl − , Br − , I − , NO 3 − , and SO 4 2− at salt molalities of 0.5, 1.0, and 3.0 mol · kg −1 , respectively. The data show that the salt influence is more pronounced on osmotic coefficients than on amino-acid solubility. The electrolyte Perturbed-Chain Statistical Association Theory (ePC-SAFT) was applied to model thermodynamic properties in aqueous electrolyte/amino-acid solutions. In previous works, this model had been applied to binary salt/water and binary amino acid/water systems. Without fitting any additional parameters, osmotic coefficients and amino-acid solubility in the ternary electrolyte/amino acid/water systems could be predicted with overall deviations of 3.7% and 9.3%, respectively, compared to the experimental data

The extraction of trace amounts of gold from different aqueous mineral acid solutions by diphenyl-2-pyridylmethane dissolved in chloroform

International Nuclear Information System (INIS)

Iqbal, M.; Ejaz, M.; Chaudhri, S.A.; Zamiruddin

1978-01-01

Diphenyl-2-pyridylmethane, a high-molecular-weight substituted pyridine has been examined. Its behaviour is similar to that of amines in that it forms salts with mineral acids. The acid ionization constant (pKsub(BHsup(+)) is 4.4+-0.06 at 25 deg C. A study of the partition behaviour of trace amounts of gold between mineral acid solutions and 0.1 M diphenyl-2-pyridylmethane dissolved in chloroform indicates that the metal can be quantitatively extracted from dilute mineral acid solutions and also from concentrated hydrochloric acid media in a single extraction. Common anions have little effect on extraction in concentrations up to 1 M. Separation factors of a number of metal ions relative to gold are reported for three mineral acid systems. Gold has been estimated in some synthetic samples using a neutron-activation technique by prior extraction with 0.1 M solution of diphenyl-2-pyridylmethane dissolved in chloroform. Distribution of the test elements between aqueous and organic phase was followed radiometrically. The solutions (usually 1 cm 3 ) were shaken in stoppered vials for 5 minutes using a mechanical shaker. After separation of the layers, 500 μl of each phase were taken for radiochemical analysis. The standard deviation did not exceed 1%. (T.G.)

Precipitation stripping of neodymium from carboxylate extractant with aqueous oxalic acid solutions

International Nuclear Information System (INIS)

Konishi, Yasuhiro; Asai, Satoru; Murai, Tetuya

1993-01-01

This paper describes a precipitation stripping method in which neodymium ions are stripped from carboxylate extractant in organic solvent and simultaneously precipitated with aqueous oxalic acid solution. For the single-stage process, a quantitative criterion for precipitating oxalate powders was derived theoretically, and stripping experiments were done under the precipitation conditions. The resultant precipitates were neodymium oxalate, which is completely free from contamination by the carboxylate extractant and the organic solvent. The overall rate of stripping was controlled by the transfer of neodymium carboxylate in the organic solution, indicating that the presence of oxalic acid in the aqueous phase has no effect on the stripping rate. These findings demonstrate the feasibility of combining the conventional stripping and precipitation stages in a solvent extraction process for separation and purification of rare earths

The use of biosorbents for heavy metals removal from aqueous media

International Nuclear Information System (INIS)

Al-Masri, M. S.; Amin, Y.

2010-04-01

Biomaterials, which could be adsorbed heavy metals, such bacteria, algae, yeasts, fungi and agricultural waste, is called Biomass. Recently, they are widely used for heavy metal removal from aqueous media, due to their large available quantities, low cost and good performance. The biosorbent, unlike mono functional ion exchange resins, contains variety of functional sites including carboxyl, imidazole, sulphydryl, amino, phosphate, sulfate, thioether, phenol, carbonyl, amide and hydroxyl moieties. In this paper, the biosorbents word widely and nationally used for heavy metal removal were reviewed. Their biosorption performance, their pretreatment and modification, aiming to improve their sorption capacity, and regeneration/reuse was introduced and evaluated. The potential application of biosorption and biosorbents was discussed. (author)

Direct Capture of Organic Acids From Fermentation Media Using Ionic Liquids

Energy Technology Data Exchange (ETDEWEB)

Klasson, K.T.

2004-11-03

Several ionic liquids have been investigated for the extraction of organic acids from fermentation broth. Partitioning of representative organic acids (lactic, acetic, and succinic) between aqueous solution and nine hydrophobic ionic liquids was measured. The extraction efficiencies were strongly dependent on pH of the aqueous phase. Distribution coefficient was very good (approximately 60) at low succinic acid concentrations for one of the ionic liquids (trihexyltetradecylphosphonium methanesulfonate) at neutral pH. However, this ionic liquid had to be diluted with nonanol due to its high viscosity in order to be useful. A diluent (trioctylamine) was also added to this mixture. The results suggest that an extraction system based on ionic liquids may be feasible for succinic acid recovery from fermentation broth and that two ideal extraction stages are needed to reduce the concentration from 33 g/L to 1 g/L of succinic acid. Further studies are needed to evaluate other issues related to practical applications, including ionic liquid loss in the process, toxicity effects of ionic liquids during simultaneous fermentation and extractions.

Selective hydrolysis of phosphate monoester by a supramolecular phosphatase formed by the self-assembly of a bis(Zn(2+)-cyclen) complex, cyanuric acid, and copper in an aqueous solution (cyclen = 1,4,7,10-tetraazacyclododecane).

Science.gov (United States)

Zulkefeli, Mohd; Suzuki, Asami; Shiro, Motoo; Hisamatsu, Yosuke; Kimura, Eiichi; Aoki, Shin

2011-10-17

In Nature, organized nanoscale structures such as proteins and enzymes are formed in aqueous media via intermolecular interactions between multicomponents. Supramolecular and self-assembling strategies provide versatile methods for the construction of artificial chemical architectures for controlling reaction rates and the specificities of chemical reactions, but most are designed in hydrophobic environments. The preparation of artificial catalysts that have potential in aqueous media mimicking natural enzymes such as hydrolases remains a great challenge in the fields of supramolecular chemistry. Herein, we describe that a dimeric Zn(2+) complex having a 2,2'-bipyridyl linker, cyanuric acid, and a Cu(2+) ion automatically assembles in an aqueous solution to form a 4:4:4 complex, which is stabilized by metal-ligand coordination bonds, π-π-stacking interactions, and hydrogen bonding and contains μ-Cu(2)(OH)(2) cores analogous to the catalytic centers of phosphatase, a dinuclear metalloenzyme. The 4:4:4 complex selectively accelerates the hydrolysis of a phosphate monoester, mono(4-nitrophenyl)phosphate, at neutral pH.

Experimental and Theoretical Studies of the Acid-Catalyzed Conversion of Furfuryl Alcohol to Levulinic Acid in Aqueous Solution

Energy Technology Data Exchange (ETDEWEB)

Gonzalez Maldonado, Gretchen M.; Assary, Rajeev S.; Dumesic, James A.; Curtiss, Larry A.

2012-02-14

The conversion of furfuryl alcohol (FAL) to levulinic acid over Amberlyst TM 15 in aqueous media was investigated using a combination of liquid chromatography-mass spectrometry (LC-MS) measurements, isotopic labeling studies, nuclear magnetic resonance (NMR) spectroscopy, and ab initio quantum chemical calculations using the G4MP2 method. The results of these combined studies showed that one of the major reaction pathways takes place via a geminal diol species (4,5,5- trihydroxypentan-2-one, denoted as intermediate A), formed by the addition of two water molecules to FAL, where two of the oxygen atoms from FAL are retained. This geminal diol species can also be produced from another intermediate found to be a dimer-like species, denoted as intermediate B. This dimer-like species is formed at the early stages of reaction, and it can also be converted to intermediate A, indicating that intermediate B is the product of the reaction of FAL with another early intermediate. Quantum chemical calculations suggested this to be a protonated acyclic species. Reaction of this early intermediate with water produces intermediate A, while reaction with FAL produces intermediate B.

Experimental and Theoretical Studies of the Acid-Catalyzed Conversion of Furfuryl Alcohol to Levulinic Acid in Aqueous Solution

Energy Technology Data Exchange (ETDEWEB)

Gonzalez Maldonado, Gretchen; Assary, Rajeev S.; Dumesic, James A; Curtiss, Larry A

2012-01-01

The conversion of furfuryl alcohol (FAL) to levulinic acid over Amberlyst^TM 15 in aqueous media was investigated using a combination of liquid chromatography-mass spectrometry (LC-MS) measurements, isotopic labeling studies, nuclear magnetic resonance (NMR) spectroscopy, and ab initio quantum chemical calculations using the G4MP2 method. The results of these combined studies showed that one of the major reaction pathways takes place via a geminal diol species (4,5,5-trihydroxypentan-2-one, denoted as intermediate A), formed by the addition of two water molecules to FAL, where two of the oxygen atoms from FAL are retained. This geminal diol species can also be produced from another intermediate found to be a dimer-like species, denoted as intermediate B. This dimer-like species is formed at the early stages of reaction, and it can also be converted to intermediate A, indicating that intermediate B is the product of the reaction of FAL with another early intermediate. Quantum chemical calculations suggested this to be a protonated acyclic species. Reaction of this early intermediate with water produces intermediate A, while reaction with FAL produces intermediate B.

Regeneration of an aqueous solution from an acid gas absorption process by matrix stripping

Science.gov (United States)

Rochelle, Gary T [Austin, TX; Oyenekan, Babatunde A [Katy, TX

2011-03-08

Carbon dioxide and other acid gases are removed from gaseous streams using aqueous absorption and stripping processes. By replacing the conventional stripper used to regenerate the aqueous solvent and capture the acid gas with a matrix stripping configuration, less energy is consumed. The matrix stripping configuration uses two or more reboiled strippers at different pressures. The rich feed from the absorption equipment is split among the strippers, and partially regenerated solvent from the highest pressure stripper flows to the middle of sequentially lower pressure strippers in a "matrix" pattern. By selecting certain parameters of the matrix stripping configuration such that the total energy required by the strippers to achieve a desired percentage of acid gas removal from the gaseous stream is minimized, further energy savings can be realized.

Volumetric properties of aqueous solutions of glutaric acid

International Nuclear Information System (INIS)

Ben-Hamo, Meyrav; Apelblat, Alexander; Manzurola, Emanuel

2007-01-01

Densities of aqueous solutions with molalities up to 6 mol . kg -1 were determined at 5 K temperature intervals, from T = 288.15 K to T = 333.15 K. Densities served to evaluate the apparent molar volumes, V 2,φ (m, T), the cubic expansion coefficients, α(m, T), and the changes of isobaric heat capacities with respect to pressure, (∂C P /∂P) T,m . They were qualitatively correlated with the changes in the structure of water when glutaric acid is dissolved in it

Spectroscopic and redox properties of curium and californium ions in concentrated aqueous carbonate-bicarbonate media

International Nuclear Information System (INIS)

Hobart, D.E.; Varlashkin, P.G.; Samhoun, K.; Haire, R.G.; Peterson, J.R.

1983-01-01

Multimilligram quantities of trivalent curium-248 and californium-249 were investigated by absorption spectroscopy, cyclic voltammetry, and bulk solution electrolysis in concentrated aqueous carbonate-bicarbonate solution. Actinide concentrations between 10 -4 and 10 -2 M were studied in 2 M sodium carbonate and 5.5 M potassium carbonate solutions at pH values from 8 to 14. The solution absorption spectra of Cm(III) and Cf(III) in carbonate media are presented for the first time and compared to literature spectra of these species in noncomplexing aqueous solution. It was anticipated that carbonate complexation of the actinide ions could provide a sufficient negative shift in the formal potentials of the M(IV)/M(III) couples of Cm and Cf to permit the generation and stabilization of their tetravalent states in aqueous carbonate-bicarbonate medium. No conclusive evidence was found in the present work to indicate the existence of any higher oxidation states of curium or californium in carbonate solution. Some possible reasons for our inability to generate and detect oxidized species of curium and californium in this medium are discussed

Recovery of homogeneous polyoxometallate catalysts from aqueous and organic media by a mesoporous ceramic membrane without loss of catalytic activity.

Science.gov (United States)

Roy Chowdhury, Sankhanilay; Witte, Peter T; Blank, Dave H A; Alsters, Paul L; Ten Elshof, Johan E

2006-04-03

The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous gamma-alumina membranes is reported. The recovery of Q(12)[WZn(3)(ZnW(9)O(34))(2)] (Q=[MeN(n-C(8)H(17))(3)](+)) from toluene-based media was quantitative within experimental error, while up to 97 % of Na(12)[WZn(3)(ZnW(9)O(34))(2)] could be recovered from water. The toluene-soluble POM catalyst was used repeatedly in the conversion of cyclooctene to cyclooctene oxide and separated from the product mixture after each reaction. The catalytic activity increased steadily with the number of times that the catalyst had been recycled, which was attributed to partial removal of the excess QCl that is known to have a negative influence on the catalytic activity. Differences in the permeability of the membrane for different liquid media can be attributed to viscosity differences and/or capillary condensation effects. The influence of membrane pore radius on permeability and recovery is discussed.

Adsorption of Copper Ion using Acrylic Acid-g-Polyaniline in Aqueous Solution

Science.gov (United States)

Kamarudin, Sabariah; Mohammad, Masita

2018-04-01

A conductive polymer, polyaniline (PANI) has unique electrical behaviour, stable in the environment, easy synthesis and have wide application in various fields. Modification of PANI in order to improve its adsorption capacity has been done. In this study, the polyaniline-grafted acrylic acid has been prepared and followed by adsorption of copper ion in aqueous solution. Acrylic acid, PANI and acrylic acid-g-polyaniline (Aag-PANI) were characterized by FTIR and SEM to determine its characteristic. The adsorption capacity was investigated to study the removal capacity of Cu ion from aqueous solution. Two parameters were selected which are pH (2, 4 and 6) and initial metal ion concentration (50 mg/L, 100 mg/L and 200 mg/L). The maximum adsorption capacity for PANI and Aag-PANI are 1.7 mg/g and 64.6 mg/g, respectively, at an initial concentration of 100 mg/L. The Langmuir adsorption isotherm model and Freundlich adsorption isotherm model have been used and showed that it is heterolayer adsorption by follows the Freundlich isotherm model.

Influence of enzymes on the oil extraction processes in aqueous media

Directory of Open Access Journals (Sweden)

Ricochon Guillaume

2010-11-01

Full Text Available The methods of oil aqueous extraction process (AEP assisted by enzymes are, over the last 50 years, an alternative designed to replace traditional methods of extraction using organic solvents. To extract the oil using an AEP, the use of specific enzymes, able to hydrolyze some or all components of seeds, can significantly increase the yields of extraction. Hydrolyzing the different constituents of cell walls (cellulose, hemicellulose, pectins, proteins, etc., enzymes are able to enhance the liberation of the oil. A number of physico-chemical parameters must also be considered for the better expression of the enzymatic mixture, while maintaining the quality of oils and meals. This article presents the various factors influencing the release of oil in aqueous media and the main results obtained by this process on various substrates.

Pulse electrodeposition of Pt and Pt–Ru methanol-oxidation nanocatalysts onto carbon nanotubes in citric acid aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Chou, Huei-Yu [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Hsieh, Chien-Kuo [Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan, ROC (China); Tsai, Ming-Chi; Wei, Yu-Hsuan; Yeh, Tsung-Kuang [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China); Tsai, Chuen-Horng, E-mail: tsai@aec.gov.tw [Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC (China)

2015-06-01

In this study, platinum nanoparticle/carbon nanotube (Pt NP/CNT) and platinum–ruthenium nanoparticle (Pt–Ru NP/CNT) hybrid nanocatalysts were prepared by the pulse-electrodeposition method in different aqueous solutions containing citric acid (CA) or sulfuric acid (SA). The electrocatalytic properties of the Pt NP/CNT and Pt–Ru NP/CNT electrodes prepared using different aqueous solutions were investigated for methanol oxidation. The results show that the electrochemical mass activities of these hybrid nanocatalysts prepared in the CA aqueous solution were increased by factors of 1.46 and 2.77 for Pt NPs and Pt–Ru NPs, respectively, compared with those prepared in SA aqueous solutions using the same procedure. These increased mass activities are attributed to the CA playing dual roles as both a stabilizing agent and a particle size reducing agent in the aqueous solutions. The approach developed in this work enables further reductions in the particle sizes of noble-metal nanocatalysts. - Highlights: • Pulse-electrodeposition of Pt or Pt–Ru nanoparticles on carbon nanotubes • Carbon nanotubes used as a catalyst-supporting material • Citric acid used as reducing agent in the aqueous electrodeposition solutions • Electrochemical activity for methanol oxidation improved by a factor of 1.46 to 2.77.

Polarographic studies about indium (III) behaviour in aqueous media of sodium azide

International Nuclear Information System (INIS)

Tokoro, R.

1988-01-01

The present study shows some polarographic behavior of indium (III) in azide media that is close those observed in a thiocyanate solution. The presence of azide ligand decreases the overpotential in the discharge of indium whose catalytic character can be explained by formation of an azide bridge between electrode and indium (III) increasing the speed of electron transfer. The discharge of indium in azide media is diffusion controlled. As the azide concentration is increased the half wave potential displaces in the cathodic direction. This displacement is due to complex formation. The number of electrons, n, involved in the total process was estimates by the reversible polarographic equation to be 2,7. The potentiostatic coulometry of indium in azide/hydrazoic acid buffer showed a catalytic process where the chemistry regeneration was performed by reaction of hydrazoic acid and indium amalgam. The electrochemistry evidence was the constancy of current as the electrolysis proceeded. The chemistry aspect was the presence of ammonium cation in electrolysed solution. The catalytic process with chemistry regeneration and the formation of a bridge by azide could explain the higher value of current in azide media compared to perchlorate solution. (author) [pt

Removal of CdTe in acidic media by magnetic ion-exchange resin: A potential recycling methodology for cadmium telluride photovoltaic waste

Energy Technology Data Exchange (ETDEWEB)

Zhang, Teng, E-mail: zhangteng@mail.iee.ac.cn; Dong, Zebin; Qu, Fei; Ding, Fazhu; Peng, Xingyu; Wang, Hongyan; Gu, Hongwei

2014-08-30

Highlights: • Sulfonated magnetic microsphere was prepared as one strong acid cation-exchange resin. • Cd and Te can be removed directly from the highly acidic leaching solution of CdTe. • Good chemical stability, fast adsorbing rate and quick magnetic separation in strong acidic media. • A potential path for recycling CdTe photovoltaic waste. - Abstract: Sulfonated magnetic microspheres (PSt-DVB-SNa MPs) have been successfully prepared as adsorbents via an aqueous suspension polymerization of styrene-divinylbenzene and a sulfonation reaction successively. The resulting adsorbents were confirmed by means of Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS) and vibrating sample magnetometer (VSM). The leaching process of CdTe was optimized, and the removal efficiency of Cd and Te from the leaching solution was investigated. The adsorbents could directly remove all cations of Cd and Te from a highly acidic leaching solution of CdTe. The adsorption process for Cd and Te reached equilibrium in a few minutes and this process highly depended on the dosage of adsorbents and the affinity of sulfonate groups with cations. Because of its good adsorption capacity in strong acidic media, high adsorbing rate, and efficient magnetic separation from the solution, PSt-DVB-SNa MPs is expected to be an ideal material for the recycling of CdTe photovoltaic waste.

VOLTAMMETRY OF AQUEOUS CHLOROAURIC ACID WITH HANGING MERCURY DROP ELECTRODE

Czech Academy of Sciences Publication Activity Database

Korshunov, A.; Josypčuk, Bohdan; Heyrovský, Michael

2011-01-01

Roč. 76, č. 7 (2011), s. 929-936 ISSN 0010-0765 R&D Projects: GA ČR GAP206/11/1638; GA AV ČR IAA400400806; GA MŠk(CZ) LC06063 Institutional research plan: CEZ:AV0Z40400503 Keywords : aqueous chloauric acid * voltammetry * hanging mercury drop electrode Subject RIV: CG - Electrochemistry Impact factor: 1.283, year: 2011

Volumetric studies of some amino acids in binary aqueous solutions ...

Indian Academy of Sciences (India)

Unknown

0 values of glycine, L-alanine, and L-valine in aqueous MgCl2⋅6H2O solutions at. 298⋅15 K in order to describe the temperature dependence behaviour of partial molar quantities. Group contributions to partial molar volumes have been determined for the amino acids. The trends of transfer volumes (∆Vφ. 0) have been ...

Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Tan, Huaping, E-mail: hptan@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Hu, Xiaohong [School of Material Engineering, Jinling Institute of Technology, Nanjing (China)

2015-11-01

A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion.

Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

International Nuclear Information System (INIS)

Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

2015-01-01

A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion

Volumetric properties of aqueous solutions of glutaric acid

Energy Technology Data Exchange (ETDEWEB)

Ben-Hamo, Meyrav [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel)]. E-mail: apelblat@bgu.ac.il; Manzurola, Emanuel [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel)

2007-07-15

Densities of aqueous solutions with molalities up to 6 mol . kg{sup -1} were determined at 5 K temperature intervals, from T = 288.15 K to T = 333.15 K. Densities served to evaluate the apparent molar volumes, V {sub 2,{phi}}(m, T), the cubic expansion coefficients, {alpha}(m, T), and the changes of isobaric heat capacities with respect to pressure, ({partial_derivative}C {sub P}/{partial_derivative}P) {sub T,m}. They were qualitatively correlated with the changes in the structure of water when glutaric acid is dissolved in it.

Ascorbic acid concentrations in aqueous humor after systemic vitamin C supplementation in patients with cataract: pilot study.

Science.gov (United States)

Hah, Young-Sool; Chung, Hye Jin; Sontakke, Sneha B; Chung, In-Young; Ju, Sunmi; Seo, Seong-Wook; Yoo, Ji-Myong; Kim, Seong-Jae

2017-07-11

To measure ascorbic acid concentration in aqueous humor of patients with cataract after oral or intravenous vitamin C supplementation. Forty-two eyes of 42 patients with senile cataract who underwent uncomplicated cataract surgery were enrolled. Patients (n = 14 each) were administered oral vitamin C (2 g), intravenous vitamin C (20 g) or no treatment (control group) on the day before surgery. Samples of aqueous humor (0.1 cm 3 ) were obtained by anterior chamber aspiration at the beginning of surgery and stored at -80 °C. Ascorbic acid concentration in aqueous humor was measured by high-pressure liquid chromatography. The mean age at surgery was 62.5 years, with no difference among the three groups. The mean ± standard deviation concentrations of ascorbic acid in aqueous humor in the control and oral and intravenous vitamin C groups were 1347 ± 331 μmol/L, 1859 ± 408 μmol/L and 2387 ± 445 μmol/L, respectively. Ascorbic acid concentration was significantly lower in the control than in the oral (P humor is increased by systemic vitamin C supplementation, with intravenous administration being more effective than oral administration.

Kinetics of Oxidation of 3-Benzoylpropionic Acid by N-Bromoacetamide in Aqueous Acetic Acid Medium

Directory of Open Access Journals (Sweden)

N. A. Mohamed Farook

2011-01-01

Full Text Available The kinetics of oxidation of 3-benzoylpropionic acid (KA with N-bromoacetamide (NBA have been studied potentiometrically in 50:50 (v/v aqueous acetic acid medium at 298 K The reaction was first order each with respect to [KA], [NBA] and [H+]. The main product of the oxidation is the corresponding carboxylic acid. The rate decreases with the addition of acetamide, one of the products of the reaction. Variation in ionic strength of the reaction medium has no significant effect on the rate of oxidation. But the rate of the reaction is enhanced by lowering the dielectric constant of the reaction medium. A mechanism consistent with observed results have been proposed and the related rate law was deduced.

Thermodynamic modeling of acidic gas solubility in aqueous solutions of MEA, MDEA and MEA-MDEA blends

DEFF Research Database (Denmark)

Vrachnos, Ath.; Kontogeorgis, Georgios; Voutsas, EC

2006-01-01

and extended in this study to the absorption of carbon dioxide into aqueous monoethanolamine (MEA) solutions and aqueous MDEA-MEA blends. The results of the model are compared with experimental data taken from the literature. Very satisfactory predictions of acidic gas vapor-liquid equilibrium over MDEA, MEA...

49 CFR 173.195 - Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution).

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrogen cyanide, anhydrous, stabilized... Hazardous Materials Other Than Class 1 and Class 7 § 173.195 Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution). (a) Hydrogen cyanide, anhydrous, stabilized, must be packed in...

Gas chromatography/isotope ratio mass spectrometry: analysis of methanol, ethanol and acetic acid by direct injection of aqueous alcoholic and acetic acid samples.

Science.gov (United States)

Ai, Guomin; Sun, Tong; Dong, Xiuzhu

2014-08-15

Methanol, ethanol, and acetic acid are not easily extracted from aqueous samples and are susceptible to isotope fractionation in gas chromatography/isotope ratio mass spectrometry (GC/IRMS) analysis. Developing a direct dilution GC/IRMS method for aqueous samples, by adjusting the sample concentrations in common solvents to be similar to each other and using a fixed GC split ratio, is very convenient and important because any linearity effects caused by amount-dependent isotope fractionation can be avoided. The suitability of acetonitrile and acetone solvents for the GC/IRMS analysis of pure methanol, ethanol and acetic acid, and commercial liquor and vinegar samples was evaluated using n-hexane and water as control solvents. All the solvents including water were separated from the analyte on a HP-INNOWAX column and were diverted away from the combustion interface. The influence of liquor matrix on the ethanol GC/IRMS analyses was evaluated by adding pure ethanol to liquor samples. Acetonitrile and acetone gave similar δ(13) C values for pure ethanol and pure acetic acid to those obtained in water and n-hexane, and also gave similar δ(13) C values of ethanol in liquor and acetic acid in white vinegar to that obtained in water. For methanol analysis, acetonitrile and refined acetone gave similar δ(13) C values to that obtained in water, but n-hexane was not a suitable solvent. In addition, isotopic fractionation caused by solvent and solute interactions was observed. We recommend using acetonitrile for the GC/IRMS analysis of aqueous alcoholic samples, and acetone for the analysis of aqueous acetic acid samples. This direct dilution method can provide high accurate and precise GC/IRMS analysis of the relative changes in δ(13) C values of methanol, ethanol, and acetic acid. Copyright © 2014 John Wiley & Sons, Ltd.

Co-extraction and co-stripping of U(VI) and Pu(IV) using tri-iso-amyl phosphate and tri-n-butyl phosphate in n-dodecane from nitric acid media under high loading conditions

Energy Technology Data Exchange (ETDEWEB)

Sreenivasulu, Balija; Suresh, Ammath; Sivaraman, Nagarajan; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

2016-08-01

The extraction of Pu(IV) using 1.1 M solution of tri-iso-amyl phosphate (TiAP)/n-dodecane (DD) from plutonium nitrate solutions in nitric acid media was examined as a function of equilibrium aqueous phase metal ion concentration and equilibrium aqueous phase acidity at 303 K. The nitric acid concentration in the organic phase was measured as a function of equilibrium organic phase plutonium concentration. The co-extraction of U(VI) and Pu(IV) was studied using 1.1 M TiAP/DD system as a function of their equilibrium aqueous phase metal ion concentration and compared with 1.1 M tri-n-butyl phosphate (TBP)/n-DD system under identical conditions. Co-extraction and co-stripping of U(VI) and Pu(IV) were studied using 1.1 M TiAP/DD and 1.1 M TBP/DD systems in cross current mode to evaluate the number of stages required for the extraction and stripping of heavy metal ions (uranium and plutonium). The extraction and stripping efficiencies were calculated for both the systems. The saturation limit of the organic phase was also established in these studies.

Co-extraction and co-stripping of U(VI) and Pu(IV) using tri-iso-amyl phosphate and tri-n-butyl phosphate in n-dodecane from nitric acid media under high loading conditions

International Nuclear Information System (INIS)

Sreenivasulu, Balija; Suresh, Ammath; Sivaraman, Nagarajan; Rao, P.R. Vasudeva

2016-01-01

The extraction of Pu(IV) using 1.1 M solution of tri-iso-amyl phosphate (TiAP)/n-dodecane (DD) from plutonium nitrate solutions in nitric acid media was examined as a function of equilibrium aqueous phase metal ion concentration and equilibrium aqueous phase acidity at 303 K. The nitric acid concentration in the organic phase was measured as a function of equilibrium organic phase plutonium concentration. The co-extraction of U(VI) and Pu(IV) was studied using 1.1 M TiAP/DD system as a function of their equilibrium aqueous phase metal ion concentration and compared with 1.1 M tri-n-butyl phosphate (TBP)/n-DD system under identical conditions. Co-extraction and co-stripping of U(VI) and Pu(IV) were studied using 1.1 M TiAP/DD and 1.1 M TBP/DD systems in cross current mode to evaluate the number of stages required for the extraction and stripping of heavy metal ions (uranium and plutonium). The extraction and stripping efficiencies were calculated for both the systems. The saturation limit of the organic phase was also established in these studies.

Ultrasound promoted one-pot synthesis of 2-amino-4,8-dihydropyrano[3,2-b]pyran-3-carbonitrile scaffolds in aqueous media: a complementary 'green chemistry' tool to organic synthesis.

Science.gov (United States)

Banitaba, Sayed Hossein; Safari, Javad; Khalili, Shiva Dehghan

2013-01-01

A green and simple approach to assembling of 2-amino-4,8-dihydropyrano[3,2-b]pyran-3-carbonitrile scaffolds via three-component reaction of kojic acid, malononitrile, and aromatic aldehydes in aqueous media under ultrasound irradiation is described. The combinatorial synthesis was achieved for this methodology with applying ultrasound irradiation while making use of water as green solvent. In comparison to conventional methods, experimental simplicity, good functional group tolerance, excellent yields, short routine, and selectivity without the need for a transition metal or base catalyst are prominent features of this green procedure. Copyright © 2012 Elsevier B.V. All rights reserved.

Acid-base equilibrium in aqueous solutions of 1,3-dimethylbarbituric acid as studied by 13C NMR spectroscopy

Science.gov (United States)

Gryff-Keller, A.; Kraska-Dziadecka, A.

2011-12-01

13C NMR spectra of 1,3-dimethylbarbituric acid in aqueous solutions of various acidities and for various solute concentrations have been recorded and interpreted. The spectra recorded at pH = 2 and below contain the signals of the neutral solute molecule exclusively, while the ones recorded at pH = 7 and above only the signals of the appropriate anion, which has been confirmed by theoretical GIAO-DFT calculations. The signals in the spectra recorded for solutions of pH pH variation have been observed for the parent barbituric acid.

Desalination of aqueous media using ionic liquids

NARCIS (Netherlands)

2014-01-01

The present invention relates to a method for extracting metal and/or metalloid ions from an aqueous medium, comprising the steps of: a) mixing the aqueous medium with an ionic liquid comprising an aliphatic carboxylate anion having at least one unsaturated carbon-carbon bond, or and/or with a

Surface grafting of cellulose nanocrystals with poly(ethylene oxide) in aqueous media.

Science.gov (United States)

Kloser, Elisabeth; Gray, Derek G

2010-08-17

Aqueous suspensions of poly(ethylene oxide)-grafted nanocrystalline cellulose (PEO-grafted NCC) were prepared in order to achieve steric instead of electrostatic stabilization. A two-step process was employed: in the first step NCC suspensions prepared by sulfuric acid hydrolysis were desulfated with sodium hydroxide, and in the second step the surfaces of the crystals were functionalized with epoxy-terminated poly(ethylene oxide) (PEO epoxide) under alkaline conditions. The PEO-grafted samples were analyzed by conductometric titration, ATR-IR, solid-state NMR, MALDI-TOF MS, SEC MALLS, and AFM. The covalent nature of the linkage was confirmed by weight increase and MALDI-TOF analysis. The PEO-grafted cellulose nanocrystals (CNCs) formed a stable colloidal suspension that remained well dispersed, while the desulfated nanoparticles aggregated and precipitated. Upon concentration of the PEO-grafted aqueous NCC suspension, a chiral nematic phase was observed.

TiO{sub 2}-based photocatalytic disinfection of microbes in aqueous media: A review

Energy Technology Data Exchange (ETDEWEB)

Laxma Reddy, P.Venkata [Program in Environmental Science and Engineering, University of Texas El Paso, El Paso, TX 799038 (United States); Kavitha, Beluri [Department of Pharmacology, Kamineni Institute of Medical Sciences, Dr. NTRUHS, Vijayawada, Andhra Pradesh 520008 (India); Kumar Reddy, Police Anil [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 38541 (Korea, Republic of); Kim, Ki-Hyun, E-mail: kkim61@hanyang.ac.kr [Department of Civil & Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 04763 (Korea, Republic of)

2017-04-15

The TiO{sub 2} based photocatalyst has great potential for the disinfection/inactivation of harmful pathogens (such as E.coli in aqueous media) along with its well-known usefulness on various chemical pollutants. The disinfection property of TiO{sub 2} is primarily attributed to surface generation of reactive oxygen species (ROS) as well as free metal ions formation. Furthermore, its disinfection capacity and overall performance can be significantly improved through modifications of the TiO{sub 2} material. In this review, we provide a brief survey on the effect of various TiO{sub 2} materials in the disinfection of a wide range of environmentally harmful microbial pathogens (e.g., bacteria, fungi, algae, and viruses) in aqueous media. The influencing factors (such as reactor design, water chemistry, and TiO{sub 2} modifications) of such processes are discussed along with the mechanisms of such disinfection. It is believed that the combined application of disinfection and decontamination will greatly enhance the utilization of TiO{sub 2} photocatalyst as a potential alternative to conventional methods of water purification. - Highlights: • The advent of industrialization jeopardized the quality of drinking water. • TiO{sub 2} photocatalysis holds promise both in the degradation of pollutants and for disinfection. • The applicability of TiO{sub 2}-based decontamination is explored for microbial disinfection. • Here we provide a comprehensive review on titania-based photocatalysts for disinfection.

Detection of biologically important anions in aqueous media by dicationic azaborines bearing ammonio or phosphonio groups.

Science.gov (United States)

Agou, Tomohiro; Sekine, Masaki; Kobayashi, Junji; Kawashima, Takayuki

2009-01-01

New cationic triarylboranes bearing ammonio or phosphonio groups on the periphery were synthesized from a common intermediate, a dibromodibenzoazaborine. These cationic molecules are soluble in highly polar organic solvents as well as water, and they exhibit strong light absorption and photoluminescence emission in water. Complexation of the cationic azaborines with fluoride and cyanide ions in aqueous media proceeded and could be monitored by NMR, UV/Vis, and fluorescence spectroscopy.

Density, viscosity, and N2O solubility of aqueous amino acid salt and amine amino acid salt solutions

International Nuclear Information System (INIS)

Aronu, Ugochukwu E.; Hartono, Ardi; Svendsen, Hallvard F.

2012-01-01

Highlights: ► Density of amino acid salt and amine amino acid salt. ► Viscosity of amino acid salt and amine amino acid salt. ► Henry’s law constant/N 2 O solubility of amino acid salt and amine amino acid salt. ► Schumpe model. Correlations for density, viscosity, and N 2 O solubility. - Abstract: Physicochemical properties of aqueous amino acid salt (AAS), potassium salt of sarcosine (KSAR) and aqueous amine amino acid salt (AAAS), 3-(methylamino)propylamine/sarcosine (SARMAPA) have been studied. Densities of KSAR were measured for sarcosine mole fraction 0.02 to 0.25 for temperature range 298.15 K to 353.15 K, the viscosities were measured for 0.02 to 0.10 mole fraction sarcosine (293.15 K to 343.15 K) while the N 2 O solubilities were measured from 0.02 to 0.10 mole fraction sarcosine solutions (298.15 K to 363.15 K). Densities of SARMAPA were measured for sarcosine mole fraction 0.02 to 0.23 for temperature range (298.15 K to 353.15 K), viscosities were measured for 0.02 to 0.16 mole fraction sarcosine (293.15 K to 343.15 K) while the N 2 O solubilities were measured from 0.02 to 0.16 mole fraction sarcosine solutions (298.15 K to 343.15 K). Experimental results were correlated well with empirical correlations and N 2 O solubility results for KSAR were predicted adequately by a Schumpe model. The solubilities of N 2 O in AAS and AAAS are significantly lower than values for amines. The solubilities vary as: amine > AAAS > AAS.

Reactive transport of aqueous protons in porous media

KAUST Repository

McNeece, Colin J.

2016-10-09

The sorption of protons determines the surface charge of natural media and is therefore a first-order control on contaminant transport. Significant effort has been extended to develop chemical models that quantify the sorption of protons at the mineral surface. To compare these models’ effect on predicted proton transport, we present analytic solutions for column experiments through silica sand. Reaction front morphology is controlled by the functional relationship between the total sorbed and total aqueous proton concentrations. An inflection point in this function near neutral pH leads to a reversal in the classic front formation mechanism under basic conditions, such that proton desorption leads to a self-sharpening front, while adsorption leads to a spreading front. A composite reaction front comprising both a spreading and self-sharpening segment can occur when the injected and initial concentrations straddle the inflection point. This behavior is unique in single component reactive transport and arises due to the auto-ionization of water rather than electrostatic interactions at the mineral surface. We derive a regime diagram illustrating conditions under which different fronts occur, highlighting areas where model predictions diverge. Chemical models are then compared and validated against a systematic set of column experiments.

Suzuki-Miyaura cross-coupling reactions in aqueous media: green and sustainable syntheses of biaryls.

Science.gov (United States)

Polshettiwar, Vivek; Decottignies, Audrey; Len, Christophe; Fihri, Aziz

2010-05-25

Carbon-carbon cross-coupling reactions are among the most important processes in organic chemistry, and Suzuki-Miyaura reactions are among the most widely used protocols for the formation of carbon-carbon bonds. These reactions are generally catalyzed by soluble palladium complexes with various ligands. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance. This Review will summarize various recently developed significant methods by which the Suzuki-Miyaura coupling was conducted in aqueous media, and analyzes if they are "real green" protocols.

Pitting morphologies of zirconium base alloys in aqueous and non aqueous chloride media

International Nuclear Information System (INIS)

Palit, G.C.; Gadiyar, H.S.

1988-01-01

Pitting morphology of zirconium and Zr-Cr alloys in aqueous chloride and nonaqueous methanol + 0.4 per cent HCl solution was investigated and observed to follow different modes in these two environments. While in aqueous chloride solution pitting was transgranular and randomly oriented, in methanol-chloride solution pits were observed to initiate and propagate along the grain boundaries. In aqueous chloride solution very irregular and sponge like zirconium metal was formed inside the pit while in methanol-chloride solution the pits were crystallographic in nature. Optical microscopy has revealed that pits preferentially initiate and propagate along scratch line in aqueous chloride solution, but such was not the case in nonaqueous methanol-chloride solution. The nature and the mechanism operating in the catastropic failure of these materials are investigated. (author). 10 refs., 11 figs

Vine-shoot waste aqueous extract applied as foliar fertilizer to grapevines: Effect on amino acids and fermentative volatile content.

Science.gov (United States)

Sánchez-Gómez, R; Garde-Cerdán, T; Zalacain, A; Garcia, R; Cabrita, M J; Salinas, M R

2016-04-15

The aim of this work was to study the influence of foliar applications of different wood aqueous extracts on the amino acid content of musts and wines from Airén variety; and to study their relationship with the volatile compounds formed during alcoholic fermentation. For this purpose, the foliar treatments proposed were a vine-shoot aqueous extract applied in one and two times, and an oak extract which was only applied once. Results obtained show the potential of Airén vine-shoot waste aqueous extracts to be used as foliar fertilizer, enhancing the wine amino acid content especially when they were applied once. Similar results were observed with the aqueous oak extract. Regarding wine fermentative volatile compounds, there is a close relationship between musts and their wines amino acid content allowing us to discuss about the role of proline during the alcoholic fermentation and the generation of certain volatiles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mass spectrometric detection of proteins in non-aqueous media : the case of prion proteins in biodiesel

Energy Technology Data Exchange (ETDEWEB)

Douma, M.D.; Kerr, G.M.; Brown, R.S.; Keller, B.O.; Oleschuk, R.D. [Queen' s Univ., Kingston, ON (Canada). Dept. of Chemistry

2008-08-15

This paper presented a filtration method for detecting protein traces in non-aqueous media. The extraction technique used a mixture of acetonitrile, non-ionic detergent and water along with filter disks with embedded C{sub 8}-modified silica particles to capture the proteins from non-aqueous samples. The extraction process was then followed by an elution of the protein from the filter disk and direct mass spectrometric detection and tryptic digestion with peptide mapping and MS/MS fragmentation of protein-specific peptides. The method was used to detect prion proteins in spiked biodiesel samples. A tryptic peptide with the sequence YGQGSPGGNR was used for unambiguous identification. Results of the study showed that the method is suitable for the large-scale testing of protein impurities in tallow-based biodiesel production processes. 33 refs., 6 figs.

Acetanilide interaction with hydriodic acid in aqueous solutions at 20 and 40 deg C

International Nuclear Information System (INIS)

Erkasov, R.Sh.; Nurakhmetov, N.I.

1990-01-01

Isothermal method was used to study acetanilide solubility in aqueous solutions of hydriodic acid at 20 and 40 deg C. formation of two new anhydrous compounds of 2:1 and 1:1 compositions (anilide: acid molar ratio) was established. Temperature and concentration boundaries of solid phase formation were established for these compounds. Their IR spectroscopic investigation was conducted

Dissolution mechanism of aluminum hydroxides in acid media

Science.gov (United States)

Lainer, Yu. A.; Gorichev, I. G.; Tuzhilin, A. S.; Gololobova, E. G.

2008-08-01

The effects of the concentration, temperature, and potential at the hydroxide/electrolyte interface on the aluminum hydroxide dissolution in sulfuric, hydrochloric, and perchloric acids are studied. The limiting stage of the aluminum hydroxide dissolution in the acids is found to be the transition of the complexes that form on the aluminum hydroxide surface from the solid phase into the solution. The results of the calculation of the acid-base equilibrium constants at the oxide (hydroxide)/solution interface using the experimental data on the potentiometric titration of Al2O3 and AlOOH suspensions are analyzed. A mechanism is proposed for the dissolution of aluminum hydroxides in acid media.

Tandem Aldol-Michael Reactions in Aqueous Diethylamine Medium: A Greener and Efficient Approach to Bis-Pyrimidine Derivatives

Directory of Open Access Journals (Sweden)

Abdullah M. Al-Majid

2013-12-01

Full Text Available A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a–i and 4a–e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%–99%.

Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

International Nuclear Information System (INIS)

Celik, Z. Ceylan; Can, B.Z.; Kocakerim, M. Muhtar

2008-01-01

In this study, the removal of boric acid from aqueous solution by activated carbon impregnated with salicylic acid was studied in batch system. pH, adsorbent amount, initial boron concentration, temperature, shaking rate and salicylic acid film thickness were chosen as parameters. Boron removal efficiencies increased with increasing adsorbent amount, temperature and pH, decreasing initial boron concentration. As thickness of salicylic acid film on activated carbon becomes thin up to 0.088 nm, the efficiency increased, and then, the efficiency decreased with becoming thinner than 0.088 nm of salicylic acid film. Shaking rate was no effect on removal efficiency. In result, it was determined that the use of salicylic acid as an impregnant for activated carbon led to the increase of the amount of boron adsorbed. A lactone ring, being the most appropriate conformation, forms between boric acid and -COOH and -OH groups of salicylic acid

Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

Energy Technology Data Exchange (ETDEWEB)

Celik, Z. Ceylan [Department of Environmental Engineering, Atatuerk University, Faculty of Engineering, Erzurum (Turkey)], E-mail: zcelik@atauni.edu.tr; Can, B.Z. [Department of Environmental Engineering, Atatuerk University, Faculty of Engineering, Erzurum (Turkey); Kocakerim, M. Muhtar [Department of Chemical Engineering, Atatuerk University, Faculty of Engineering, 25240 Erzurum (Turkey)

2008-03-21

In this study, the removal of boric acid from aqueous solution by activated carbon impregnated with salicylic acid was studied in batch system. pH, adsorbent amount, initial boron concentration, temperature, shaking rate and salicylic acid film thickness were chosen as parameters. Boron removal efficiencies increased with increasing adsorbent amount, temperature and pH, decreasing initial boron concentration. As thickness of salicylic acid film on activated carbon becomes thin up to 0.088 nm, the efficiency increased, and then, the efficiency decreased with becoming thinner than 0.088 nm of salicylic acid film. Shaking rate was no effect on removal efficiency. In result, it was determined that the use of salicylic acid as an impregnant for activated carbon led to the increase of the amount of boron adsorbed. A lactone ring, being the most appropriate conformation, forms between boric acid and -COOH and -OH groups of salicylic acid.

Volumetric and viscometric studies of amino acids in L-ascorbic acid aqueous solutions at T = (293.15 to 323.15) K

International Nuclear Information System (INIS)

Jiang, Xiaofeng; Zhu, Chunying; Ma, Youguang

2014-01-01

Graphical abstract: The densities and viscosities of L-alanine in L-ascorbic acid aqueous solutions at T = 293.15 K. Highlights: • Densities and viscosities of five amino acids in L-ascorbic acid aqueous solutions were measured. • Based on the experimental data, a series of volumetric and viscometric parameters were calculated. • The group additivity analysis has been applied to analyze the V φ 0 and B-coefficients. -- Abstract: Densities and viscosities of glycine, L-alanine, L-valine, L-threonine and L-arginine in aqueous solutions of (0.0, 0.1, 0.2, 0.3 and 0.4) mol · kg −1 L-ascorbic acid have been measured at T = (293.15, 303.15, 313.15 and 323.15) K under atmospheric pressure. The apparent molar volumes (V φ ), limiting partial molar volumes (V φ 0 ), limiting partial molar volumes of transfer (Δ tr V φ 0 ) and limiting partial molar expansibilities (E 2 0 ) were computed by densities. The extended Jones–Dole equation was used to correlate the viscosities in order to obtain viscosity B-coefficients and the free energies of activation per mole of solvent (Δμ 1 0≠ ) and solute (Δμ 2 0≠ ) were also calculated. The contributions of zwitterionic end group (NH 3 + , COO − ), CH 2 group, OH group and CNHNHNH 2 group to V φ 0 and viscosity B-coefficients were obtained through the group additivity analysis

Corrosion control of vanadium in aqueous solutions by amino acids

International Nuclear Information System (INIS)

El-Rabiee, M.M.; Helal, N.H.; El-Hafez, Gh.M. Abd; Badawy, W.A.

2008-01-01

The electrochemical behavior of vanadium in amino acid free and amino acid containing aqueous solutions of different pH was studied using open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS). The corrosion current density, i corr , the corrosion potential, E corr and the corrosion resistance, R corr , were calculated. A group of amino acids, namely, glycine, alanine, valine, histidine, glutamic and cysteine has been investigated as environmentally safe inhibitors. The effect of Cl - on the corrosion inhibition efficiency especially in acid solutions was investigated. In neutral and basic solutions, the presence of amino acids increases the corrosion resistance of the metal. The electrochemical behavior of V before and after the corrosion inhibition process has shown that some amino acids like glutamic acid and histidine have promising corrosion inhibition efficiency at low concentration (≅25 mM). The inhibition efficiency (η) was found to depend on the structure of the amino acid and the constituents of the corrosive medium. The corrosion inhibition process is based on the adsorption of the amino acid molecules on the metal surface and the adsorption process follows the Freundlich isotherm. The adsorption free energy for valine on V in acidic solutions was found to be -9.4 kJ/mol which reveals strong physical adsorption of the amino acid molecules on the vanadium surface

Synthesis and characterization of ferrous phosphate (vivianite) and its behavior in aqueous media; Sintesis y caracterizacion del fosfato ferroso (vivianita) y su comportamiento en medio acuoso

Energy Technology Data Exchange (ETDEWEB)

Diaz F, J.C

2003-07-01

The synthesis and characterization of materials that can be useful in Environmental Chemistry is very important because their characteristics are exposed and its behavior in chemical phenomena as the sorption in aqueous media is understand to use it in the human being benefit. With the object of using, in a future, the octa hydrated ferrous phosphate (vivianite) as a potential candidate for matrix confinement in contention walls for the storage of radioactive waste of long half life, it was synthesized and it characterized physico chemically and their properties of surface of this compound were evaluated. Presently work was carried out the synthesis and structural characterization of the iron phosphate II by infrared spectroscopy with having Fourier transform, high vacuum scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, the BET multipoint surface area and Moessbauer spectroscopy; as well as, the determination between aqueous media of the isoelectric point and the density of sites of surface of the compound. The octa hydrated ferrous phosphate was obtained pure. The results indicate that the product corresponds to the prospective mineral, the vivianite. The thermal gravimetric analysis demonstrated that the ferrous phosphate is a stable salt after the lost of water. The isoelectric point is since an important parameter because allows to know the behavior of the surface of the material in aqueous systems, in this case the isoelectric point, of the octa hydrated ferrous phosphate, in distilled water is of pH 4.20 and in solution of potassium nitrate 0.5 M is of pH = 3.75. This indicates that the material has an amphoteric surface depending on the pH. On the other hand, the density of active sites of surface obtained by titrations acid-base is of 20 sites by nm{sup 2}. (Author)

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

Visualization data on the freezing process of micrometer-scaled aqueous citric acid drops

Directory of Open Access Journals (Sweden)

Anatoli Bogdan

2017-02-01

Full Text Available The visualization data (8 movies presented in this article are related to the research article entitled “Freezing and glass transitions upon cooling and warming and ice/freeze-concentration-solution morphology of emulsified aqueous citric acid” (A. Bogdan, M.J. Molina, H. Tenhu, 2016 [1]. The movies recorded in-situ with optical cryo-miscroscopy (OC-M demonstrate for the first time freezing processes that occur during the cooling and subsequent warming of emulsified micrometer-scaled aqueous citric acid (CA drops. The movies are made publicly available to enable critical or extended analyzes.

Study of the interaction metallic cation - ligand in concentrated phosphorus acid media

International Nuclear Information System (INIS)

Sefiani, N.; Azzi, M.; Hlaibi, M.; Kossair, A.

2005-01-01

The phosphoric acid is more and more used with a high purity. The recovery of recycling element (uranium, vanadium, rare earth...) and the elimination of toxic element (cadmium, molybdenum, lead...) contained in the phosphoric acid are generally realized by extraction or precipitation. It is then very important to understand these impurities behavior in the phosphoric media in order to control their elimination. In this work, the authors considered the presence of some metallic cations (V, Al, fe, U) and fluorides ions as impurity in concentrated phosphoric acid media. (A.L.B.)

NABTIT-a computer program for non-aqueous acid-base titration.

Science.gov (United States)

Budevsky, O; Zikolova, T; Tencheva, J

1988-11-01

A program NABTIT written in BASIC has been developed for the treatment of data (ml/mV) obtained from potentiometric acid-base titrations in non-aqueous solvents. No preliminary information on equilibrium constants is required for the input. The treatment of the data is based on known equations and uses least-squares procedures. The essence of the method is to determine the equivalence volume (V(e)) accurately, and to use the data acquired by adding titrant after V(e) for the pH*-calibration of the non-aqueous potentiometric cell. As a by-product or the calculations, the pK* value of the substance titrated is also obtained, and in some cases the autoprotolysis constant of the medium (pK*(s)). Good agreement between experiment and theory was found in the treatment of data obtained for water and methanol-water mixtures.

Uranium removal from acidic aqueous solutions by Saccharomyces cerevisiae, Debaryomyces hansenii, Kluyveromyces marxianus and Candida colliculosa

International Nuclear Information System (INIS)

Sarri, S.; Misaelides, P.; Papanikolaou, M.; Zamboulis, D.

2009-01-01

The sorption of uranium from acidic aqueous solutions (pH 4.5, C init = 10 to 1000 mg U/L) by Saccharomyces cerevisiae, Debaryomyces hansenii, Kluyveromyces marxianus and Candida colliculosa was investigated using a batch technique. The U-sorption onto Saccharomyces cerevisiae and Debaryomyces hansenii followed a Langmuir, while that onto Kluyveromyces marxianus and Candida colliculosa a Freundlich isotherm. The results demonstrated that all investigated biomasses could effectively remove uranium from acidic aqueous solutions. From all sorbents, Saccharomyces cerevisiae appeared to be the most effective with a maximum sorption capacity of 127.7 mg U/g dry biomass. (author)

High-Yield Production of Levulinic Acid from Pretreated Cow Dung in Dilute Acid Aqueous Solution

Directory of Open Access Journals (Sweden)

Jialei Su

2017-02-01

Full Text Available Agricultural waste cow dung was used as feedstock for the production of a high value–added chemical levulinic acid (LA in dilute acid aqueous solutions. A high LA yield of 338.9 g/kg was obtained from the pretreated cow dung, which was much higher than that obtained from the crude cow dung (135 g/kg, mainly attributed to the breakage of the lignin fraction in the lignocellulose structure of the cow dung by potassium hydroxide (KOH pretreatment, and thus enhanced the accessibility of cow dung to the acid sites in the catalytic reaction. Meanwhile, another value-added chemical formic acid could be obtained with a yield of ca. 160 g/kg in the process, implying a total production of ca. 500 g/kg yield for LA and formic acid from the pretreated cow dung with the proposed process. The developed process was shown to be tolerant to high initial substrate loading with a satisfied LA yield. This work provides a promising strategy for the value-increment utilization of liglocellulosic agricultural residues.

Electroactivity of cobalt and nickel glyoximes with regard to the electro-reduction of protons into molecular hydrogen in acidic media

Energy Technology Data Exchange (ETDEWEB)

Pantani, O.; Anxolabehere-Mallart, E.; Aukauloo, A. [Equipe de Chimie Inorganique, Institut de Chimie Moleculaire et des Materiaux d' Orsay, UMR 8182, Universite Paris Sud, bat 420, 91405 Orsay Cedex (France); Millet, P. [Equipe de Physico-Chimie de l' Etat Solide, Institut de Chimie Moleculaire et des Materiaux d' Orsay, UMR 8182, Universite Paris Sud, bat 420, 91405 Orsay Cedex (France)

2007-01-15

Water electrolysis is a key technological process for the production of hydrogen and the storage of intermittent and renewable energy sources. For domestic applications, the proton exchange membrane (PEM) process provides a safe and efficient way to split water into molecular hydrogen and oxygen but this technology, which requires platinum family electro-catalysts, remains too expensive. Molecular chemistry offers new opportunities for synthesizing alternative low-cost compounds, sufficiently stable in strong acidic media. In this paper, results obtained with different nickel and cobalt glyoximes are presented. They have been chemically (using UV-visible spectroscopy) and electrochemically (using cyclic voltammetry and spectro-electrochemistry) characterized. Their ability to electroreduce protons into molecular hydrogen from aqueous acidic solutions is discussed, the compounds being either dissolved in solution or immobilized at the surface of a solid electrode using recast Nafion{sup (R)} films in view of PEM applications. (author)

One-pot synthesis of Fe3O4@Chitosan-pSDCalix hybrid nanomaterial for the detection and removal of Hg2+ ion from aqueous media

Science.gov (United States)

Bhatti, Asif Ali; Oguz, Mehmet; Yilmaz, Mustafa

2018-03-01

New one pot mesoporous hybrid material containing iron nanoparticles fabricated with chitosan and p-sulfonato dansyl calix[4]arene composite (Fe3O4@Chitosan-pSDCalix) has been susccessfully synthesized. These mesoporous fluorescence iron nanoparticles were applied for the detection and removal of environmentally toxic Hg2+ ion from aqueous media. Different techniques were applied to confirm the preparation of Fe3O4@Chitosan-pSDCalix such as HRTEM, TGA/DTA, FTIR and XRD. Synthesized nanoparticles have average size of 17 nm with pore size of 0.19 nm as revealed from HRTEM images. Fluorescence study follow the photoinduced electron transfer process after addition of Hg2+ in the solution with decrease in intensity. Confocal microscope images were also acquired to confirm the presence of Hg2+ on nanoparticles. Adsorption study suggests that the removal of Hg2+ from aqueous media follows Langmuir adsorption isotherm. These studies suggest the synthesized Fe3O4@Chitosan-pSDCalix is an efficient hybrid material for the detection and removal of Hg2+ ion from aqueous media, and that it can also be used in biomolecules for the detection of toxic metal ions.

Estudo das interações entre o complexo polieletrolítico trimetilquitosana/carboximetilcelulose e Cu+2, ácido húmico e atrazina em solução aquosa Study of the interactions between the polyelectrolyte complex trimethylchitosan/carboxymethylcellulose and Cu+2, humic acid and atrazine in aqueous solution

Directory of Open Access Journals (Sweden)

Sergio P. Campana-Filho

2009-01-01

Full Text Available The polyelectrolyte complex (PEC resulting from the reaction of sodium carboxymethylcellulose (CMC and N,N,N-trimethylchitosan hydrochloride (TMQ was prepared and then characterized by infrared spectroscopy and energy dispersive X rays analysis. The interactions involving the PEC and Cu2+ ions, humic acid and atrazine in aqueous medium were studied. From the adsorption isotherms the maximum amount adsorbed (Xmax was determined as 61 mg Cu2+/g PEC, 171 mg humic acid/g PEC and 5 mg atrazine/g PEC. The results show that the CMC/TMQ complex has a high affinity for the studied species, indicating its potential application to remove them from aqueous media.

Thermodynamic studies on corrosion inhibition of aqueous solutions of amino/carboxylic acids toward copper by EMF measurement

International Nuclear Information System (INIS)

Spah, Manjula; Spah, Dal Chand; Deshwal, Balraj; Lee, Seungmoon; Chae, Yoon-Keun; Park, Jin Won

2009-01-01

Electromotive force (E) measurements were made on an electrochemical cell [Cu x Hg|CuCl 2 (m) in a solvent S|AgCl-Ag] (where S is a dilute aqueous solution (0.01 m) of amino acid (glycine, alanine, methionine and glutamic acid) or aliphatic carboxylic acid (formic acid, acetic acid, n-butyric acid and glutaric acid)) at 30 deg. C. These measured E values were used to compute the dissociation constants (K 1 and K 2 ) and the degree of dissociation (α 1 and α 2 ) by iterative procedures. The standard cell potential (E o ) and the mean activity coefficient (γ ± ) of CuCl 2 were also determined. The E o data were next used to evaluate the Gibbs energy of transfer (ΔG tr 0 ) of CuCl 2 from water to dilute aqueous solutions of the amino/carboxylic acids. The negative ΔG tr 0 values suggested that these acids act as potential corrosion inhibitors. The magnitudes of ΔG tr 0 values show that the amino acids act as better corrosion inhibitors towards copper than the aliphatic carboxylic acids.

Absorption and emission behaviour of trans- p-coumaric acid in aqueous solutions and some organic solvents

Science.gov (United States)

Putschögl, M.; Zirak, P.; Penzkofer, A.

2008-01-01

The absorption and fluorescence behaviour of trans- p-coumaric acid ( trans-4-hydroxycinnamic acid) is investigated in buffered aqueous solution over a wide range from pH 1 to pH 12, in un-buffered water, and in some organic solvents. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and degrees of fluorescence polarisation are measured. p-Coumaric acid exists in different ionic forms in aqueous solution depending on the pH. There is an equilibrium between the neutral form ( p-CAH 2) and the single anionic form ( p-CAH -) at low pH (p Kna ≈ 4.9), and between the single anionic and the double anionic form ( p-CA 2-) at high pH (p Kaa ≈ 9.35). In the organic solvents studied trans- p-coumaric acid is dissolved in its neutral form. The fluorescence quantum yield of trans- p-coumaric acid in aqueous solution is ϕF ≈ 1.4 × 10 -4 for the neutral and the single anionic form, while it is ϕF ≈ 1.3 × 10 -3 for the double anionic form. For trans- p-coumaric acid in organic solvents fluorescence quantum yields in the range from 4.8 × 10 -5 (acetonitrile) to 1.5 × 10 -4 (glycerol) were measured. The fluorescence spectra are 7700-10,000 cm -1 Stokes shifted in aqueous solution, and 5400-8200 cm -1 Stokes shifted in the studied organic solvents. Decay paths responsible for the low fluorescence quantum yields are discussed (photo-isomerisation and internal conversion for p-CA 2-, solvent-assisted intra-molecular charge-transfer or ππ ∗ to nπ ∗ transfer and internal conversion for p-CAH 2 and p-CAH -). The solvent dependence of the first ππ ∗ electronic transition frequency and of the fluorescence Stokes shift of p-CAH 2 is discussed in terms of polar solute-solvent interaction effects. Thereby the ground-state and excite-state molecular dipole moments are extracted.

Absorption and emission behaviour of trans-p-coumaric acid in aqueous solutions and some organic solvents

International Nuclear Information System (INIS)

Putschoegl, M.; Zirak, P.; Penzkofer, A.

2008-01-01

The absorption and fluorescence behaviour of trans-p-coumaric acid (trans-4-hydroxycinnamic acid) is investigated in buffered aqueous solution over a wide range from pH 1 to pH 12, in un-buffered water, and in some organic solvents. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and degrees of fluorescence polarisation are measured. p-Coumaric acid exists in different ionic forms in aqueous solution depending on the pH. There is an equilibrium between the neutral form (p-CAH 2 ) and the single anionic form (p-CAH - ) at low pH (pK na ∼ 4.9), and between the single anionic and the double anionic form (p-CA 2- ) at high pH (pK aa ∼ 9.35). In the organic solvents studied trans-p-coumaric acid is dissolved in its neutral form. The fluorescence quantum yield of trans-p-coumaric acid in aqueous solution is φ F ∼ 1.4 x 10 -4 for the neutral and the single anionic form, while it is φ F ∼ 1.3 x 10 -3 for the double anionic form. For trans-p-coumaric acid in organic solvents fluorescence quantum yields in the range from 4.8 x 10 -5 (acetonitrile) to 1.5 x 10 -4 (glycerol) were measured. The fluorescence spectra are 7700-10,000 cm -1 Stokes shifted in aqueous solution, and 5400-8200 cm -1 Stokes shifted in the studied organic solvents. Decay paths responsible for the low fluorescence quantum yields are discussed (photo-isomerisation and internal conversion for p-CA 2- , solvent-assisted intra-molecular charge-transfer or ππ* to nπ* transfer and internal conversion for p-CAH 2 and p-CAH - ). The solvent dependence of the first ππ* electronic transition frequency and of the fluorescence Stokes shift of p-CAH 2 is discussed in terms of polar solute-solvent interaction effects. Thereby the ground-state and excite-state molecular dipole moments are extracted

Suzuki-Miyaura cross-coupling reactions in aqueous media: Green and sustainable syntheses of biaryls

KAUST Repository

Polshettiwar, Vivek

2010-02-28

Carbon-carbon cross-coupling reactions are among the most important processes in organic chemistry, and Suzuki-Miyaura reactions are among the most widely used protocols for the formation of carbon-carbon bonds. These reactions are generally catalyzed by soluble palladium complexes with various ligands. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance. This Review will summarize various recently developed significant methods by which the Suzuki-Miyaura coupling was conducted in aqueous media, and analyzes if they are "real green" protocols. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

On hydrazine oxidation in nitric acid media

International Nuclear Information System (INIS)

Zil'berman, B.Ya.; Lelyuk, G.A.; Mashkin, A.N.; Yasnovitskaya, A.L.

1988-01-01

Yield of products of radiolytic ( 60 Co gamma radiation) and chemical hydrazine (HZ) oxidation in nitric acid media is studied. Under radiolyte HZ oxidation by nitric acid hydrazoic acid, ammonia and nitrogen appear to be the reaction products. HN 3 yield maximum under HZN oxidation makes up ∼ 0.35 mol per a mol of oxiduzed HZN. Under chemical oxidation HZN is oxidized by HNO 3 according to reaction catalysed by technetium HN 3 yield makes up ∼ 0.35 mol per a mol of oxidized HZN. Radiation-chemical oxidation of HN 3 proceeds up to its complete decomposition, decomposition rate is comparable with HZ oxidation rate. Under the chemical oxidation HN 3 is more stable, it is slowly decomposed after complete HZ decomposition

Aqueous Extracts of Hibiscus sabdariffa Calyces to Control Aichi Virus.

Science.gov (United States)

D'Souza, Doris H; Dice, Lezlee; Davidson, P Michael

2016-06-01

Aqueous Hibiscus sabdariffa extracts possess antimicrobial properties with limited information available on their antiviral effects. Aichi virus (AiV) is an emerging foodborne pathogen that causes gastroenteritis. Vaccines are currently unavailable to prevent their disease transmission. The objective of this study was to determine the antiviral effects of aqueous H. sabdariffa extracts against AiV. AiV at ~5 log PFU/ml was incubated with undiluted (200 mg/ml), 1:1 (100 mg/ml) or 1:5 (40 mg/ml) diluted aqueous hibiscus extract (pH 3.6), phosphate-buffered saline (pH 7.2 as control), or malic acid (pH 3.0, acid control) at 37 °C over 24 h. Treatments were stopped by serially diluting in cell-culture media containing fetal bovine serum and titers were determined using plaque assays on confluent Vero cells. Each treatment was replicated thrice and assayed in duplicate. AiV did not show any significant reduction with 1:1 (100 mg/ml) or 1:5 (40 mg/ml) diluted aqueous hibiscus extracts or malic acid after 0.5, 1, or 2 h at 37 °C. However, AiV titers were reduced to non-detectable levels after 24 h with all the three tested concentrations, while malic acid showed only 0.93 log PFU/ml reduction after 24 h. AiV was reduced by 0.5 and 0.9 log PFU/ml with undiluted extracts (200 mg/ml) after 2 and 6 h, respectively. AiV treated with 1:1 (100 mg/ml) and 1:5 (40 mg/ml) diluted extracts showed a minimal ~0.3 log PFU/ml reduction after 6 h. These extracts show promise to reduce AiV titers mainly through alteration of virus structure, though higher concentrations may have improved effects.

Mixed system of ionic liquid and non-ionic surfactants in aqueous media: Surface and thermodynamic properties

International Nuclear Information System (INIS)

Bhatt, Darshak; Maheria, Kalpana; Parikh, Jigisha

2014-01-01

Highlights: • Interaction of ionic liquid and ethylene oxide based non-ionic surfactants in aqueous media. • Evaluation of various surface properties and thermodynamic parameters. • Micellar growth ensues from exothermic to endothermic with increase in temperature. • Micelle formation is enthalpy driven at low temperature and entropy driven at higher temperature. • The micellization power and adsorption proficiency decreased at high IL concentrations. - Abstract: The mixed system of ionic liquid (IL) tetraethyl ammonium tetrafluoroborate [TEA(BF 4 )] and numerous ethylene oxide based non-ionic surfactants in aqueous media were studied using surface tension, viscosity and dynamic light scattering (DLS) measurements. Various surface properties like critical micelle concentration (cmc), maximum surface excess concentration (Γ max ), minimum surface area per surfactant molecule (A min ), surface tension at the cmc (γ cmc ), adsorption efficiency (pC 20 ), and effectiveness of surface tension reduction (π cmc ) as well as thermodynamic parameters of micellization have been determined. DLS and viscosity measurements revealed that the micellar growth was attributed to the bridged solvophilicity of the POE chain in surfactants at elevated temperatures. In most of the cases, the progression ensues from exothermic to endothermic with increase in temperature of the mixed system. Thermodynamic parameter indicates that the micelle formation process is enthalpy driven at low temperature and entropy driven at higher temperature

Oxidation of ascorbic acid by a (salen)ruthenium(VI) nitrido complex in aqueous solution.

Science.gov (United States)

Wang, Qian; Man, Wai-Lun; Lam, William W Y; Lau, Tai-Chu

2014-12-25

The oxidation of ascorbic acid (H2A) by [Ru(VI)(N)(L)(MeOH)](+) in aqueous acidic solutions has the following stoichiometry: 2[Ru(VI)(N)] + 3H2A → 2[Ru(III)(NH2-HA)](+) + A. Mechanisms involving HAT/N-rebound at low pH (≤2) and nucleophilic attack at the nitride at high pH (≥5) are proposed.

Adsorption of tannic acid from aqueous solution onto surfactant-modified zeolite

Energy Technology Data Exchange (ETDEWEB)

Lin, Jianwei, E-mail: jwlin@shou.edu.cn [College of Marine Science, Shanghai Ocean University, No. 999 Hucheng Huan Road, Pudong District, Shanghai 201306 (China); Zhan, Yanhui; Zhu, Zhiliang [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Xing, Yunqing [College of Marine Science, Shanghai Ocean University, No. 999 Hucheng Huan Road, Pudong District, Shanghai 201306 (China)

2011-10-15

Graphical abstract: Surfactant-modified zeolites (SMZs) with various loadings of cetylpyridinium bromide (CPB) were used as adsorbents to remove tannic acid (TA) from aqueous solution. Highlights: {yields} Surfactant modified zeolites (SMZs) have a good tannic acid (TA) adsorption capacity. {yields} Adsorption capacity for SMZ with bilayer was relatively high at solution pH 3.5-7.0. {yields} Adsorption was well described by pseudo-second-order kinetic model. {yields} Adsorption fitted well with Langmuir, Redlich-Peterson and Sips isotherm models. {yields} Coexisting Cu(II) in aqueous solution resulted in markedly enhanced TA adsorption. - Abstract: Surfactant-modified zeolites (SMZs) with various loadings of cetylpyridinium bromide (CPB) were used as adsorbents to remove tannic acid (TA) from aqueous solution. The TA adsorption efficiencies for natural zeolite and various SMZs were compared. SMZ presented higher TA adsorption efficiency than natural zeolite, and SMZ with higher loading amount of CPB exhibited higher TA adsorption efficiency. The adsorption of TA onto SMZ as a function of contact time, initial adsorbate concentration, temperature, ionic strength, coexisting Cu(II) and solution pH was investigated. The adsorbents before and after adsorption were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR) spectroscopy. The adsorption kinetics of TA onto SMZ with CPB bilayer coverage (SMZ-CBC) followed a pseudo-second-order model. The equilibrium adsorption data of TA onto SMZ-CBC were well represented by Langmuir, Redlich-Peterson and Sips isotherm models. The calculated thermodynamic parameters indicated that TA adsorption onto SMZ-CBC was spontaneous and exothermic. The TA adsorption capacity for SMZ-CBC slightly decreased with increasing ionic strength but significantly increased with increasing Cu(II) concentration. The TA adsorption

The structure and diffusion behaviour of the neurotransmitter γ-aminobutyric acid (GABA) in neutral aqueous solutions

International Nuclear Information System (INIS)

Rodrigo, M.M.; Esteso, M.A.; Barros, M.F.; Verissimo, L.M.P.; Romero, C.M.; Suarez, A.F.; Ramos, M.L.; Valente, A.J.M.; Burrows, H.D.; Ribeiro, A.C.F.

2017-01-01

Highlights: • Diffusion coefficients and densities of binary aqueous solutions of γ-aminobutyric acid (GABA). • Dependence on both shape and size of GABA on its diffusion. • Interactions intramolecular and the solute-water interactions in these systems. - Abstract: GABA (γ-aminobutyric acid) is a non-protein amino acid with important physiological properties, and with considerable relevance to the food and pharmaceutical industries. Particular interest has focused on its role as an inhibitory neurotransmitter in the mammalian cerebral cortex. In this paper, we report density and mutual diffusion coefficients of GABA in non-buffered aqueous solutions (0.001–0.100) mol·dm −3 at 298.15 K. Under these conditions, 1 H and 13 C NMR spectroscopy and pH measurements show that it is present predominantly as a monomeric zwitterionic species. Diffusion coefficients have been computed assuming that this behaves as the binary system GABA/water. From density and intermolecular diffusion coefficients measurements, the molar volume, hydrodynamic radii, R h , diffusion coefficients at infinitesimal concentration, D 0 , activity coefficients and the thermodynamic factors, F T , have been estimated. Within experimental error, the hydrodynamic volume calculated from this is identical to the molar volume obtained from density measurements. From the NMR spectra and literature data, it is suggested that this amino acid diffuses in aqueous solution as a curved, coil-like hydrated zwitterionic entity.

Selective extraction of palladium with caffeine from acidic chloride media; Sansei enkabutsu yoeki karano kafuein ni yoru parajiumu no sentakuteki chushutsu

Energy Technology Data Exchange (ETDEWEB)

Kaikake, K.; Baba, Y. [Miyazaki University, Miyazaki (Japan). Faculty of Engineering

1999-06-10

In order to examine the possibility of caffeine as an extractant, the extraction of metal ions from acidic chloride media was studied at 298 K using the mixture solvent of chloroform and 2-ethyl-1-hexanol. Caffeine has exhibited a high selectivity for palladium (2) over base metals such as copper (2), nickel (2), and iron (3), and over precious metal such as platinum (4). The stoichiometric relation in the extraction of palladium (2) with caffeine was elucidated by examining the effects of chloride ion, hydrogen ion, and caffeine concentrations on its extractability. In addition, palladium (2) was found to be extracted selectively with caffeine from the mixture containing a 25-fold amount of platinum (4) or copper (2). The stripping of palladium (2) was performed to an extent of 80% by a single batchwise treatment with an aqueous mixture solution of hydrochloric acid and thiourea. (author)

Salt dependent stability of stearic acid Langmuir-Blodgett films exposed to aqueous electrolytes

NARCIS (Netherlands)

Kumar, Naveen; Wang, Lei; Sîretanu, Igor; Duits, Michael H.G.; Mugele, Friedrich Gunther

2013-01-01

We use contact angle goniometry, imaging ellipsometry, and atomic force microscopy to study the stability and wettability of Langmuir–Blodgett (LB) monolayers of stearic acid on silica substrates, upon drying and exposure to aqueous solutions of varying salinity. The influences of Ca2+ and Na+ ions

Extraction of sulfuric acid with TOPO

International Nuclear Information System (INIS)

Shuyun, Xue; Yonghui, Yang; Yanzhao, Yang; Sixiu, Sun; Borong, Bao

1998-01-01

A study on solvent extraction of sulfuric acid by tri-octylphosphine oxide (TOPO) in n-heptane has been made. Extraction coefficients of H 2 SO 4 as a function of H 2 SO 4 concentration in aqueous phase, and extractant concentrations in organic phase have been studied. The composition of extracted species, equilibrium constants of extraction reaction have been evaluated. These results are important for interpreting extraction equilibrium data of uranium(VI) or other metal ions with TOPO in sulfuric acid media. (author)

A pulse radiolysis study of salicylic acid and 5-sulpho-salicylic acid in aqueous solutions

International Nuclear Information System (INIS)

Kishore, Kamal; Mukherjee, T.

2006-01-01

Reactions of H, OH, e aq - and some one-electron oxidants have been studied with salicylic acid and 5-sulpho-salicylic acid in aqueous solutions. Rate constants for the reaction of e aq - with these compounds were of the order of 10 9 dm 3 mol -1 s -1 and this reaction led to the formation of reducing radicals which could transfer electron to methyl viologen. Other one-electron reductants were not able to reduce these compounds. OH radicals reacted with these compounds by addition pathway with very high rate constants (>10 10 dm 3 mol -1 s -1 ) while O - radical anions could oxidize these molecules to give phenoxyl type of radicals. Amongst the one-electron oxidants, only N 3 radicals and SO 4 - radicals could oxidize salicylic acid while 5-sulpho-salicylic acid could be oxidized only by SO 4 - radicals indicating that while one-electron reduction potential for semi-oxidized SA may be o1 for N 3 ? radical), it is more than 1.33V vs. NHE for semi-oxidized SSA species

Conversion of Aqueous Ammonia-Treated Corn Stover to Lactic Acid by Simultaneous Saccharification and Cofermentation

Science.gov (United States)

Zhu, Yongming; Lee, Y. Y.; Elander, Richard T.

Treatment of corn stover with aqueous ammonia removes most of the structural lignin, whereas retaining the majority of the carbohydrates in the solids. After treatment, both the cellulose and hemicellulose in corn stover become highly susceptible to enzymatic digestion. In this study, corn stover treated by aqueous ammonia was investigated as the substrate for lactic acid production by simultaneous saccharification and cofermentation (SSCF). A commercial cellulase (Spezyme-CP) and Lactobacillus pentosus American Type Culture Collection (ATCC) 8041 (Spanish Type Culture Collection [CECT]-4023) were used for hydrolysis and fermentation, respectively. In batch SSCF operation, the carbohydrates in the treated corn stover were converted to lactic acid with high yields, the maximum lactic acid yield reaching 92% of the stoichiometric maximum based on total fermentable carbohydrates (glucose, xylose, and arabinose). A small amount of acetic acid was also produced from pentoses through the phosphoketolase pathway. Among the major process variables for batch SSCF, enzyme loading and the amount of yeast extract were found to be the key factors affecting lactic acid production. Further tests on nutrients indicated that corn steep liquor could be substituted for yeast extract as a nitrogen source to achieve the same lactic acid yield. Fed-batch operation of the SSCF was beneficial in raising the concentration of lactic acid to a maximum value of 75.0 g/L.

A nanofiber functionalized with dithizone by co-electrospinning for lead (II) adsorption from aqueous media

International Nuclear Information System (INIS)

Deng, Jianjun; Kang, Xuejun; Chen, Liqin; Wang, Yu; Gu, Zhongze; Lu, Zuhong

2011-01-01

Highlights: ► We fabricated a composite electrospun nanofiber as a selective sorbent for lead (II) in PFSPE. ► The composite nanofiber was functionalized with the dithizone by co-electrospinning of the PS solution containing unbonded dithizone. ► The nanofiber was characterized by scanning electron microscope and IR spectra. ► We applied the nanofiber by packing in a cartridge. ► The nanofiber performed well in the absorption of lead (II) and was applied successfully in aqueous samples. - Abstract: An electrospun nanofiber was utilized as a sorbent in packed fiber solid phase extraction (PFSPE) for selective separation and preconcentration of lead (II). The nanofiber had a polystyrene (PS) backbone, which was functionalized with dithizone (DZ) by co-electrospinning of a PS solution containing DZ. The nanofiber exhibited its performance in a cartridge prepared by packing 5 mg of nanofiber. The nanofiber was characterized by a scanning electron microscope and IR spectra. The diameter of the nanofiber was less than 400 nm. After being activated by 2.0 mol L −1 NaOH aqueous solution, the nanofiber quantitatively sorbed lead (II) at pH 8.5, and the metal ion could be desorbed from it by three times of elution with a small volume of 0.1 mol L −1 HNO 3 aqueous solution. The breakthrough capacity was 16 μg mg −1 . The nanofiber could be used for concentration of lead (II) from water and other aqueous media, such as plasma with stable recovery in a simple and convenient manner.

Laser-induced photochemical reaction of aqueous maleic acid solutions containing H2O2

International Nuclear Information System (INIS)

Shimizu, Yuichi; Kawanishi, Shunichi; Suzuki, Nobutake

1995-01-01

Hydroxy acid such as glycolic, tartaric and malic acids was directly produced by XeF-laser irradiation of the N 2 -saturated maleic acid aqueous solution containing H 2 O 2 . The selectivities of these products at the maximum of tartaric acid were 71, 4, and 2% at H 2 O 2 feeding rate of 3.2 ml h -1 , respectively. On the other hand, the irradiation of maleates such as dipotassium, calcium, and disodium greatly enhanced the selectivities of tartaric acid formation to 19%, and of malic acid formation to 13%, respectively, for dipotassium maleate. It may be considered from these results that the stability of the hydroxylated intermediate radical plays an important role for the efficient formations of tartaric and malic acids. (author)

A rapid method to estimate uranium using ionic liquid as extracting agent from basic aqueous media

International Nuclear Information System (INIS)

Prabhath Ravi, K.; Sathyapriya, R.S.; Rao, D.D.; Ghosh, S.K.

2016-01-01

Room temperature ionic liquids, as their name suggests are salts with a low melting point typically less than 100 °C and exist as liquid at room temperature. The common cationic parts of ionic liquids are imidazolium, pyridinium, pyrrolidinium, quaternary ammonium, or phosphonium ions, and common anionic parts are chloride, bromide, boron tetrafluorate, phosphorous hexafluorate, triflimide etc. The physical properties of ionic liquids can be tuned by choosing appropriate cations with differing alkyl chain lengths and anions. Application of ionic liquids in organic synthesis, liquid-liquid extractions, electrochemistry, catalysis, speciation studies, nuclear reprocessing is being studied extensively in recent times. In this paper a rapid method to estimate the uranium content in aqueous media by extraction with room temperature ionic liquid tricaprylammoniumthiosalicylate ((A- 336)(TS)) followed by liquid scintillation analysis is described. Re-extraction of uranium from ionic liquid phase to aqueous phase was also studied

Dispersion of Nanomaterials in Aqueous Media: Towards Protocol Optimization.

Science.gov (United States)

Kaur, Inder; Ellis, Laura-Jayne; Romer, Isabella; Tantra, Ratna; Carriere, Marie; Allard, Soline; Mayne-L'Hermite, Martine; Minelli, Caterina; Unger, Wolfgang; Potthoff, Annegret; Rades, Steffi; Valsami-Jones, Eugenia

2017-12-25

The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and stability of the suspension. In this study, a systematic step-wise approach is carried out to identify optimal sonication conditions in order to achieve a stable dispersion. This approach has been adopted and shown to be suitable for several nanomaterials (cerium oxide, zinc oxide, and carbon nanotubes) dispersed in deionized (DI) water. However, with any change in either the nanomaterial type or dispersing medium, there needs to be optimization of the basic protocol by adjusting various factors such as sonication time, power, and sonicator type as well as temperature rise during the process. The approach records the dispersion process in detail. This is necessary to identify the time points as well as other above-mentioned conditions during the sonication process in which there may be undesirable changes, such as damage to the particle surface thus affecting surface properties. Our goal is to offer a harmonized approach that can control the quality of the final, produced dispersion. Such a guideline is instrumental in ensuring dispersion quality repeatability in the nanoscience community, particularly in the field of nanotoxicology.

Aqueous solutions of acidic ionic liquids for enhanced stability of polyoxometalate-carbon supercapacitor electrodes

Science.gov (United States)

Hu, Chenchen; Zhao, Enbo; Nitta, Naoki; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

2016-09-01

Nanocomposites based on polyoxometalates (POMs) nanoconfined in microporous carbons have been synthesized and used as electrodes for supercapacitors. The addition of the pseudocapacitance from highly reversible redox reaction of POMs to the electric double-layer capacitance of carbon lead to an increase in specific capacitance of ∼90% at 1 mV s-1. However, high solubility of POM in traditional aqueous electrolytes leads to rapid capacity fading. Here we demonstrate that the use of aqueous solutions of protic ionic liquids (P-IL) as electrolyte instead of aqueous sulfuric acid solutions offers an opportunity to significantly improve POM cycling stability. Virtually no degradation in capacitance was observed in POM-based positive electrode after 10,000 cycles in an asymmetric capacitor with P-IL aqueous electrolyte. As such, POM-based carbon composites may now present a viable solution for enhancing energy density of electrical double layer capacitors (EDLC) based on pure carbon electrodes.

A knowledge based advisory system for acid/base titrations in non-aqueous solvents

NARCIS (Netherlands)

Bos, M.; van der Linden, W.E.

1996-01-01

A computer program was developed that could advice on the choice of solvent and titrant for acid/base titrations in nonaqueous media. It is shown that the feasibility of a titration in a given solvent can be calculated from solvent properties and intrinsic acid/base properties of the sample

Thermodynamics of uranium and nitric acid extraction from aqueous solution of TBP/diluent

International Nuclear Information System (INIS)

Souza Freitas, R.F. de.

1982-06-01

A thermodynamically consistent procedure for predicting distribution equilibria for uranyl nitrate and nitric acid between an aqueous solution and 30 vol % tributyl phosphate (TBP) in a hydrocarbon diluent is studied. Experimental work is developed in order to obtain equilibrium data for the system uranyl nitrate, nitric acid, water and 30 vol % TBP in n-dodecane, at 25 0 C and 40 0 C. The theoretical equilibrium data, obtained with the aid of a computer, are compared with the experimental results. (Author) [pt

Contribution to the study of the behavior of tetravalent technetium at tracer amounts in aqueous media

International Nuclear Information System (INIS)

Guennec, J.Y.

The behavior of /sup 99m/Tc was studied first in perchloric media. Reduction of TcO 4 - by BH 4 - at pH 7 in perchloric medium leads to Tc(IV) as a radiocolloid (20 percent) and soluble TcO 2 (50 percent). Acidification of the medium oxidizes the soluble Tc(IV) fraction. Acid solutions containing only the IV species and free of radiocolloids can be studied using back extraction. Tc(IV) is extracted by the organic phases, containing or not containing TTA or HDEHP from solutions of Tc(VII) reduced by BH 4 - at pH 7. These organic phases are then contacted with aqueous phases 5 x 10 -2 to 3 M HClO 4 , and the variation of the distribution coefficient was studied as a function of the chelating agent content and of the pH. In the absence of a chelating agent, the extracted species is TcO 2 . In the presence of chelating agents, the cation TcO(OH) + is extracted in the forms TcO(OH)A and TcO(OH)A 2 H respectively with TTA and HDEHP. Hydrolysis of this cation leads to TcO 2 . Study of the reduction of Tc(VII) in hydrochloric medium is complicated by the oxychlorinated forms of Tc(IV). The hexachlorotechnetate ion, TcCl 6 , exists in HCl 12 M down to 1 M and is very inert. Addition of chloride ions to solutions containing only TcO 2 and TcO(OH) + , when [Cl - ] is less than 1 M, leads to a neutral extractable species, which could be TcOCl 2 . When the Cl - concentration is greater than 1 M, there is formation of a species with one more chlorine atoms; this could be TcOCl 3 . The behavior of technetium during the formation of the complex ''Tc-Iron-Ascorbic Acid'' used in medical scintigraphy was also studied. Ascorbic acid alone or divalent iron alone slightly reduce the pertechnetate. Addition of Fe 2+ (or BH 4 - ) to Tc(VII) and ascorbic acid produces a high percentage of Tc(IV). So it is the ascorbate of iron which reduces the Tc(VII) and the excess ascorbic acid maintains the technetium in its reduced state by formation of a weak complex

A comparison of aggregation behavior in aqueous humic acids

Directory of Open Access Journals (Sweden)

von Wandruszka Ray

2001-02-01

Full Text Available The ability of six humic acids (HAs to form pseudomicellar structures in aqueous solution was evaluated by five techniques: size exclusion chromatography; pyrene fluorescence enhancement; the pyrene I1/I3 ratio; the cloud point of dilute HA solutions; and the fluorescence anisotropy of HAs. Soil HAs were found to aggregate most easily, both on microscopic and macroscopic scales. The formation of amphiphilic structures was chiefly related to HA-solvent interactions: highly solvated HAs aggregated poorly, while a lignite derived material underwent intermolecular, rather than intramolecular, rearrangements. A newly discovered algal HA was found to have minimal aggregative properties.

Spectrographic study of neodymium complexing with hydroxyethylidenediphosphonic acid in acid media

International Nuclear Information System (INIS)

Afonin, E.G.; Pechurova, N.I.; Martynenko, L.I.

1987-01-01

High resolution spectrography is used to study neodymium (3) complexing with hydroxyethylidenediphosphonic acid (H 4 X) in aqueous solution with hydrogen ion concentration being 0.35-4.5 g-ion/l. It is shown that complex of NdH 2 X + composition characterized by λ=4290 A absorption band in electron spectrum in transition range 4 I 9/2 → 2 P 1/2 is formed in a system. The lgK stab =5.62 ± 0.07 value is calculated. It is supposed that high stability of a complex is conditioned by participation of ligand nondissociated alcohol group in coordination

Radiolytic degradation of gallic acid and its derivatives in aqueous solution

International Nuclear Information System (INIS)

Melo, R.; Leal, J.P.; Takacs, E.; Wojnarovits, L.

2009-01-01

Polyphenols, like gallic acid (GA) released in the environment in larger amount, by inducing some unwanted oxidations, may constitute environmental hazard: their concentration in wastewater should be controlled. Radiolytic degradation of GA was investigated by pulse radiolysis and final product techniques in dilute aqueous solution. Subsidiary measurements were made with 3,4,5-trimethoxybenzoic acid (TMBA) and 3,4,5-trihydroxy methylbenzoate (MGA). The hydroxyl radical and hydrogen atom intermediates of water radiolysis react with the solute molecules yielding cyclohexadienyl radicals. The radicals formed in GA and MGA solutions in acid/base catalyzed water elimination decay to phenoxyl radicals. This reaction is not observed in TMBA solution. The hydrated electron intermediate of water decomposition adds to the carbonyl oxygen, the anion thus formed protonates on the ring forming cyclohexadienyl radical or on the carbonyl group forming carbonyl centred radical. The GA intermediates formed during reaction with primary water radicals in presence of oxygen transform to non-aromatic molecules, e.g., to aliphatic carboxylic acids.

Radiolytic degradation of gallic acid and its derivatives in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Melo, R. [Instituto Tecnologico e Nuclear, UCQR, Estrada Nacional No. 10, Apartado 21, 2686-953, Sacavem (Portugal); Leal, J.P. [Instituto Tecnologico e Nuclear, UCQR, Estrada Nacional No. 10, Apartado 21, 2686-953, Sacavem (Portugal); Centro Quimica e Bioquimica, Faculdade de Ciencias da Universidade de Lisboa, 1749-016 Lisboa (Portugal); Takacs, E., E-mail: takacs@iki.kfki.hu [Institute of Isotopes, Hungarian Academy of Sciences, P.O. Box 77, H-1525 Budapest (Hungary); Wojnarovits, L. [Institute of Isotopes, Hungarian Academy of Sciences, P.O. Box 77, H-1525 Budapest (Hungary)

2009-12-30

Polyphenols, like gallic acid (GA) released in the environment in larger amount, by inducing some unwanted oxidations, may constitute environmental hazard: their concentration in wastewater should be controlled. Radiolytic degradation of GA was investigated by pulse radiolysis and final product techniques in dilute aqueous solution. Subsidiary measurements were made with 3,4,5-trimethoxybenzoic acid (TMBA) and 3,4,5-trihydroxy methylbenzoate (MGA). The hydroxyl radical and hydrogen atom intermediates of water radiolysis react with the solute molecules yielding cyclohexadienyl radicals. The radicals formed in GA and MGA solutions in acid/base catalyzed water elimination decay to phenoxyl radicals. This reaction is not observed in TMBA solution. The hydrated electron intermediate of water decomposition adds to the carbonyl oxygen, the anion thus formed protonates on the ring forming cyclohexadienyl radical or on the carbonyl group forming carbonyl centred radical. The GA intermediates formed during reaction with primary water radicals in presence of oxygen transform to non-aromatic molecules, e.g., to aliphatic carboxylic acids.

Thermal MEMS actuator operation in aqueous media/seawater: Performance enhancement through atomic layer deposition post processing of PolyMUMPs devices

Energy Technology Data Exchange (ETDEWEB)

Warnat, Stephan, E-mail: stephan.warnat@dal.ca; Forbrigger, Cameron; Hubbard, Ted [Mechanical Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4 (Canada); Bertuch, Adam; Sundaram, Ganesh [Ultratech Inc., Waltham, Massachusetts 02453 (United States)

2015-01-15

A method to enhance thermal microelectromechanical systems (MEMS) actuators in aqueous media by using dielectric encapsulation layers is presented. Aqueous media reduces the available mechanical energy of the thermal actuator through an electrical short between actuator structures. Al{sub 2}O{sub 3} and TiO{sub 2} laminates with various thicknesses were deposited on packaged PolyMUMPs devices to electrically separate the actuator from the aqueous media. Atomic layer deposition was used to form an encapsulation layer around released MEMS structures and the package. The enhancement was assessed by the increase of the elastic energy, which is proportional to the mechanical stiffness of the actuator and the displacement squared. The mechanical stiffness of the encapsulated actuators compared with the noncoated actuators was increased by factors ranging from 1.45 (for 45 nm Al{sub 2}O{sub 3} + 20 nm TiO{sub 2}) to 1.87 (for 90 nm Al{sub 2}O{sub 3} + 40 nm TiO{sub 2}). Displacement measurements were made for all laminate combinations in filtered tap water and seawater by using FFT based displacement measurement technique with a repeatability of ∼10 nm. For all laminate structures, the elastic energy increased and enhanced the actuator performance: In seawater, the mechanical output energy increased by factors ranging from 5 (for 90 nm Al{sub 2}O{sub 3}) to 11 (for 90 nm Al{sub 2}O{sub 3} + 40 nm TiO{sub 2}). The authors also measured the long-term actuator stability/reliability in seawater. Samples were stored for 29 days in seawater and tested for 17 days in seawater. Laminates with TiO{sub 2} layers allowed constant operation over the entire measurement period.

Regularities in the association of polymethacrylic acid with benzethonium chloride in aqueous solutions

Science.gov (United States)

Tugay, A. V.; Zakordonskiy, V. P.

2006-06-01

The association of cationogenic benzethonium chloride with polymethacrylic acid in aqueous solutions was studied by nephelometry, conductometry, tensiometry, viscometry, and pH-metry. The critical concentrations of aggregation and polymer saturation with the surface-active substance were determined. A model describing processes in such systems step by step was suggested.

Synthesis of high intrinsic loss power aqueous ferrofluids of iron oxide nanoparticles by citric acid-assisted hydrothermal-reduction route

International Nuclear Information System (INIS)

Behdadfar, Behshid; Kermanpur, Ahmad; Sadeghi-Aliabadi, Hojjat; Morales, Maria del Puerto; Mozaffari, Morteza

2012-01-01

Monodispersed aqueous ferrofluids of iron oxide nanoparticle were synthesized by hydrothermal-reduction route. They were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and dynamic light scattering. The results showed that certain concentrations of citric acid (CA) are required to obtain only magnetic iron oxides with mean particle sizes around 8 nm. CA acts as a modulator and reducing agent in iron oxide formation which controls nanoparticle size. The XRD, magnetic and heating measurements showed that the temperature and time of hydrothermal reaction can affect the magnetic properties of obtained ferrofluids. The synthesized ferrofluids were stable at pH 7. Their mean hydrodynamic size was around 80 nm with polydispersity index (PDI) of 0.158. The calculated intrinsic loss power (ILP) was 9.4 nHm 2 /kg. So this clean and cheap route is an efficient way to synthesize high ILP aqueous ferrofluids applicable in magnetic hyperthermia. - Graphical abstract: Monodispersed aqueous ferrofluids of iron oxide nanoparticles were synthesized by hydrothermal-reduction method with citric acid as reductant which is an efficient way to synthesize aqueous ferrofluids applicable in magnetic hyperthermia. Highlights: ► Aqueous iron oxide ferrofluids were synthesized by hydrothermal-reduction route. ► Citric acid acted as reducing agent and surfactant in the route. ► This is a facile, low energy and environmental friendly route. ► The aqueous iron oxide ferrofluids were monodispersed and stable at pH of 7. ► The calculated intrinsic loss power of the synthesized ferrofluids was very high.

Absorption and emission behaviour of trans-p-coumaric acid in aqueous solutions and some organic solvents

Energy Technology Data Exchange (ETDEWEB)

Putschoegl, M.; Zirak, P. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de

2008-01-22

The absorption and fluorescence behaviour of trans-p-coumaric acid (trans-4-hydroxycinnamic acid) is investigated in buffered aqueous solution over a wide range from pH 1 to pH 12, in un-buffered water, and in some organic solvents. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and degrees of fluorescence polarisation are measured. p-Coumaric acid exists in different ionic forms in aqueous solution depending on the pH. There is an equilibrium between the neutral form (p-CAH{sub 2}) and the single anionic form (p-CAH{sup -}) at low pH (pK{sub na} {approx} 4.9), and between the single anionic and the double anionic form (p-CA{sup 2-}) at high pH (pK{sub aa} {approx} 9.35). In the organic solvents studied trans-p-coumaric acid is dissolved in its neutral form. The fluorescence quantum yield of trans-p-coumaric acid in aqueous solution is {phi}{sub F} {approx} 1.4 x 10{sup -4} for the neutral and the single anionic form, while it is {phi}{sub F} {approx} 1.3 x 10{sup -3} for the double anionic form. For trans-p-coumaric acid in organic solvents fluorescence quantum yields in the range from 4.8 x 10{sup -5} (acetonitrile) to 1.5 x 10{sup -4} (glycerol) were measured. The fluorescence spectra are 7700-10,000 cm{sup -1} Stokes shifted in aqueous solution, and 5400-8200 cm{sup -1} Stokes shifted in the studied organic solvents. Decay paths responsible for the low fluorescence quantum yields are discussed (photo-isomerisation and internal conversion for p-CA{sup 2-}, solvent-assisted intra-molecular charge-transfer or {pi}{pi}* to n{pi}* transfer and internal conversion for p-CAH{sub 2} and p-CAH{sup -}). The solvent dependence of the first {pi}{pi}* electronic transition frequency and of the fluorescence Stokes shift of p-CAH{sub 2} is discussed in terms of polar solute-solvent interaction effects. Thereby the ground-state and excite-state molecular dipole moments are extracted.

Polarografic study about the complex formation between indium (III) and sodium azide, in aqueous media

International Nuclear Information System (INIS)

Tokoro, R.; Bertotti, M.

1988-01-01

The present work is a branch of the main work concerned with the complex formation between several metal cations and azide ligand in aqueous media. The polarographic behavior of indium in azide system showed the tendency of complexation. Using polarographic method to determine the half potential of indium at each analytical concentration afforded experimental data to evaluate the constants. The azide concentrations was modified from 1 m to 100 m , the ionic strength held at 2,0 M with sodium perchlorate, indium concentration 7.892 x 10 -4 M, and temperature kept constant at 25,0 0 C. (author) [pt

Surface Engineering of PAMAM-SDB Chelating Resin with Diglycolamic Acid (DGA) Functional Group for Efficient Sorption of U(VI) and Th(IV) from Aqueous Medium

Energy Technology Data Exchange (ETDEWEB)

Ilaiyaraja, P.; Venkatraman, B., E-mail: chemila07@gmail.com [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Deb, A.K. Singha [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India); Ponraju, D. [Safety Engineering Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Ali, Sk. Musharaf [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

2017-04-15

Highlights: • A new DGA-PAMAM-SDB chelating resin has been synthesized for actinide sorption. • Maximum sorption capacities of resin are 682 and 544.2 mg g{sup −1}for U(VI) and Th(IV). • DGA-PAMAM-SDB chelating resin could be regenerated and reused. • DFT calculation of actinides interaction with resin corroborates the experimental. • Resin is effective for sorption of actinides from both aqueous and HNO{sub 3} medium. - Abstract: A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH > 4) and nitric acid media (> 3 M). The sorption equilibrium could be reached within 60 min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG{sub 5}-SDB was estimated to be about 682 and 544.2 mg g{sup −1} respectively at 25 °C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings.

Tritium distribution ratios between the 30 % tributyl phosphate(TBP)-normal dodecane(nDD) organic phase and uranyl nitrate-nitric acid aqueous phase

International Nuclear Information System (INIS)

Fujine, Sachio; Uchiyama, Gunzou; Sugikawa, Susumu; Maeda, Mitsuru; Tsujino, Takeshi.

1989-10-01

Tritium distribution ratios between the organic and aqueous phases were measured for the system of 30 % tributyl phosphate(TBP)-normal dodecane(nDD)/uranyl nitrate-nitric acid water. It was confirmed that tritium is extracted by TBP into the organic phase in both chemical forms of tritiated water (HTO) and tritiated nitric acid (TNO 3 ). The value of tritium distribution ratio ranged from 0.002 to 0.005 for the conditions of 0-6 mol/L nitric acid, 0.5-800 mCi/L tritium in aqueous phase, and 0-125 g-U/L uranium in organic phase. Isotopic distribution coefficient of tritium between the organic and aqueous phases was observed to be about 0.95. (author)

The photochemistry of neptunium in aqueous perchloric acid solutions

International Nuclear Information System (INIS)

Friedman, H.A.; Toth, L.M.; Osborne, M.M.

1979-01-01

The photochemistry of neptunium ions in aqueous perchloric acid has been investigated using 254 and 300 nm UV radiation. In the absence of other reagents, Np(IV) and (V) oxidized to Np(VI), in a stepwise fashion, with individual quantum efficiencies for each step that vary from 0.02 to 0.004. Decreasing acid concentration favors the Np(IV) → Np(V) reaction whereas it hinders the Np(V) → Np(VI) photo-oxidation. When ethanol, acetaldehyde and other mild reducing agents are added to neptunium-perchloric acid solutions which are then photolyzed, the Np species are reduced to Np(III) in a stepwise fashion with individual quantum efficiencies that vary from 0.07 to 0.006. The overall photoredox reactions of neptunium are subject to competing secondary product reactions that become significant as the photolysis products accumulate. Absorption spectrophotometry was used to monitor the changes in Np oxidation states and reference spectra of the various Np oxidation states are given for 1.0 N HClO 4 . The Np species have absorption bands in the 300 to 1320 nm region that obey Beer's law only when they were properly resolved. (author)

Optical reading of contaminants in aqueous media based on gold nanoparticles.

Science.gov (United States)

Du, Jianjun; Zhu, Bowen; Peng, Xiaojun; Chen, Xiaodong

2014-09-10

With increasing trends of global population growth, urbanization, pollution over-exploitation, and climate change, the safe water supply has become a global issue and is threatening our society in terms of sustainable development. Therefore, there is a growing need for a water-monitoring platform with the capability of rapidness, specificity, low-cost, and robustness. This review summarizes the recent developments in the design and application of gold nanoparticles (AuNPs) based optical assays to detect contaminants in aqueous media with a high performance. First, a brief discussion on the correlation between the optical reading strategy and the optical properties of AuNPs is presented. Then, we summarize the principle behind AuNP-based optical assays to detect different contaminants, such as toxic metal ion, anion, and pesticides, according to different optical reading strategies: colorimetry, scattering, and fluorescence. Finally, the comparison of these assays and the outlook of AuNP-based optical detection are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Miswak mediated green synthesized palladium nanoparticles as effective catalysts for the Suzuki coupling reactions in aqueous media

Directory of Open Access Journals (Sweden)

Mujeeb Khan

2017-05-01

Full Text Available Green and eco-friendly synthesis of palladium nanoparticles NPs is carried out under facile and eco-friendly conditions using an aqueous solution of Salvadora persica L. (SP root extract (RE as a bioreductant, which is commonly known as Miswak. The as-synthesized Pd NPs were characterized using various spectroscopic and microscopic techniques, including, UV–Vis spectroscopy, FT-IR spectroscopy, XRD, ICP-MS and TEM. Detailed investigations of the Pd NPs have confirmed that the polyphenolic phytomolecules present in the RE of Miswak not only act as a bioreductant by facilitating the reduction and growth of Pd NPs, but they also functionalize the surface of Pd NPs and stabilized them in various solvents. Furthermore, the catalytic activity of the green synthesized Pd NPs was also tested toward the Suzuki coupling reactions of various aryl halides in aqueous media. The as-prepared Pd NPs exhibited superior catalytic activity and reusability for the Suzuki coupling reaction in aqueous and aerobic conditions. The kinetics of the reaction studied by GC revealed that the conversion of various aryl halides to biphenyl takes place in a short time.

Fermentation of aqueous plant seed extracts by lactic acid bacteria

Energy Technology Data Exchange (ETDEWEB)

Schafner, D.W.; Beuchat, R.L.

1986-05-01

The effects of lactic acid bacterial fermentation on chemical and physical changes in aqueous extracts of cowpea (Vigna unguiculata), peanut (Arachis hypogea), soybean (Glycine max), and sorghum (Sorghum vulgare) were studied. The bacteria investigated were Lactobacillus helveticus, L. delbrueckii, L. casei, L. bulgaricus, L. acidophilus, and Streptococcus thermophilus. Organisms were inoculated individually into all of the seed extracts; L. bulgaricus and S. thermophilus were also evaluated together as inocula for fermenting the legume extracts. During fermentation, bacterial population and changes in titratable acidity, pH, viscosity, and color were measured over a 72 h period at 37 degrees C. Maximum bacterial populations, titratable acidity, pH, and viscosity varied depending upon the type of extract and bacterial strain. The maximum population of each organism was influenced by fermentable carbohydrates, which, in turn, influenced acid production and change in pH. Change in viscosity was correlated with the amount of protein and titratable acidity of products. Color was affected by pasteurization treatment and fermentation as well as the source of extract. In the extracts inoculated simultaneously with L. bulgaricus and S. thermophilus, a synergistic effect resulted in increased bacterial populations, titratable acidity, and viscosity, and decreased pH in all the legume extracts when compared to the extracts fermented with either of these organisms individually. Fermented extracts offer potential as substitutes for cultured dairy products. 24 references.

Influence of Acidity on Uranyl Nitrate Association in Aqueous Solutions: A Molecular Dynamics Simulation Study

International Nuclear Information System (INIS)

de Almeida, Valmor F.; Cui, Shengting; Khomami, Bamin; Ye, Xianggui; Smith, Rodney Bryan

2010-01-01

Uranyl ion complexation with water and nitrate is a key aspect of the uranium/plutonium extraction process. We have carried out a molecular dynamics simulation study to investigate this complexation process, including the molecular composition of the various complex species, the corresponding structure, and the equilibrium distribution of the complexes. The observed structures of the complexes suggest that in aqueous solution, uranyls are generally hydrated by 5 water molecules in the equatorial plane. When associating with nitrate ions, a water molecule is replaced by a nitrate ion, preserving the five-fold coordination and planar symmetry. Analysis of the pair correlation function between uranyl and nitrate suggests that nitrates bind to uranyl in aqueous solution mainly in a monodentate mode, although a small portion of bidentates occur. Dynamic association and dissociation between uranyls and nitrates take place in aqueous solution with a substantial amount of fluctuation in the number of various uranyl nitrate species. The average number of the uranyl mononitrate complexes shows a dependence on acid concentration consistent with equilibrium-constant analysis, namely, the concentration of [UO2NO3]+ increases with nitric acid concentration.

The Homocoupling Reaction of Aromatic Terminal Alkynes by a Highly Active Palladium(II)/AgNO₃ Cocatalyst in Aqueous Media Under Aerobic Conditions.

Science.gov (United States)

Guo, Mengping; Chen, Bo; Lv, Meiyun; Zhou, Xiuling; Wen, Yongju; Shen, Xiuli

2016-05-10

A new and efficient Pd(II)/AgNO₃-cocatalyzed homocoupling of aromatic terminal alkynes is described. Various symmetrical 1,4-disubstituted-1,3-diynes are obtained in good to excellent yields. This protocol employs a loading with relatively low palladium(II) in aqueous media under aerobic conditions.

Processes for working-up an aqueous fluosilicic acid solution

Directory of Open Access Journals (Sweden)

Alpha O. Toure

2012-11-01

Full Text Available Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6%– 7%solution with yields of about 70% – 80%by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol was more successful than precipitation by sodium chloride (EA = 7452.405 J/mol. Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry.

Potentiodynamic polarization studies of bulk amorphous alloy Zr57Cu15.4Ni12.6Al10Nb5 and Zr59Cu20Ni8Al10Ti3 in aqueous HNO3 media

International Nuclear Information System (INIS)

Sharma, Poonam; Dhawan, Anil; Jayraj, J.; Kamachi Mudali, U.

2013-01-01

The potentiodynamic polarization studies were carried out on Zr based bulk amorphous alloy Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 and Zr 59 Cu 20 Ni 8 Al 10 Ti 3 in solutions of 1 M, 6 M and 11.5 M HNO 3 aqueous media at room temperature. As received specimens of Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 (5 mm diameter rod) and Zr 59 Cu 20 Ni 8 Al 10 Ti 3 (3 mm diameter rod) were polished with SiC paper before testing them for potentiodynamic polarization studies. The amorphous nature of the specimens was checked by X-ray diffraction. The bulk amorphous alloy Zr 59 Cu 20 Ni 8 Al 10 Ti 3 shows the better corrosion resistance than Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 alloy in the aqueous HNO 3 media as the value of the corrosion current density (I corr ) for Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 alloy were found to be more than Zr 59 Cu 20 Ni 8 Al 10 Ti 3 alloy in aqueous HNO 3 media. The improved corrosion resistance of Zr 59 Cu 20 Ni 8 Al 10 Ti 3 alloy is possibly due to the presence of Ti and formation of TiO 2 during anodic oxidation. Both Zr based bulk amorphous alloys shows wider passive range at lower concentration of nitric acid and the passive region gets narrowed down with the increase in concentration. A comparison of data obtained from both the Zr-based bulk amorphous alloys is made and results are discussed in the paper. (author)

Solid Silica-based Sulphonic Acid as an Efficient Green Catalyst for ...

African Journals Online (AJOL)

NJD

Solid Silica-based Sulphonic Acid as an Efficient Green. Catalyst for the Selective Oxidation of Sulphides to. Sulphoxides using NaCIO in Aqueous Media. Ali Amoozadeh* and Firouzeh Nemati. Department of Chemistry, Faculty of Science, Semnan University, Semnan, Iran. Received 21 October 2008, revised 6 December ...

Thermodynamics of Dissolution for Crystalline Racemic Tartaric and Glutaric Acids and Isatin in KOH Aqueous Solutions at 298.15 K

Science.gov (United States)

Lytkin, A. I.; Chernikov, V. V.; Krutova, O. N.; Litvinenko, V. E.; Volkov, A. V.; Bychkova, S. A.; Skvortsov, I. A.

2018-01-01

Enthalpies of dissolution are found for crystalline racemic tartaric and glutaric acids and isatin in water and in potassium hydroxide solutions at 298.15 K via direct calorimetry. The protolytic equilibria in isatin aqueous solutions are studied at 298.15 K and ionic strengths of 0.5 (relative to potassium nitrate) by potentiometric means. Standard enthalpies of formation are calculated for racemic tartaric and glutaric acids, isatin, and the products of their dissociation in aqueous solutions.

Interaction of magnesium diboride with HΛ2O, HΛ2OΛ2 and with acids

International Nuclear Information System (INIS)

Lyashenko, V.I.; Kosolapova, T.Ya.; Serebryakova, T.I.

1985-01-01

Chemical stability of magnesium diboride in some agressive media is investigated. It is shown that magnesium diboride possesses high chemical activity in relation to acids (nitric, phosphoric, hydrochloric, sulphuric). The fluohydric acid and hydrogen peroxide completely decompose magnesium boride. The kinetics of MgB 2 decomposition in aqueous solutions of acids (hydrochloric, sulphuric, nitric) and in water is studied. Activation energies and solubility rate constants are calculated

The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Johnson, Steven [Iowa State Univ., Ames, IA (United States)

1999-02-12

The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

Second harmonic study of acid-base equilibrium at gold nanoparticle/aqueous interface

Science.gov (United States)

Ma, Jianqiang; Mandal, Sarthak; Bronsther, Corin; Gao, Zhenghan; Eisenthal, Kenneth B.

2017-09-01

Interfacial acid-base equilibrium of the capping molecules is a key factor to stabilize gold nanoparticles (AuNP) in solution. In this study we used Second Harmonic (SH) generation to measure interfacial potential and obtained a surface pKa value of 3.3 ± 0.1 for the carboxyl group in mercaptoundecanoic acid (MUA) molecule at an AuNP/aqueous interface. This pKa value is smaller than its bulk counterpart and indicates that the charged carboxylate group is favored at the AuNP surface. The SH findings are consistent with the effects of the noble metal (gold) surface on a charge in solution, as predicted by the method of images.

Rapid anion exchange separation of fermium with mineral acid-methyl alcohol mixed media

International Nuclear Information System (INIS)

Usuda, S.; Shinohara, N.; Ichikawa, S.; Suzuki, T.

1987-01-01

Anion exchange separation of 250 Fm (30 m) synthesized by the 12 C+ 242 Pu and 16 O+ 238 U reactions was investigated with mineral acid-methyl alcohol mixed media at elevated temperature. Fermium was chromatographically separated from the other transplutonium elements, the target materials and an Al catcher foil by anion exchange with mixtures of nitric acid and methyl alcohol. By use of the mixed media of hydrochloric acid and methyl alcohol, Fm together with Cf was separated from Al, Am, Cm, Pu, U and from major fission products. The separation systems are suitable for rapid separation and immediate alpha-counting source preparation of Fm. (author) 22 refs.; 4 figs

Coefficients of interphase distribution and Gibbs energy of the transfer of nicotinic acid from water into aqueous solutions of ethanol and dimethylsulfoxide

Science.gov (United States)

Grazhdan, K. V.; Gamov, G. A.; Dushina, S. V.; Sharnin, V. A.

2012-11-01

Coefficients of the interphase distribution of nicotinic acid are determined in aqueous solution systems of ethanol-hexane and DMSO-hexane at 25.0 ± 0.1°C. They are used to calculate the Gibbs energy of the transfer of nicotinic acid from water into aqueous solutions of ethanol and dimethylsulfoxide. The Gibbs energy values for the transfer of the molecular and zwitterionic forms of nicotinic acid are obtained by means of UV spectroscopy. The diametrically opposite effect of the composition of binary solvents on the transfer of the molecular and zwitterionic forms of nicotinic acid is noted.

Silica coating of luminescent quantum dots prepared in aqueous media for cellular labeling

Energy Technology Data Exchange (ETDEWEB)

Ma, Yunfei; Li, Yan, E-mail: yli@ecust.edu.cn; Zhong, Xinhua, E-mail: zhongxh@ecust.edu.cn

2014-12-15

Graphical abstract: A facile route based on modified Stöber method was used for the synthesis of silica coated QDs (QD@SiO{sub 2}) starting from aqueously prepared CdTe/CdS QDs. The resultant QD@SiO{sub 2} exhibited a significant increase in emission efficiency compared with that of the initial QDs, along with a small size (∼5 nm in diameter), great stability and low cytotoxicity, which makes it a good candidate as robust biomarker. - Highlights: • We present a facile modified Stöber method to prepare highly luminescent QD@SiO{sub 2}. • The PL efficiency of QDs increases significantly after silica coating. • QD@SiO{sub 2} exhibits small size (∼5 nm) and great dispersibility in aqueous solution. • QD@SiO{sub 2} presents extraordinary photo and colloidal stability. • The silica shell eliminates QD cytotoxicity, providing the access of bioconjugation. - Abstract: Silica coating is an effective approach for rendering luminescent quantum dots (QDs) with water dispersibility and biocompatibility. However, it is still challenging to prepare silica-coated QDs (QD@SiO{sub 2}) with high emission efficiency, small size and great stability in favor for bioapplication. Herein, we reported a modified Stöber method for silica coating of aqueously-prepared CdTe/CdS QDs. With the coexistence of Cd{sup 2+} and thioglycolic acid (TGA), a thin silica shell was formed around QDs by the hydrolysis of tetraethyl orthosilicate (TEOS). The resultant QD@SiO{sub 2} with a small size (∼5 nm in diameter) exhibits significantly higher emission efficiencies than that of the initial QDs. Also, QD@SiO{sub 2} has extraordinary photo and colloidal stability (pH range of 5–13, 4.0 M NaCl solution). Protected by the silica shell, the cytotoxicity of QDs could be reduced. Moreover, the QD@SiO{sub 2} conjugated with folic acid (FA) presents high specific binding toward receptor-positive HeLa cells over receptor-negative A549 cells.

Interactions of short chain phenylalkanoic acids within ionic surfactant micelles in aqueous media

Directory of Open Access Journals (Sweden)

Naeem Kashif

2012-01-01

Full Text Available % SDS KR nema Solubilization and interactions of phenylalkanoic acids induced by cationic surfactant, cetyltrimethylammonium bromide (CTAB and an anionic surfactant, sodium dodecyl sulfate (SDS was investigated spectrophotometrically at 25.0°C. The UV spectra of the additives (acids were measured with and without surfactant above and below critical micelle concentration (cmc of the surfactant. The presence of alkyl chain in phenylalkanoic acids is responsible for hydrophobic interaction resulting in shift of the spectra towards longer wavelength (red shift. The value of partition coefficient (Kx between the bulk water and surfactant micelles and in turn standard free energy change of solubilization (ΔGpº were also estimated by measuring the differential absorbance (ΔA of the additives in micellar solutions.

Carboxylic acid effects on the size and catalytic activity of magnetite nanoparticles.

Science.gov (United States)

Hosseini-Monfared, Hassan; Parchegani, Fatemeh; Alavi, Sohaila

2015-01-01

Magnetite nanoparticles (Fe3O4-NPs) were successfully synthesized in diethylene glycol in the presence of carboxylic acids. They were characterized using XRD, SEM and FTIR. Carboxylic acid plays a critical role in determining the morphology, particle size and size distribution of the resulting particles. The results show that as-prepared magnetite nanoparticles are monodisperse and highly crystalline. The nanoparticles can be easily dispersed in aqueous media and other polar solvents due to coated by a layer of hydrophilic polyol and carboxylic acid ligands in situ. Easily prepared Fe3O4-NPs have been shown to be an active, recyclable, and highly selective catalyst for the epoxidation of cyclic olefins with aqueous 30% H2O2. Copyright © 2014 Elsevier Inc. All rights reserved.

Adsorption of and acidic dye from aqueous solution by surfactant modified bentonite

International Nuclear Information System (INIS)

Bouberka, Z.; Khenifi, A.; Belkaid, N.; Ait Mahamed, H.; Haddou, B.; Derriche, Z.

2009-01-01

The aim of this paper is to study the adsorption of an acidic dye S. Y. 4 GL (i.e: Supranol yellow 4GL) from aqueous solution on inorgano-organo clay. Bentonite is a kind of natural clay with good exchanging ability. By exchanging its inter lamellar cations with Cetyltrimethylammonium bromide (CTAB) and hydroxy aluminic or chromium poly cations, the properties of natural bentonite can be greatly improved. (Author)

Steric structure and thermodynamic aspects of Dy3+ complexes with aminobenzoic acids in aqueous solutions

International Nuclear Information System (INIS)

Kondrashina, Yu.G.; Mustafina, A.R.; Vul'fson, S.G.

1994-01-01

Stability and structure of dysprosium(3) aminobenzoate complexes with molar ratios Dy:L 1:1 and 1:2 (HL-aminobenzoic acid) in aqueous solutions are determined on the basis of pH-metric and paramagnetic birefringence data. The increase of conjugation effect in the series of benzoic, meta- ortho-, and para-aminobenzoic acid results in the increase of stability of 1:1 and 1:2 complexes. Features of the structure and coordination of ligands in dysprosium complexes with meta-, ortho-, and para-aminobenzoic acid are considered. 11 refs.; 4 figs.; 2 tabs

Photophysics and Photochemistry of 2-Aminobenzoic Acid Anion in Aqueous Solution

Science.gov (United States)

Pozdnyakov, Ivan P.; Plyusnin, Victor F.; Grivin, Vjacheslav P.

2009-11-01

Nanosecond laser flash photolysis and absorption and fluorescence spectroscopy were used to study photochemical processes of 2-aminobenzoic acid anion (ABA-) in aqueous solutions. Excitation of this species gives rise to the ABA- triplet state to the ABA• radical and to the hydrated electron (eaq-). The last two species result from two-photon processes. In a neutral medium, the main decay channels of ABA- triplet state, the ABA• radical, and eaq- are T-T annihilation, recombination, and capture by the ABA- anion, respectively.

Suitability of peracetic acid for sterilization of media for mycoplasma cultures.

Science.gov (United States)

Wutzler, P; Sprössig, M; Peterseim, H

1975-01-01

The utility of peracetic acid for sterilization of serum and yeast extract additions to mycoplasma medium was studied by culturing six Mycoplasma species. Culture media containing additions that had been sterilized with peracetic acid proved to be as good as filtered components. The use of 0.05 to 0.1% peracetic acid is recommended to sterilize the serum and yeast extract additions since savings in time and equipment can be accomplished. PMID:1100656

Influence of additives on thermoresponsive polymers in aqueous media: a case study of poly(N-isopropylacrylamide).

Science.gov (United States)

Umapathi, Reddicherla; Reddy, P Madhusudhana; Rani, Anjeeta; Venkatesu, Pannuru

2018-04-18

Thermoresponsive polymers (TRPs) in different solvent media have been studied over a long period and are important from both scientific and technical points of view. Despite numerous studies on the behavior of TRPs with various additives, the interactions of additives with TRPs are still poorly understood. Moreover, despite the vast available literature regarding the biomolecular interactions between various TRPs and naturally occurring additives, it is not possible to provide a unifying declaration about the behavior of different additives, in particular at the phase transition temperature of the polymer. However, potential reviews that describe the behavior of additives as stimuli upon the phase transition of TRPs are also absent. A lack of sufficient knowledge regarding the responses of TRPs to additives as stimuli has hindered the expansion of the wide spectrum of applications of these polymers. Therefore, it was proposed to review the responses of TRPs in the presence of various additives in aqueous media. In-depth knowledge acquired via a literature survey has drawn our attention towards filling this gap by analyzing the interactions of TRPs with different additives. In this perspective, we have systematically examined the stability, aggregation, and phase transition behaviours of various polymers in the presence of different additives. The perspective on the influence of additives as stimuli on the behavior of TRPs in an aqueous medium will provide new reliable information about intramolecular interactions between interior polymer segments as well as intermolecular interactions between TRPs and additive molecules, which will be helpful for industrialists in the preparation of new polymeric materials for drug-delivery systems.

Amination of oxy acids in aqueous solution by gamma-irradiation

International Nuclear Information System (INIS)

Ema, Kimiko; Kato, Taizo; Shinagawa, Mutsuaki

1978-01-01

Alanin, β-alanine, glicine, and aspartic, α-amino-n-butyric, and γ-amino-n-butyric acids were obtained by γ-irradiation of aqueous ammonia solutions of lactic, β-oxypropionic, glycolic, malic, α-oxybutyric, and γ-oxybutyric acids, respectively. The yields of amino acids were examined for functions of radiation dose (0.75 - 3.55Mrad), concentrations of oxy acid (0.01 - 0.1M) and ammonia (0.1 - 15M), and substances added as radical (potassium iodide), and hydrated electron (nitrous oxide) scavengers. The maximum G-values were 0.6 for alanine in a solution of 0.1M lactic acid-4M ammonia and some nitrous oxide and 1.14 for β-alanine in a solution of 0.1M β-oxypropionic acid and 0.7M ammonia. The yield of alanine increased with increased concentrations of lactic acid and ammonia due to saturation of nitrous oxide but decreased when potassium iodide (0.03M) was added. The yield of β-alanine showed a maximum increase at ca. 0.7M ammonia and decreased when potassium iodide and nitrous oxide were added. Serine was obtained from G = 0.002 in a solution of β-oxypropionic acid and increased to G = 0.058 due to saturation of nitrous oxide. The manner of chemical amination due to radiation was studied from the above results. In general, oxy acids from which hydrogen has been abstracted by an H or OH radical react with ammonia to form amino acids. The effect of ammonia concentration on the yield of amino acids demonstrates that the NH 2 radical abstracts the α-hydrogen of lactic acid but does not react with the β-hydrogen of β-oxypropionic acid. The effect of nitrous oxide indicates that hydrated electrons interfere with alanine formation, contribute to β-alanine formation, react with the carboxyl group of lactic acids to form lactamide, and abstract the β-hydroxyl group of β-oxypropionic acids to form β-alanine. (Bell, E.)

Efficiency of application of electroactivated aqueous solution in the production of bread low acidity

Directory of Open Access Journals (Sweden)

E. I. Ponomareva

2016-01-01

Full Text Available In diseases of the gastrointestinal tract, it is recommended to refrain from food oxidation. Therefore, the inclusion in the diet of bakery products with low acidity is important in the diet for such patients. One way to reduce the acidity of bread is the use of electric aqueous solution (EAS. Studied the effect of EAS with different values of рН (7.42; 9.34; 11.12 on the properties of dough and quality of bread from wheat flour first grade. The dough is kneaded straight dough method. In the fermentation process investigated the change in effective viscosity and titratable acidity. After fermentation the dough is molded, the test workpiece is subjected to proofing and baking. In ready from deliah determined the acidity, moisture content, porosity and specific volume. It is established that all samples of the test there was a decrease of effective viscosity in the fermentation process due to the occurrence of physico-chemical processes. The maximum value of effective viscosity is characterized by the semi-finished product, obtained using EAS рН of which 11.12 (3474 PA⋅s. It is revealed that the least value of ultimate рН (1.7 deg also had a sample on EAS with a рН = 11.12. The use of catholyte fraction of HRES with the given value of рН allowed to decrease the acidity in the finished product (45.5% compared with the control in the pilot study value was 1.2 degrees, while in the control to 2.2. The research concluded that the use of electroactivated aqueous solution suitable for the production of bakery products of low acidity.

Novel self-associative and multiphase nanostructured soft carriers based on amphiphilic hyaluronic acid derivatives

DEFF Research Database (Denmark)

Eenschooten, Corinne; Vaccaro, Andrea; Delie, Florence

2012-01-01

The purpose of the present study was to investigate the physicochemical properties in aqueous media of amphiphilic hyaluronic acid (HA) derivatives obtained by reaction of HA’s hydroxyl groups with octenyl succinic anhydride (OSA). The self-associative properties of the resulting octenyl succinic...

Continuous electrochemical oxidation of biomass derived 5-(hydroxymethyl)furfural into 2,5-furandicarboxylic acid

NARCIS (Netherlands)

Latsuzbaia, R.; Bisselink, R.; Anastasopol, A.; Meer, van der H.; Heck, van R.; Yagüe, M.S.; Zijlstra, M.; Roelands, M.; Crockatt, M.; Goetheer, E.; Giling, E.

2018-01-01

Abstract: A continuous electrochemical process with integrated product separation has been developed for production of 2,5-furandicarboxylic acid (FDCA) by oxidation of 5-(hydroxymethyl)furfural (HMF) in aqueous alkaline media on non-noble Ni/NiOOH foam electrodes at ambient conditions. Initially,

Principles of interactions in non-aqueous electrolyte solutions

NARCIS (Netherlands)

Lyklema, J.

2013-01-01

In this paper a review is presented on the molecular interactions in non-aqueous media of low dielectric permittivity. Qualitative and quantitative distinctions with aqueous solutions are emphasized. The reviewed themes include dispersion forces, dissociation and association equilibria,

Degradation of 2,4,5-trichlorophenoxyacetic acid in aqueous solution by 60Co-γ irradiation

International Nuclear Information System (INIS)

Liu Yuanxia; Yu Yuan; Bao Huaying

2010-01-01

2,4,5-trichlorophenoxyacetic acid(2,4,5-T) is one kind of phenoxy-hydroxy-acid herbicides, also is one kind of Endocrine Disrupting Chemicals. The degradation of 2,4,5-T in aqueous solution by 60 Co-γ irradiation was investigated in the paper. The degradation effect of different influencing factors, such as absorbed dose and irradiation aura, was studied respectively. The degradation products were preliminarily analyzed by High Performance Liquid Chromatography, UV-Vis spectrophotometer and Ion Chromatography. The results showed that 2,4,5-T could be effectively degraded in aqueous solutions by 60 Co-γ irradiation. Meanwhile, the Chloride ion was detected in the solution, whose concentration increased with the growth of absorbed dose. It was found that although both e-aq and ·OH originated from water radiolysis could eliminate 2,4,5-T, the dechlorination effect and the degradation products were different. (authors)

Chemical dosimetry at less than 1000 rad: aqueous trimesic acid solutions

International Nuclear Information System (INIS)

Matthews, R.W.; Wilson, J.G.

1981-01-01

Aqueous solutions of trimesic acid were investigated for possible use as a chemical dosimeter. In aerated 10 -2 M sulphuric acid solution containing 10 -3 M trimesic acid, a highly fluorescent product is formed with its maximum fluorescence at 450nm when excited by 350nm light. The product has fluorescence characteristics very similar to quinine in 0.05 M sulphuric acid. The fluorescence intensity is linear with dose in the range 1-1000 rad and a precision of +-2% was obtained from a number of runs. Solutions are stable for at least several days before and after irradiation. The yield is little affected by moderate changes in trimesic acid concentration, oxygen concentration, water purity, energy of radiation and irradiation temperature. The small dependence of the yield on dose rate and the effect of measurement temperature on the fluorescence signal have been quantified. The most significant factor affecting the fluorescence signal is the hydrogen ion concentration of the solution. In aerated neutral and alkaline (pH 10) solutions, hydroxytrimesic acid (HTMA) is formed with G(HTMA) equal to 2.07 +- 0.04 and 2.21 +- 0.04, for 10 -3 M trimesate. In these solutions, G(HTMA) increases appreciably with increase in the trimesate concentration. The main fluorescent product formed in irradiated acid solutions was not identified but it was not HTMA. (author)

Urea, Uric Acid, Prolactin and fT4 Concentrations in Aqueous Humor of Keratoconus Patients.

Science.gov (United States)

Stachon, Tanja; Stachon, Axel; Hartmann, Ulrike; Seitz, Berthold; Langenbucher, Achim; Szentmáry, Nóra

2017-06-01

Keratoconus is a noninflammatory disease of the cornea associated with progressive thinning and conical shape. Metabolic alterations in the urea cycle, with changes in collagen fibril stability, oxidative stress, thyroid hormones and prolactin with regulatory effect on biosynthesis and biomechanical stability of corneal stroma, may all play a role in keratoconus etiology. Our purpose was to determine urea, uric acid, prolactin and free thyroxin (fT4) concentrations in human aqueous humor (hAH) of keratoconus and cataract patients. hAH was collected from 100 keratoconus (penetrating keratoplasty) (41.9 ± 14.9 years, 69 males) and 100 cataract patients (cataract surgery) (71.2 ± 12.4 years, 58 males). Urea, uric acid, prolactin and fT4 concentrations were measured by Siemens clinical chemistry or immunoassay system. For statistical analysis, a generalized linear model (GLM) was used. Urea concentration was 11.88 ± 3.03 mg/dl in keratoconus and 16.44 ± 6.40 mg/dl in cataract patients, uric acid 2.04 ± 0.59 mg/dl in keratoconus and 2.18 ± 0.73 mg/dl in cataract groups. Prolactin concentration was 3.18 ± 0.34 ng/ml in keratoconus and 3.33 ± 0.32 ng/ml in cataract patients, fT4 20.57 ± 4.76 pmol/l in KC and 19.06 ± 3.86 pmol/l in cataract group. Urea concentration was effected through gender (p = 0.039), age (p = 0.001) and diagnosis (p = 0.025). Uric acid concentration was not effected through any of the analyzed parameters (p > 0.056). Prolactin and fT4 concentration were effected only through diagnosis (p = 0.009 and p = 0.006). Urea and prolactin concentrations are decreased, fT4 concentration is increased in aqueous humor of keratoconus patients, and uric acid concentration remains unchanged. Urea concentration in aqueous humor is also increased in older and male patients. Therefore, metabolic disorder and hormonal balance may both have an impact on keratoconus development. Further studies are necessary to assess the specific impact.

One-Pot Synthesis of Some New Pyrido[2,3-d]pyrimidine Derivatives Catalyzed by Sodium Lauryl Sulfate in Aqueous Media

Directory of Open Access Journals (Sweden)

Sheng-Hui Li

2010-01-01

Full Text Available A series of pyrido[2,3-d]pyrimidine derivatives were synthesized by the three-component reaction of aromatic aldehyde, malononitrile and 6-amino-4-hydroxy-2-mercaptopyrimidine catalyzed by sodium lauryl sulfate (SDS in aqueous media. It was interesting that further aromatization took place automatically. This method provides several advantages such as easier work-up, milder reaction conditions and environmental friendly.

The distribution of n-caprylic acid between organic solvents and aqueous sodium sulfate solution

International Nuclear Information System (INIS)

Gloe, K.; Muehl, P.; Kholkin, A.I.; Gindin, L.M.

1981-01-01

The distribution of 14 C-labelled n-caprylic acid between n-decane, benzene, isoamyl acetate, diisopropyl ketone, isoamyl alcohol and an aqueous 0.6 molar sodium sulfate solution was studied. The distribution constants and the dimerisation constants were determined for the reactions HRsub((w)) reversible HRsub((org)) and 2 HRsub((org)) reversible (HR)sub(2(org)), respectively. Both the effect of the solvent on the acid distribution and the importance of such studies for the interpretation of liquid-liquid extraction equilibria are discussed. (author)

Aerosol Fragmentation Driven by Coupling of Acid-Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals.

Science.gov (United States)

Liu, Matthew J; Wiegel, Aaron A; Wilson, Kevin R; Houle, Frances A

2017-08-10

A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps with physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular

Fabrication of MCM-41 fibers with well-ordered hexagonal mesostructure controlled in acidic and alkaline media

International Nuclear Information System (INIS)

Jafarzadeh, A.; Sohrabnezhad, Sh.; Zanjanchi, M.A.; Arvand, M.

2016-01-01

In this paper, synthesis and characterization of two type morphologies of the MCM-41mesoporous material, nano and microfibers, were investigated by electrospinning technique. The synthesis was performed in acidic and alkaline media, separately. The MCM-41 morphologies were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray powder diffraction (XRD), and nitrogen adsorption–desorption measurement. Tetraethylorthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) were used as silica and template sources for the synthesis of MCM-41 morphologies, respectively. The SEM results showed that MCM-41 nanofibers were spun in acidic media and microfibers of MCM-41 were produced in alkaline media. The XRD study revealed a long range structural ordering of mesoporous materials. The TEM results indicated rough surfaces with uniform average diameter 200 nm for nanofibers and 2 µm for microfibers. The pore diameter and surface area of calcined MCM-41 nanofibers were 2.2 nm and 970 m 2 /g, respectively. For the MCM-41 microfibers, pore sizes of 2.7 nm and surface areas 420 m 2 /g was measured. - Graphical abstract: Electrospinning method was used for fabricating of MCM-41 microfibers from TEOS in alkaline media (top) and MCM-41 nanofibers in acidic media (bottom). - Highlights: • Synthesis of MCM-41 nanofibers and microfibers by electrospinning technique. • MCM-41 nanofibers were synthesized in acidic media. • MCM-41 manofibers spun in alkaline media. • Electrospinning was a simple method for preparing of fibers with respect to chemical method.

An Exact Method to Determine the Conductivity of Aqueous Solutions in Acid-Base Titrations

Directory of Open Access Journals (Sweden)

Norma Rodríguez-Laguna

2015-01-01

Full Text Available Several works in the literature show that it is possible to establish the analytic equations to estimate the volume V of a strong base or a strong acid (Vb and Va, resp. being added to a solution of a substance or a mix of substances during an acid-base titration, as well as the equations to estimate the first derivative of the titration plot dpH/dV, and algebraic expressions to determine the buffer β capacity with dilution βdil. This treatment allows establishing the conditions of thermodynamic equilibria for all species within a system containing a mix of species from one or from various polyacid systems. The present work shows that it is possible to determine exactly the electric conductivity of aqueous solutions for these Brønsted acid-base titrations, because the functional relation between this property and the composition of the system in equilibrium is well known; this is achieved using the equivalent conductivity λi values of each of the ions present in a given system. The model employed for the present work confirms the experimental outcomes with the H2SO4, B(OH3, CH3COOH, and H3PO4 aqueous solutions’ titration.

Study of free acidity determinations in aqueous solution; Etude des dosages d'acidite libre en solution aqueuse

Energy Technology Data Exchange (ETDEWEB)

Kergreis, A [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1966-04-01

The object of this work is the study of the principal methods which can be applied to the measurement of 'free' acidity. In the first part, we define the various types of acidity which can exist in aqueous solution; then, after having studied some hydrolysis reactions, we compare the value of the neutralisation pH of the hydrated cation and that of the precipitation of the hydroxide. In the second part we have started to study the determination of the acidity of an aqueous solution. After having rapidly considered the 'total' acidity determination, we deal with the problem of the 'free' acidity titration. We have considered in particular certain methods: extrapolation of the equivalent point, colorimetric titrations with or without a complexing agent, and finally the use of ion-exchange resins with mixed aqueous and solvent solutions. (author) [French] Le but de ce travail est l'etude des principales methodes de determination de l'acidite 'libre'. Dans une premiere partie nous avons defini les differentes sortes d'acidites pouvant exister en solution aqueuse, puis apres avoir etudie quelques reactions d'hydrolyse, nous avons compare la valeur de pH de neutralisation du cation hydrate et celle de precipitation de l'hydroxyde. Dans la seconde partie nous avons aborde l'etuce des dosages de l'acidite d'une solution aqueuse. Apres avoir envisage assez rapidement la determination de l'acidite 'totale', nous traitons du probleme du titrage de l'acidite 'libre'. Nous avons porte notre attention sur certaines methodes: extrapolation du point equivalent, titrimetrie colorimetrique avec ou sans complexant, et enfin utilisation des resines echangeuses d'ions en milieu aqueux et solvant mixte.

Field effects in graphene in an interface contact with aqueous solutions of acetic acid and potassium hydroxide

Science.gov (United States)

Butko, A. V.; Butko, V. Yu.; Lebedev, S. P.; Lebedev, A. A.; Kumzerov, Yu. A.

2017-10-01

For the creation of new promising chemical sensors, it is very important to study the influence of the interface between graphene and aqueous solutions of acids and alkalis on the transistor characteristics of graphene. Transistor structures on the basis of graphene grown by thermal decomposition of silicon carbide were created and studied. For the interface of graphene with aqueous solutions of acetic acid and potassium hydroxide in the transistor geometry, with a variation in the gate-to-source voltage, the field effect corresponding to the hole type of charge carriers in graphene was observed. It is established that an increase in the concentration of molecular ions in these solutions leads to an increase in the dependence of the resistance of the transistor on the gate voltage.

Silver nanoparticles embedded polymer sorbent for preconcentration of uranium from bio-aggressive aqueous media

International Nuclear Information System (INIS)

Das, Sadananda; Pandey, Ashok K.; Athawale, Anjali A.; Subramanian, M.; Seshagiri, T.K.; Khanna, Pawan K.; Manchanda, Vijay K.

2011-01-01

Adsorptive sorbent for bio-aggressive natural aqueous media like seawater was developed by one pot simultaneous synthesis of silver nanoparticles (Ag nps) and poly(ethylene glycol methacrylate phosphate) (PEGMP) by UV-initiator induced photo-polymerization. The photo-polymerization was carried out by irradiating N,N'-dimethylformamide (DMF) solution containing appropriate amounts of the functional monomer (ethylene glycol methacrylate phosphate), UV initiator (α,α'-dimethoxy-α-phenyl acetophenone), and Ag + ions with 365 nm UV light in a multilamps photoreactor. To increase mechanical strength, nano-composite sorbent (Ag-PEGMP) was also reinforced with thermally bonded non-woven poly(propylene) fibrous sheet. Transmission electron microscopy (TEM) of the nano-composite sorbent showed uniform distribution of spherical Ag nanoparticles with particles size ranging from 3 to 6 nm. The maximum amount of Ag 0 that could be anchored in the form of nanoparticles were 5 ± 1 and 10 ± 1 wt.% in self-supported PEGMP and poly(propylene) reinforced PEGMP matrices, respectively. Ag-PEGMP sorbent was found to be stable under ambient conditions for a period of six months. Ag-PEGMP composite sorbent did not exhibit growth at all after incubation with pre-grown Escherichia coli cells, and showed non-adherence of this bacteria to the composite. This indicated that composite sorbent has the bio-resistivity due to bacterial repulsion and bactericidal properties of Ag nanoparticles embedded in the PEGMP. Sorption of U(VI) in PEGMP and Ag-PEGMP nano-composite sorbents from well-stirred seawater was studied to explore the possibility of using it for uranium preconcentration from bio-aggressive aqueous streams. The nano-composite sorbent was used to preconcentrate U(VI) from a process aqueous waste stream.

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.

Effect of magnesium acetate on the volumetric and transport behavior of some amino acids in aqueous solutions at 298.15K

International Nuclear Information System (INIS)

Banipal, Tarlok S.; Kaur, Damanjit; Banipal, Parampaul K.

2006-01-01

Densities, ρ, and viscosities, η, of glycine, dl-α-alanine, dl-α-amino-n-butyric acid, l-leucine and l-phenylalanine in 0.5, 1.0, 1.5 and 2.0 m B of aqueous magnesium acetate solutions at 298.15K have been measured as a function of concentration of amino acids using vibrating tube-digital densimeter and Ubbelohde capillary type viscometer, respectively. The apparent molar volumes, V φ , and relative viscosities, η r , of amino acids have been derived. The partial molar volume at infinite dilution, V 2 0 , and viscosity B-coefficient obtained from these data have been used to calculate the corresponding transfer parameters, Δ t V 0 , and Δ t B, for the studied amino acids from water to aqueous magnesium acetate solutions. The activation free energies, Δμ 2 0 >, for the viscous flow of solutions have been obtained by application of the transition-state theory to the viscosity B-coefficient data. The interaction coefficients and hydration number, n H , of amino acids in aqueous solutions have also been calculated to see the effect of magnesium acetate on the hydration of amino acids. The contribution of the zwitterionic end groups (NH 3 + , COO - ) and (CH 2 ) group of the amino acids to V 2 0 , viscosity B-coefficient and Δμ 2 0 > have been calculated. These results have been rationalized in terms of the hydration of hydrophilic and hydrophobic parts of amino acids

The removal of uranium from acidic media using ion exchange and/or extraction chromatography

International Nuclear Information System (INIS)

FitzPatrick, J.R.; Schake, B.S.; Murphy, J.; Holmes, K.; West, M.H.

1996-06-01

The separation and purification of uranium from either nitric acid or hydrochloric acid media can be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-addition, waste stream polishing is associated with this effort in order to achieve more complete removal of uranium prior to recycle of the acid. Extraction chromatography has been demonstrated to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps

Organic Reactions in Aqueous Media (by Chao-Jun Li and Tak-Hang Chan)

Science.gov (United States)

Rosan, Reviewed Alan M.

2000-06-01

of the diastereoselectivity that often accompanies carbonyl attack by indium, tin, and zinc organometals (Barbier-Grignard reaction). The liberal use, on nearly every page, of clear, detailed drawings enhances the text, and substantive errors are few. Inexplicably, water is described as serving as a presumptive weak Lewis acid (pages 54-55) in the aqueous Mukaiyama reaction. Occasional slips of grammar, spelling, and syntax, including confusion over the difference between media and medium, are relatively minor. Some expressions, such as "olefinated", are unfortunate and there are several mysterious changes in font. This is not a textbook and no problems are offered. Many technical advances, some occurring since this book was published, have impacted the economic and environmental advantages of water. However, these more recent findings, involving the use of triphase aqueous-fluorous-organic systems, the discovery of living homogeneous ROMP catalysis in water, the utilization of supercritical water oxidation for toxic cleanup, and the utility of biphasic supercritical carbon dioxide-water emulsions, can be appreciated within the broad scope of reactivity described here. With the emerging wide interest, technical feasibility, and rapid innovative advances and an increasingly vast literature in this area, this book is most useful as a selected compendium rather than a definitive treatise. It is certainly suitable as a reference in a special topics or an advanced course. Rich with well-explicated examples and reactions, it is an invitingly readable and valuable survey of this fascinating area.

Superhydrophobic copper surfaces fabricated by fatty acid soaps in aqueous solution for excellent corrosion resistance

Energy Technology Data Exchange (ETDEWEB)

Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin, E-mail: songaixin@sdu.edu.cn; Hao, Jingcheng

2017-03-31

Highlights: • The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol. • The fabrication process of superhydrophobic metal surfaces greatly increases the safety in industrial manufacture in commercial scale. • The superhydrophobic copper surfaces show excellent corrosion resistance. - Abstract: A simple and safe one-step immersion method was developed to obtain the stable superhydrophobic copper surfaces with excellent corrosion resistance ability using fatty acids in water-medium instead of ethanol. An organic alkali, N,N-dimethylcyclohexylamine (DMCHA), was chosen to solve the poor solubility of fatty acids in water and the high Krafft point of carboxylate salts with inorganic counterions. The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol (more than 2 d), which is universally feasible for the fabrication of superhydrophobic metal surfaces in industry scale, thereby greatly increasing the safety in industrial manufacture.

Effect of alpha irradiation on UO2 surface reactivity in aqueous media

International Nuclear Information System (INIS)

Jegou, C.; Muzeau, B.; Broudic, V.; Poulesquen, A.; Roudil, D.; Jorion, F.; Corbel, C.

2005-01-01

The option of direct disposal of spent nuclear fuel in a deep geological formation raises the need to investigate the long-term behavior of the UO 2 matrix in aqueous media subjected to α-β-γ radiation. The β-γ emitters account for most of the activity of spent fuel at the moment it is removed from the reactor, but diminish within a millennial time frame by over three orders of magnitude to less than the long-term activity. The latter persists over much longer time periods and must therefore be taken into account over a geological disposal time scale. Leaching experiments with solution renewal were carried out on UO 2 pellets doped with alpha emitters ( 238 Pu and 239 Pu) to quantify the impact of alpha irradiation on UO 2 matrix alteration. Three batches of doped UO 2 pellets with different alpha flux levels (3.30 x 10 4 , 3.30 x 10 5 , and 3.2 x 10 6 α cm -2 s -1 ) were studied. The results obtained in aerated and deaerated media immediately after sample annealing or interim storage in air provide a better understanding of the UO 2 matrix alteration mechanisms under alpha irradiation. Interim storage in air of UO 2 pellets doped with alpha emitters results in variations of the UO 2 surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO 2 pellet batches and spent fuel. Oxygen diffusion enhanced by alpha irradiation of the extreme surface layer and/or radiolysis of the air could account for the oxidation of the surface UO 2 to UO 2+x . However, leaching experiments performed in deaerated media after annealing the samples and preleaching the surface suggest that alpha radiolysis does indeed affect the dissolution, which varies with the

Bioreversible Derivatives of Phenol. 2. Reactivity of Carbonate Esters with Fatty Acid-like Structures Towards Hydrolysis in Aqueous Solutions

Directory of Open Access Journals (Sweden)

Claus Larsen

2007-10-01

Full Text Available A series of model phenol carbonate ester prodrugs encompassing derivatives with fatty acid-like structures were synthesized and their stability as a function of pH (range 0.4 – 12.5 at 37°C in aqueous buffer solutions investigated. The hydrolysis rates in aqueous solutions differed widely, depending on the selected pro-moieties (alkyl and aryl substituents. The observed reactivity differences could be rationalized by the inductive and steric properties of the substituent groups when taking into account that the mechanism of hydrolysis may change when the type of pro-moiety is altered, e.g. n-alkyl vs. t-butyl. Hydrolysis of the phenolic carbonate ester 2-(phenoxycarbonyloxy-acetic acid was increased due to intramolecular catalysis, as compared to the derivatives synthesized from ω-hydroxy carboxylic acids with longer alkyl chains. The carbonate esters appear to be less reactive towards specific acid and base catalyzed hydrolysis than phenyl acetate. The results underline that it is unrealistic to expect that phenolic carbonate ester prodrugs can be utilized in ready to use aqueous formulations. The stability of the carbonate ester derivatives with fatty acid-like structures, expected to interact with the plasma protein human serum albumin, proved sufficient for further in vitro and in vivo evaluation of the potential of utilizing HSA binding in combination with the prodrug approach for optimization of drug pharmacokinetics.

Moessbauer studies of iron(III)-(indole-3-alkanoic acids) systems in frozen aqueous solutions

International Nuclear Information System (INIS)

Kovacs, K.; Kuzmann, E.; Homonnay, Z.; Szilagyi, P.A.; Vertes, A.; Kamnev, A.A.; Sharma, V.K.

2005-01-01

Moessbauer investigations of iron(III) salts in aqueous solutions in the presence of indole-3-alkanoic acid ligands are described. The measurements showed two parallel reactions between the ligands and ferric ions: a complex formation and a redox process. The oxidation process takes place in the ligands, and a part of Fe 3+ is reduced to Fe 2+ . (author)

Decomposition of aqueous fluorene by γ-rays and product analysis

International Nuclear Information System (INIS)

Popov, P.; Getoff, Nikola

2004-01-01

Fluorene degradation was investigated in aqueous solution, saturated with air or N 2 O as a function of the absorbed radiation dose. The observed initial degradation yields (Gi values) are 2.41 and 1.04, respectively. In addition to these series, also studies were performed in media containing: 90% air and 10% N 2 O (Gi=1.1), 50% air and 50% N 2 O (Gi=0.9) and 10% air and 90% N 2 O (Gi=0.5). In all cases, as major degradation products 9-fluorenone and 9-fluorene carboxylic acid were found in addition to a mixture of aldehydes and carboxylic acids. Their yield depends on the starting pollutant concentration, absorbed radiation dose and oxygen content in the solution. For explanation of the results, probable reaction mechanisms are given

Liquid Superlubricity of Polyethylene Glycol Aqueous Solution Achieved with Boric Acid Additive.

Science.gov (United States)

Ge, Xiangyu; Li, Jinjin; Zhang, Chenhui; Luo, Jianbin

2018-03-27

Boric acid is a weak acid and has been used as a lubrication additive because of its special structure. In this study, we report that boric acid could achieve a robust superlubricity (μ friction coefficient of approximately 0.004-0.006 could be achieved with boric acid under neutral conditions (pH of approximately 6.4), which is different from the acidic conditions leading to superlubricity. The influence of various factors, including boric acid concentration, sliding speed, applied load, PEG molecular weight, and the volume of lubricant on the superlubricity, were investigated. The results reveal that the PEG aqueous solution with the boric acid additive could achieve superlubricity under a wide range of conditions. The surface composition analysis shows that the synergy effect between boric acid and PEG provides sufficient H + ions to realize the running-in process. Moreover, a composite tribochemical film composed of silica and ammonia-containing compounds were formed on the ball surface, contributing to the superlubricity. The film thickness calculation shows that superlubricity was achieved in a mixed lubrication region, and therefore, the superlubricity state was dominated by both the composite tribochemical film formed via the tribochemical reaction on the contact surfaces and the hydrodynamic lubricating film between the contact surfaces. Such a liquid superlubricity achieved under neutral conditions is of importance for both scientific understanding and engineering applications.

Separation of glycols from dilute aqueous solutions via complexation with boronic acids

Energy Technology Data Exchange (ETDEWEB)

Randel, L.A.; King, C.J.

1991-07-01

This work examines methods of separating low molecular weight glycols from dilute aqueous solution. Extraction into conventional solvents is generally not economical, since, in the literature reviewed, distribution ratios for the two- to four-carbon glycols are all less than one. Distribution ratios can be increased, however, by incorporating into the organic phase an extracting agent that will complex with the solute of interest. The extracting agent investigated in this work is 3-nitrophenylboronic acid (NPBA). NPBA, a boric acid derivative, reversibly complexes with many glycols. The literature on complexation of borate and related compounds with glycols, including mechanistic data, measurement techniques, and applications to separation processes, provides information valuable for designing experiments with NPBA and is reviewed herein. 88 refs., 15 figs., 24 tabs.

New ceramics incorporated with industrial by-products as pore formers for sorption of toxic chromium from aqueous media

Science.gov (United States)

Domopoulou, Artemi

2015-04-01

The incorporation of secondary resources including various industrial wastes as pore-forming agents into clayey raw material mixtures for the development of tailored porous ceramic microstructures is currently of increasing interest. In the present research, sintered ceramic compacts were developed incorporated with industrial solid by-products as pore formers, and then used as new sorbents for chromium removal from aqueous media. The microstructures obtained were characterized through X-ray diffraction (XRD) analysis as well as scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). Sorption potential of chromium from synthetic solutions on the porous ceramics was studied by static adsorption experiments as a function of the pore-former percentage in the ceramic matrix as well as the initial heavy metal (chromium) concentration, solution pH and temperature. Kinetic studies were conducted and adsorption isotherms of chromium were determined using the Langmuir equation. Preliminary experimental results concerning the adsorption characteristics of chromium on the ceramic materials produced appear encouraging for their possible beneficial use as new sorbents for the removal of toxic chromium from aqueous media. Keywords: sorbents, ceramics, industrial solid by-products, pore-former, chromium. Acknowledgements: This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program ARCHIMEDES III: Investing in knowledge society through the European Social Fund.

Acid-Base Equilibria of Some N-Substituted Thiophene-2-Carboxamidoximes in Non-Aqueous Media

OpenAIRE

DÜRÜST, Nedime

2002-01-01

The protonation constants of the amino nitrogens of some N-substituted thiophene-2-carboxamidoximes have been determined in acetic acid by means of potentiometric titration with perchloric acid. pKa values of the title compounds were interpreted on the basis of structural effects due to the substituents and the main skeleton.

Formation of magnetite (Fe3O4)in aqueous media and properties of the interface magnetite/solution

International Nuclear Information System (INIS)

Regazzoni, A.E.

1984-01-01

The formation of Fe 3 O 4 particles in aqueous media and the properties of the Fe 3 O 4 /aqueous solution interface are studied. This system is of particular interest in nuclear reactor chemistry, since Fe 3 O 4 was identified as the main component of the corrosion products of nuclear power plants cooled with pressurized water, of the Atucha I and II, and Embalse type. Four methods for the synthesis of Fe 3 O 4 are described: a) controlled oxidation of Fe(OH) 2 in the presence of NaNO 3 at 25 deg C; b) controlled oxidation of Fe(OH) 2 in the presence of NaNO 3 and N 2 H 4 and at 100 deg C; c) alkalinization of a F 2+ and Fe 3+ solutions at 80 deg C; d) simultaneous oxidation and alkalinization of a Fe 2+ . The interfacial properties of Fe 3 O 4 particles suspended in aqueous solutions of indifferent electrolytes are described. These properties are essential for the activity transport associated with the corrosion products. Finally, the adsorption of H 3 BO 3 , Hsub(n)PO 4 sup(n-3) and n Co(II) in the Fe 3 O 4 /solution interface at 30 deg C. It is concluded that the adsorbed species are chemically bonded to surface metal ions. (M.E.L.) [es

Pd-catalyzed ethylene methoxycarbonylation with Brønsted acid ionic liquids as promoter and phase-separable reaction media

DEFF Research Database (Denmark)

Garcia-Suarez, Eduardo J.; Khokarale, Santosh Govind; Nguyen van Buu, Olivier

2014-01-01

Brønsted acid ionic liquids (BAILs) were prepared and applied as combined acid promoters and reaction media in Pd–phosphine catalyzed methoxycarbonylation of ethylene to produce methyl propionate. The BAILs served as alternatives to common mineral acids required for the reaction, e.g. methanesulf......Brønsted acid ionic liquids (BAILs) were prepared and applied as combined acid promoters and reaction media in Pd–phosphine catalyzed methoxycarbonylation of ethylene to produce methyl propionate. The BAILs served as alternatives to common mineral acids required for the reaction, e...

Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

International Nuclear Information System (INIS)

Cemal Oezeroglu; Niluefer Metin

2012-01-01

In this paper, the crosslinked polyester resin containing acrylic acid functional groups was used for the adsorption of uranium ions from aqueous solutions. For this purpose, the crosslinked polyester resin of unsaturated polyester in styrene monomer (Polipol 353, Poliya) and acrylic acid as weight percentage at 80 and 20%, respectively was synthesized by using methyl ethyl ketone peroxide (MEKp, Butanox M60, Azo Nobel)-cobalt octoate initiator system. The adsorption of uranium ions on the sample (0.05 g copolymer and 5 mL of U(VI) solution were mixed) of the crosslinked polyester resin functionalized with acrylic acid was carried out in a batch reactor. The effects of adsorption parameters of the contact time, temperature, pH of solution and initial uranium(VI) concentration for U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid were investigated. The adsorption data obtained from experimental results depending on the initial U(VI) concentration were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The adsorption capacity and free energy change were determined by using D-R isotherm. The obtained experimental adsorption data depending on temperature were evaluated to calculate the thermodynamic parameters of enthalpy (ΔH o ), entropy (ΔS o ) and free energy change (ΔG o ) for the U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid from aqueous solutions. The obtained adsorption data depending on contact time were analyzed by using adsorption models such as the modified Freundlich, Elovich, pseudo-first order and pseudo-second-order kinetic models. (author)

Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution.

Directory of Open Access Journals (Sweden)

Renwu Zhou

Full Text Available Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS. Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma.

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.

Pertechnetate immobilization in aqueous media with hydrogen sulfide under anaerobic and aerobic environments

International Nuclear Information System (INIS)

Liu, Y.; Jurisson, S.; Terry, J.

2007-01-01

The basic chemistry for the immobilization of pertechnetate (TcO 4 - ) by hydrogen sulfide was investigated in aqueous solution under both aerobic and anaerobic environments. Pertechnetate immobilization was acid dependent, with accelerated rates and increased immobilization yields as the acid concentration increased. Oxygen had no effect under acidic conditions. Under anaerobic alkaline conditions, the pH, and therefore the speciation of sulfide, was the determining factor on the immobilization of pertechnetate. Only 53% of the TcO 4 - was immobilized at pH 8, while the yield increased to 83% at pH 9 as HS - became the dominant sulfide species. The immobilization yield then decreased to 73% at pH 13. No reaction was observed between TcO 4 - and sulfide under aerobic alkaline conditions, indicating that oxygen suppressed this reaction. Pertechnetate immobilization was found to be first order with respect to both sulfide and pertechnetate in acidic solutions, and in alkaline solution under anaerobic conditions. The results of stoichiometry studies and product analysis under alkaline anaerobic environments indicated that Tc 2 S 7 was obtained at pH 9. EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge structure) studies suggested that the samples obtained from acidic, aerobic solution and alkaline anaerobic solution were both Tc 2 S 7 . The stability of Tc 2 S 7 is affected by O 2 with accelerated dissolution at high pH. (orig.)

Electrochemical Oxidation of Silver and Copper in Aqueous Basic Media and in Fused Hydroxide Electrolytes

Directory of Open Access Journals (Sweden)

Tejada-Rosales, E. M.

2004-04-01

Full Text Available The anodic oxidations of copper and silver electrodes in basic media are reported. Experiments were conducted both in aqueous NaOH solutions and in a flux of molten NaOH/KOH eutectic. The oxidation processes were studied by means of cyclic voltammetry and chronoamperometries and the phases obtained were systematically characterized by x-ray diffraction. The ranges of stability of each phase in the different media studied are reported. In addition to known oxides of copper or silver, a new silver oxide was isolated.

En este trabajo se describe la oxidación anódico de electrodos de plata y de cobre en medios básicos. Se han utilizado tanto medios acuosos como hidróxidos fundidos (eutéctico NaOH/KOH. Los procesos de oxidación se han estudiado mediante voltametría cíclica y cronoamperometría, y las fases resultantes han sido caracterizadas por difracción de Rayos X. Los rangos de estabilidad encontrados para cada uno dependen del medio utilizado. Además de óxidos conocidos de cobre y de plata, se ha aislado un nuevo óxido de plata.

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.

Radiation-induced nitration of organic compounds in aqueous solutions

International Nuclear Information System (INIS)

Ershov, B.G.; Gordeev, A.V.; Bykov, G.L.; Moisy, P.

2012-01-01

Radiolysis in aqueous nitrate and acetic acid solutions and nitrate/nitric acid and phenol was studied. The radiolysis of these solutes occurs with circle NO 2 radical, which is the active nitrating agent. Accumulation of nitromethane and nitrite was determined during γ-irradiation of aqueous solutions containing acetic and nitrate solutions. Irradiation of aqueous phenol-nitrate/nitric acid solutions results in the formation of 2- and 4-nitrophenols.

Radiation-induced nitration of organic compounds in aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Ershov, B.G.; Gordeev, A.V.; Bykov, G.L. [Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Inst. of Physical Chemistry and Electrochemistry; Moisy, P. [CEA, Bagnols sur Ceze (France). Nuclear Energy Div.

2012-07-01

Radiolysis in aqueous nitrate and acetic acid solutions and nitrate/nitric acid and phenol was studied. The radiolysis of these solutes occurs with {sup circle} NO{sup 2} radical, which is the active nitrating agent. Accumulation of nitromethane and nitrite was determined during {gamma}-irradiation of aqueous solutions containing acetic and nitrate solutions. Irradiation of aqueous phenol-nitrate/nitric acid solutions results in the formation of 2- and 4-nitrophenols.

Fabrication and characterization of self-doped poly(aniline-co-anthranilic acid) nanorods in bundles

International Nuclear Information System (INIS)

Han Dongxue; Song Jixia; Ding Xuefeng; Xu Xiaoyu; Niu Li

2007-01-01

Poly(aniline-co-anthranilic acid) (PANANA) nanorods in bundles was prepared successfully in an alcohol/aqueous media without assistance of any other kinds of acids. Anthranilic acid played all roles of monomer, acid-media provider, and dopant in the reaction system, and ammonium persulfate (APS) served as the oxidant. The morphologies of PANANA nanorods in bundles were investigated by scanning electron microscopy (SEM). Influences of the monomer molar ratio on the resulting morphology were investigated. Moreover the formation mechanism of the nanostructured copolymer was proposed. FT-IR, UV-vis and X-ray diffraction (XRD) measurements were used to confirm the molecular and electrical structure of the self-doped PANANA. The intrinsic properties, such as conductivity, electrochemical redox activity and room-temperature solubility of the resulting copolymer were explored

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

Polymerization of acrylamide initiated with Ce(IV- and KMnO4–mercaptosuccinic acid redox systems in acid-aqueous medium

Directory of Open Access Journals (Sweden)

2007-03-01

Full Text Available By using mercaptosuccinic acid-cerium(IV sulfate and mercaptosuccinic acid-KMnO4 redox systems in acid aqueous medium, the polymerization of acrylamide monomer was performed at room temperatures. Water soluble acrylamide polymers which contain mercaptosuccinic acid end-groups were synthesized. The dependence of polymerization yield and the molecular weight of polymer on the initiator concentration(nMSA=nCe(IV at different acid concentrations, polymerization time, temperature, and concentration of sulfuric acid was investigated. The decrease in the initiator concentration resulted in an increase in the molecular weights but a decrease in the yield. The increase of reaction temperature from 20 to 60°C resulted in an increase in the molecular weights and slight decrease of the yield of polymer. Cerium and manganese ions are reduced to Ce(III and Mn(II ions respectively in polymerization reaction. The existence of Ce(III ion bound to polymer was investigated by UV-visible spectrometry and fluorescence measurements. The amount of Mn(II which is incorporated to the polymer was determined.

Dissolution of anodic zirconium dioxide films in aqueous media

International Nuclear Information System (INIS)

Merati, A.; Cox, B.

1999-01-01

Zirconium with a low thermal neutron cross section, good corrosion resistance in high-temperature water, and high thermal conductivity is an ideal material for nuclear reactors. Its good resistance to water and steam at reactor temperatures is of the greatest interest to nuclear fuel designers. Dissolution of zirconium dioxide (ZrO 2 ) films in aggressive media was investigated. The extent of uniform and localized dissolution was measured by ultraviolet-visible (UV-VIS) spectrometry and an alternating current (AC) impedance test, respectively. Scanning electron microscopy (SEM) showed the extent of dissolution of ZrO 2 was a function only of the fluoride ion content and pH of the medium. Cathodic polarization was used to identify the preferred sites for localized dissolution of the oxide film. In 0.1 M potassium bifluoride (KHF 2 ), both uniform thinning and local breakdown of the oxide were observed. Within the limits of the investigating techniques, no evidence of dissolution was observed in the other solutions tested: 0.5 M sulfuric acid (H 2 SO 4 ). 1.0 M nitric acid (HNO 3 ), 5 M hydrochloric acid (HCl), or 0.1 M potassium fluoride (KF). In areas around iron-containing particles, fine cracks in the anodic oxide at prior metal grain boundaries and arrays of cracks in the oxide associated with residual scratches from the initial specimen preparation were the preferred spots for localized dissolution of the oxide film. Iron precipitates immediately below the surface of the oxide layer increased the local electrical conductivity. Enrichment of iron in the oxide matrix around these precipitates during the anodization process appeared to cause prospective spots, acting as anodic sites for pH formation

Investigation on molecular interaction of amino acids in aqueous disodium hydrogen phosphate solutions with reference to volumetric and compressibility measurements

International Nuclear Information System (INIS)

Kumar, Harsh; Singla, Meenu; Jindal, Rajeev

2014-01-01

Highlights: • Densities and speeds of sound of amino acids in aqueous disodium hydrogen phosphate. • Partial molar volumes and compressibility of transfer. • Positive values of transfer volume indicates interactions between ions of amino acids and TSC. • Ion–hydrophilic and hydrophilic–hydrophilic interactions are present. • Pair-wise interactions are dominant in the mixtures. -- Abstract: The interactions of amino acids glycine (Gly), L-alanine (Ala), and L-valine (Val) with disodium hydrogen phosphate (DSHP) as a function of temperature have been investigated by combination of volumetric and acoustic measurements. Densities (ρ) and speeds of sound (u) of amino acids in aqueous solutions of disodium hydrogen phosphate have been measured at T = (288.15, 293.15, 298.15, 303.15 and 308.15) K and atmospheric pressure. The apparent molar volume (V ϕ ), the partial molar volume (V ϕ 0 ) and standard partial molar volumes of transfer (ΔV ϕ 0 ) for amino acids from water to aqueous disodium hydrogen phosphate solutions have been calculated from density data. Partial molar adiabatic compressibility (κ ϕ,s ) and partial molar adiabatic compressibility of transfer (Δκ ϕ,S 0 ) have been calculated from speed of sound data. The pair (V AB , κ AB ) and triplet (V ABB , κ ABB ) interaction coefficient have been calculated from both the properties. The results have been explained based on competing patterns of interactions of co-solvents and the solute

Measurement of Solute Diffusion Behavior in Fractured Waste Glass Media

International Nuclear Information System (INIS)

Saripalli, Kanaka P.; Lindberg, Michael J.; Meyer, Philip D.

2008-01-01

Determination of aqueous phase diffusion coefficients of solutes through fractured media is essential for understanding and modeling contaminants transport at many hazardous waste disposal sites. No methods for earlier measurements are available for the characterization of diffusion in fractured glass blocks. We report here the use of time-lag diffusion experimental method to assess the diffusion behavior of three different solutes (Cs, Sr and Pentafluoro Benzoic Acid or PFBA) in fractured, immobilized low activity waste (ILAW) glass forms. A fractured media time-lag diffusion experimental apparatus that allows the measurement of diffusion coefficients has been designed and built for this purpose. Use of time-lag diffusion method, a considerably easier experimental method than the other available methods, was not previously demonstrated for measuring diffusion in any fractured media. Hydraulic conductivity, porosity and diffusion coefficients of a solute were experimentally measured in fractured glass blocks using this method for the first time. Results agree with the range of properties reported for similar rock media earlier, indicating that the time-lag experimental method can effectively characterize the diffusion coefficients of fractured ILAW glass media

Solubility behavior of narcotic analgesics in aqueous media: solubilities and dissociation constants of morphine, fentanyl, and sufentanil.

Science.gov (United States)

Roy, S D; Flynn, G L

1989-02-01

The pH dependence of the aqueous solubility of morphine, fentanyl, and sufentanil was investigated at 35 degrees C. Dissociation constants and corresponding pKa' values of the drugs were obtained from measured free-base solubilities (determined at high pH's) and the concentrations of saturated solutions at intermediate pH's. Morphine, fentanyl, and sufentanil exhibited pKa' values of 8.08, 8.99, and 8.51, respectively. Over the pH range of 5 to 12.5 the apparent solubilities are determined by the intrinsic solubility of the free base plus the concentration of ionized drug necessary to satisfy the dissociation equilibrium at a given pH. Consequently, the drug concentrations of saturated aqueous solutions fall off precipitously as the pH is raised and ionization is suppressed. Further, at low pH's the aqueous solubility of morphine increased in a linear fashion with increases in the molar strength of citric acid which was added to acidify the medium, suggesting the formation of a soluble morphine-citrate complex.

Effect of different media on production of lactic acid from whey by ...

African Journals Online (AJOL)

Whey containing 50 g.l -1 lactose was fermented to lactic acid in batch process by Lactobacillus bulgaricus. The impact of 5 different media with change in volume percent of whey and nutrient was investigated at 32 ± 0.5°C. Substrate consumption and lactic acid production were determined at 0, 12, 24, 36, 48, 60 and 72 h.

Conductimetric and Potentiometric Titration of Some Hydroxylated Cinnamic Acids with Tetrabutylammonium Hydroxide in Non-Aqueous Media

OpenAIRE

AKTAŞ, A. Hakan; YAŞAR, Gülsüm; ALSANCAK, Güleren ÖZKAN

2001-01-01

In this study, four hydroxycinnamic acids, namely 3,4-dihydroxycinnamic acid, 4-hydroxycinnamic acid, 4-hydroxy --3- methoxycinnamic acid and 4-hydroxy-3,5-dimethoxycinnamic acid, were titrated conductimetrically and potentiometrically using triethylamine and tetrabutylammonium hydroxide in acetonitrile, 2-propanol, and pyridine solvents under a nitrogen atmosphere at 25 oC. In conductimetric titration with tetrabutylammonium hydroxide all of the compounds exhibited conventional s...

Silver colloidal effects on excited-state structure and intramolecular charge transfer of p-N, N-dimethylaminobenzoic acid in aqueous cyclodextrin solutions

International Nuclear Information System (INIS)

Choi, Jung Kwon; Kim, Yang Hee; Yoon, Min Joong; Lee, Seung Joon; Kim, Kwan; Jeoung, Sae Chae

2001-01-01

The silver colloidal effects on the excited-state structure and intramolecular charge transfer (ICT) of p-N,N-dimethylaminobenzoic acid (DMABA) in aqueous cyclodextrin (CD) solutions have been investigated by UV-VIS absorption, steady-state and time-resolved fluorescence, and transient Raman spectroscopy. As the concentration of silver colloids increases, the ratio of the ICT emission to the normal emission (I a /I b ) of DMABA in the aqueous α-CD solutions are greatly decreased while the I a /I b values in the aqueous β-CD solutions are significantly enhanced. It is also noteworthy that the ICT emission maxima are red-shifted by 15-40 nm upon addition of silver colloids, implying that DMABA encapsulated in α-CD or β-CD cavity is exposed to more polar environment. The transient resonance Raman spectra of DMABA in silver colloidal solutions demonstrate that DMABA in the excited-state is desorbed from silver colloidal surfaces as demonstrated by the disappearance of v s (CO 2 - )(1380 cm -1 ) with appearance of v (C-OH)(1280 cm -1 ) band, respectively. Thus, in the aqueous β-CD solutions the carboxylic acid group of DMABA in the excited-state can be readily hydrogen bonded with the secondary hydroxyl group of β-CD while in aqueous and α-CD solutions the carboxylic acid group of DMABA has the hydrogen-bonding interaction with water. Consequently, in the aqueous β-CD solutions the enhancement of the I a /I b value arises from the intermolecular hydrogen-bonding interaction between DMABA and the secondary hydroxyl group of β-CD as well as the lower polarity of the rim of the β-CD cavity compared to bulk water. This is also supported by the increase of the association constant for DMABA/β-CD complex in the presence of silver colloids

Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

Science.gov (United States)

Blasco-Ahicart, Marta; Soriano-López, Joaquín; Carbó, Jorge J.; Poblet, Josep M.; Galan-Mascaros, J. R.

2018-01-01

Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO2 catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm-2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

Photochemical reaction between triclosan and nitrous acid in the atmospheric aqueous environment

Science.gov (United States)

Ma, Jianzhong; Zhu, Chengzhu; Lu, Jun; Lei, Yu; Wang, Jizhong; Chen, Tianhu

2017-05-01

Nitrous acid (HONO) is an important tropospheric pollutant and a major source of hydroxyl radical in the atmospheric gas phase. However, studies on the role of HONO in atmospheric aqueous phase chemistry processes are relatively few. The present work investigated the photochemical reaction of HONO with triclosan (TCS), which is an emerging contaminant, using a combination of laser flash photolysis spectrometry and gas chromatography mass spectrometry. With these techniques, the reaction pathway of HONO with TCS was proposed by directly monitoring the transient species and detecting the stable products. ·OH was generated from the photodissociation of the HONO aqueous solution and attacked TCS molecules on different sites to produce the TCS-OH adducts with a second-order rate constant of 1.11 × 109 L mol-1 s-1. The ·OH added a C atom adjacent to the ether bond in the aromatic ring of TCS and self-decayed when the ether bond broke. The intermediates generated from the addition of ·OH to the benzene ring of the TCS molecular structure were immediately nitrated by HONO, which played a key role in the formation process of nitrocompounds. An atmospheric model suggests that the aqueous oxidation of TCS by ·OH is a major reaction at high liquid water concentrations, and the photolysis of TCS dominates under low-humidity conditions.

Effect of the aqueous, acidic and alcoholic extract of dried leaves of Erythroxylum coca var. coca (coca in Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum canis and Candida albicans in vitro

Directory of Open Access Journals (Sweden)

Medalit Luna-Vílchez

2017-06-01

Full Text Available Objective: To evaluate the effect of the aqueous, acidic and alcoholic extract of dried leaves of Erythroxylum coca var. coca (coca in Trichophyton rubrum (TR, Trichophyton mentagrophytes (TM, Microsporum canis (MC and Candida albicans (CA in vitro. Materials and methods: An experimental study which evaluated the presence or absence of fungal growth, and fungal growth rate from the seeding point, compared to fungal growth in Sabouraud Agar (SA using Siegel-Tukey and KruskalWallis tests (p<0.05. Results: The CA group showed a statistical difference (p<0.05 between the following groups: 99.9% ethanol vs. aqueous, 99.9% ethanol vs. 0.01M HCl, 99.9% ethanol vs. control, control vs. aqueous, 0.01M HCl vs. control. The TR group showed a statistical difference (p<0.05 between the following groups: 99.9% ethanol vs. 0.01M HCl, 99.9% ethanol vs. aqueous, 99.9% ethanol vs. control, 0.01M HCl vs. control. The TM group showed a statistical difference (p<0.05 between the following groups: 99.9% ethanol vs. 0.01M HCl, 99.9% ethanol vs. control, aqueous vs. acid, aqueous vs. control. The MC group showed a statistical difference (p<0.05 between the following groups: 99.9% ethanol vs. 0.01M HCl, 99.9% ethanol vs. control, aqueous vs. acid, aqueous vs. control. In all the cases, the results of the 0.01M HCl vs. aqueous group were not significant. Conclusions: The aqueous, acidic and alcoholic extracts have no effect on the growth of CA and TM, but the alcoholic extract has effects on the growth of TR and MC. In addition, there were differences in the growth rate of CA, TR and TM in the aqueous, acidic and alcoholic extracts compared to that in SA. However only TR, TM and MC showed differences in their growth rate in the alcoholic extract.

Ionizing radiation induced degradation of salicylic acid in aqueous solution

Science.gov (United States)

Albarrán, Guadalupe; Mendoza, Edith

2018-06-01

The radiation-induced degradation of salicylic acid (SA-) in aqueous solutions (1.0 and 0.1 mmol dm-3) saturated with N2O or air or without oxygen were studied. Irradiation was carried out using a cobalt-60 source. With a 1 mmol dm-3 solution saturated with N2O a seemingly total degradation occurred at about 18 kGy, although small quantities of 2,3-dihydroxybenzoic acid, catechol and 2,5-dihydroxybenzoic acid were present at that dose at concentrations of 67, 22 and 6 μmol dm-3 respectively. Under air and when free oxygen, the three radiolytic products were present at 18.54 kGy while SA- was destroyed only to 90% and 62%, respectively. In the case of 0.1 mmol dm-3 SA- solutions, the acid was degraded at 3.5 kGy if the solution contained N2O, at 5.8 kGy in air and at 7 kGy without oxygen. The concentration of the radiolytic products increased with increasing dose and after a maximum they decreased. The oxidation was followed by measuring the chemical oxygen demand; the slopes were 0.48 and 0.11, 0.21 and 0.07, 0.15 and 0.03 mmol dm-3 kGy-1 for 1.0 and 0.10 mmol dm-3 solutions saturated with N2O or air or without oxygen, respectively.

The coulometric titration of acids and bases in dimethylsulfoxide media

NARCIS (Netherlands)

Bos, M.; IJpma, S.T.; Dahmen, E.A.M.F.

1976-01-01

The coulometric titration of 20–200 μeq of acids and bases in DMSO media is described. In the titration of bases, the electro-oxidation of hydrogen at a platinized platinum electrode is used as the source of protons. The conditions for 100 % current efficiency at this electrode are low current

Behavior of soluble and immobilized acid phosphatase in hydro-organic media.

Science.gov (United States)

Wan, H; Horvath, C

1975-11-20

The hydrolysis of p-nitrophenyl phosphate by wheat germ acid phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.2) has been investigated in mixtures of aqueous buffers with acetone, dioxane and acetonitrile. The enzyme was either in free solution or immobilized on a pellicular support which consisted of a porous carbonaceous layer on solid glass beads. The highest enzyme activity was obtained in acetone and acetonitrile mixed with citrate buffer over a wide range of organic solvent concentration. In 50% (v/v) acetone both V and Km of the immobilized enzyme were about half of the values in the neat aqueous buffer, but the Ki for inorganic phosphate was unchanged. In 50% (v/v) mixtures of various solvents and citrate buffers of different pH, the enzymic activity was found to depend on the pH of the aqueous buffer component rather than the pH of the hydro-organic mixture as measured with the glass-calomel electrode. The relatively high rates of p-nitrophenol liberation in the presence of glucose even at high organic solvent concentrations suggest that transphosphorylation is facilitated at low water activity.

Am and Eu extraction from acidic media by synergistic mixtures of substituted bis-tetrazolyl pyridines with chlorinated cobalt dicarbollide

International Nuclear Information System (INIS)

Smirnov, I.V.; Chirkov, A.V.; Babain, V.A.; Pokrovskaya, E.Yu.; Artamonova, T.A.

2009-01-01

Americium (Am) and europium (Eu) extraction from HNO 3 and HClO 4 media by a synergistic mixture of 2.6-bis(1-aryl-1H-tetrazol-5-yl)pyridines (ATP) with chlorinated cobalt dicarbollide (CCD) was studied by using m-nitrobenzotrifluoride, phenyltrifluoromethyl sulfone, and 1,2-dichloroethane as diluents. We examined the effects of diluents, of the aqueous phase composition and the nature of substituents in the ATP aryl ring on Am/Eu extraction efficiency and selectivity. The Am/Eu separation factor was found to be close to 100 at the optimal ratio of ATPs: CCD ∝ 1:1. We also studied the extraction of 85 Sr, 137 Cs and 133 Ba; a PhATP-CCD mixture provided the separation of the Sr/Ba pair with a factor of 35. A high resistance of 2,6-bis-aryltetrazolyl pyridines to 6 M nitric and perchloric acids at 95 C was demonstrated. (orig.)

Pulse radiolysis of adrenaline in acid aqueous solutions

International Nuclear Information System (INIS)

Gohn, M.; Getoff, N.; Bjergbakke, E.

1976-01-01

Pulse radiolysis of adrenaline in acid aqueous solutions (pH 1 to 3) was carried out. The rate constants for the reactions of adrenaline with H and 0H were determined: k(H + adr.) = (0.9 +- 0.1) x 10 9 dm 3 mol -1 s -1 ; k(0H + adr.) = (1.65 +- 0.15) x 10 10 dm 3 mol -1 s -1 . The H-adduct of adrenaline has two lambdasub(max), at 280 and 355 nm, with epsilon 280 = 420 m 2 mol -1 and epsilon 355 = 390 m 2 mol -1 , which disappears according to a first order reaction, k 1 = 1.4 x 10 3 s -1 . The spectra formed by 0H attack was assigned to the corresponding benzoxy radical with absorption maxima at 285 and 365 nm and epsilon 285 = 620 m 2 mol -1 and epsilon 365 = 105 m 2 mol -1 . Due to the overlapping of the intermediates, no decay kinetics could be obtained. (author)

Maleic acid and aluminum chloride catalyzed conversion of glucose to 5-(hydroxymethyl) furfural and levulinic acid in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ximing [Laboratory of Renewable Resources Engineering and Department of Agricultural and Biological Engineering; Purdue University; West Lafayette; USA; The Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio); Murria, Priya [The Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio); Discovery Park; Purdue University; West Lafayette; USA; Jiang, Yuan [The Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio); Discovery Park; Purdue University; West Lafayette; USA; Xiao, Weihua [Laboratory of Renewable Resources Engineering and Department of Agricultural and Biological Engineering; Purdue University; West Lafayette; USA; College of Engineering; Kenttämaa, Hilkka I. [The Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio); Discovery Park; Purdue University; West Lafayette; USA; Abu-Omar, Mahdi M. [The Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio); Discovery Park; Purdue University; West Lafayette; USA; Mosier, Nathan S. [Laboratory of Renewable Resources Engineering and Department of Agricultural and Biological Engineering; Purdue University; West Lafayette; USA; The Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio)

2016-01-01

Maleic acid (MA) and AlCl₃self-assemble into catalytic complexes (Al–(MA)₂–(OH)₂(aq)) with improved selectivity for converting glucose to HMF, and levulinic acid.

Formation of organic acids from trace carbon in acidic oxidizing media

International Nuclear Information System (INIS)

Terrassier, C.

2003-01-01

oxidation reactions by 3 N nitric acid identified in solution are also self-catalyzed by nitrous acid. Complete desorption of the carbon 14 in the dissolution off-gas assumes that ail the organic compounds in solution are mineralized. While the high molecular weight species are easily oxidized, acetic acid exhibits considerable stability in conventional dissolution media and its mineralization would require either very long residence times in nitrous fumes or the use of more powerful oxidizing agents in solution. (author) [fr

Synthesis of highly luminescent Mn:ZnSe/ZnS nanocrystals in aqueous media

International Nuclear Information System (INIS)

Fang Zheng; Wu Ping; Zhong Xinhua; Yang Yongji

2010-01-01

High-quality water-dispersible Mn 2+ -doped ZnSe core/ZnS shell (Mn:ZnSe/ZnS) nanocrystals have been synthesized directly in aqueous media. Overcoating a high bandgap ZnS shell around the Mn:ZnSe cores can bring forward an efficient energy transfer from the ZnSe host nanocrystals to the dopant Mn. The quantum yields of the dopant Mn photoluminescence in the as-prepared water-soluble Mn:ZnSe/ZnS core/shell nanocrystals can be up to 35 ± 5%. The optical features and structure of the obtained Mn:ZnSe/ZnS core/shell nanocrystals have been characterized by UV-vis, PL spectroscopy, TEM, XRD and ICP elementary analysis. The influences of various experimental variables, including the Mn concentration, the Se/Zn molar ratio as well as the kind and amount of capping ligand used in the core production and shell deposition process, on the luminescent properties of the obtained Mn:ZnSe/ZnS nanocrystals have been systematically investigated.

The reducibility of sulphuric acid and sulphate in aqueous solution

International Nuclear Information System (INIS)

Grauer, R.

1991-07-01

In connection with the Swedish project for final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister. A simple reaction between copper and sulphate is thermodynamically impossible, but copper can react to give copper sulphide if an additional electron donor such as iron(II) is available. The problem was extended to the more general question of the reducibility of sulphur(VI) in dilute aqueous solution. Chemical reduction of sulphate does not take place in dilute solution at temperatures below 100 o C. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300 o C. The oxidising action of sulphuric acid on metals becomes perceptible only at acid concentrations over 45-50%. In experiments on the cathodic reduction of 74% sulphuric acid the formation of hydrogen sulphide and elementary sulphur starts, depending on the current density, at 50-130 o C, and polarographic measurements suggest that the reducible species is not the hydrogen sulphate ion but molecular sulphuric acid. The resistance of copper to oxygen-free sulphuric acid up to a concentration of 60% is well-known. Numerous processes in industrial electrochemistry take place in sulphuric acid or sulphate electrolytes. The reversible metal/metal-sulphate electrodes of lead and cadmium are unstable relative to the corresponding metal sulphides. Nevertheless the reversible lead sulphate electrode does not fail from sulphide formation. All these facts confirm that sulphur(VI) in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be almost certainly be ruled out. (author) 5 figs., 85 refs

Effect of alpha irradiation on UO{sub 2} surface reactivity in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Jegou, C.; Muzeau, B.; Broudic, V.; Poulesquen, A.; Roudil, D. [Commissariat a l' Energie Atomique (CEA), Rhone Valley Research Center, DIEC/SESC/LMPA, Bagnols-sur-Ceze (France); Jorion, F. [Commissariat a l' Energie Atomique (CEA), Rhone Valley Research Center, DRCP/SE2A/LEMA, Bagnols-sur-Ceze (France); Corbel, C. [Commissariat a l' Energie Atomique (CEA), Saclay Research Center, DSM/DRECAM/SCM, Gif sur Yvette (France)

2005-07-01

The option of direct disposal of spent nuclear fuel in a deep geological formation raises the need to investigate the long-term behavior of the UO{sub 2} matrix in aqueous media subjected to {alpha}-{beta}-{gamma} radiation. The {beta}-{gamma} emitters account for most of the activity of spent fuel at the moment it is removed from the reactor, but diminish within a millennial time frame by over three orders of magnitude to less than the long-term activity. The latter persists over much longer time periods and must therefore be taken into account over a geological disposal time scale. Leaching experiments with solution renewal were carried out on UO{sub 2} pellets doped with alpha emitters ({sup 238}Pu and {sup 239}Pu) to quantify the impact of alpha irradiation on UO{sub 2} matrix alteration. Three batches of doped UO{sub 2} pellets with different alpha flux levels (3.30 x 10{sup 4}, 3.30 x 10{sup 5}, and 3.2 x 10{sup 6} {alpha} cm{sup -2} s{sup -1}) were studied. The results obtained in aerated and deaerated media immediately after sample annealing or interim storage in air provide a better understanding of the UO{sub 2} matrix alteration mechanisms under alpha irradiation. Interim storage in air of UO{sub 2} pellets doped with alpha emitters results in variations of the UO{sub 2} surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO{sub 2} pellet batches and spent fuel. Oxygen diffusion enhanced by alpha irradiation of the extreme surface layer and/or radiolysis of the air could account for the oxidation of the surface UO{sub 2} to UO{sub 2+x}. However, leaching experiments performed in deaerated media after annealing the samples and

Acidity and Structure of Isosaccharinate in Aqueous Solution: A Nuclear Magnetic Resonance Study

International Nuclear Information System (INIS)

Cho, Herman M.; Rai, Dhanpat; Hess, Nancy J.; Xia, Yuanxian; Rao, Linfeng

2003-01-01

Dilute aqueous solutions of the calcium and sodium salts of -D-isosaccharinate (ISA) have been analyzed by 13C and 1H NMR spectroscopy. The positions of the six 13C ISA NMR lines show a pH dependence that can be used to infer that the most acidic proton is the one associated with the carboxylate group, with a log k0 of -3.27 - -3.36 for the reaction H(ISA) H+ K ISA-

Rhenium(V) complexing with benzimidazole in acidic media

International Nuclear Information System (INIS)

Zakaeva, R.Sh.; Gagieva, S.Ch.; Kaloev, N.I.; Bukov, N.N.; Panyushkin, V.T.

2003-01-01

Coordination compounds of rhenium(V) with 1H-benzimidazole (L) separated from acid media: (HL) 2 [ReOX 5 ](H 2 O) n and [ReOL x X y (H 2 O) z ](H 2 O) n (HL and L - protonated and deprotonated forms of benzimidazole; X = Cl - , Br - ) were studied by the methods of IR spectroscopy, 1 H NMR spectroscopy and thermal gravimetric analysis. Methods of ligand coordination in the complexes are discussed on the basis of data obtained [ru

New thiamine functionalized silica microparticules as a sorbent for the removal of lead, mercury and cadmium ions in aqueous media

Directory of Open Access Journals (Sweden)

Deniz Sabahattin

2017-01-01

Full Text Available The existence of heavy metal ions in aqueous media is one of the biggest environmental pollution problems and thus the removal of heavy metals is a very important procedure. In this work, a new adsorbent was synthesized by modifying 3-aminopropyl-functionalized silica gel with thiamine (vitamin B1 and characterized. The influence of the uptake conditions, such as pH, contact time, initial feed concentration and foreign metal ions, on the binding capacity of thiamine-functionalized silica gel sorbent (M3APS were investigated. Maximum obtained adsorption capacities for Pb(II, Hg(II and Cd(II were 39.4±0.2, 30.9±0.5 and 9.54±0.4 mg g-1 M3APS, respectively, at pH 5.0. The observed selectivity of M3APS for these metal ions was the following: Pb(II > Hg(II > Cd(II. Adsorption isotherm models were also applied to the adsorption process. As a result, the Langmuir isotherm model gave the best fit for the adsorption of metal ions on M3APS. The Gibbs energy change (ΔG for the adsorption of Pb(II, Hg(II and Cd(II were calculated to predict the nature of adsorption process. Having such satisfactory adsorption results, M3APS is a potential candidate adsorbent for Pb(II and Hg(II removal from aqueous media.

Studies on rapid ion-exchange separation of the transplutonium elements with mineral acid-methanol mixed media

International Nuclear Information System (INIS)

Usuda, Shigekazu

1989-03-01

In order to study properties of short-lived transplutonium nuclides synthesized by heavy-ion bombardment, three methods for rapid separation of tri-valent transplutonium elements by ion-exchange chromatography with mineral acid-methanol mixed media at elevated temperature were investigated. The first separation method was anion-exchange chromatography with nitric acid-methanol mixed media. The second method was anion-exchange choromatography with dilute hydrochloric acid-methanol mixed media. The third method was improved cation-exchange chromatography with single-column operation using the mixed media of hydrochloric acid and methanol. The separation methods developed were found applicable to studies on synthesis of the trans-plutonium nuclides, 250 Fm (T 1/2 :30 min), 244,245,246 Cf (T 1/2 :20 min, 46 min and 35.7 h, respectively) from the 16 O + 238 U and 12 C + 242 Pu reactions, and on the decay property of 245 Cf. Attempts to search for new actinide nuclides, such as 240 U and neutron deficient nuclides of Am, Cm and Bk, were made by a quick purification. The separation system was also applied to the rapid and effective separation of Nd, Am and Cm from spent nuclear fuel samples, for burn-up determination. (J.P.N.) 242 refs

A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

International Nuclear Information System (INIS)

Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin

2015-01-01

Highlights: • The in-situ photo-grafting polymerization method was used to prepare the polymer film. • The synthesized MIF was layer stucture film. • The MIF exhibited good imprinting effect and highly selectivity. - Abstract: This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10 −12 –1 × 10 −8 mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R 2 = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10 −12 mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media

Study of the europium behavior in aqueous media; Estudio sobre el comportamiento del europio en medios acuosos

Energy Technology Data Exchange (ETDEWEB)

Fernandez R, E.; Jimenez R, M.; Solache R, M.; Martinez M, V. [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica, A.P. 18-1027, C.P. 11801 Mexico D.F. (Mexico)

2000-07-01

Europium as waste can produce a pollution problem in water that is in contact with it, what would has a heavy environmental impacts, because of the possibilities of diffusion of these wastes from their place of confinement or storage until the geo and biosphere. The solution of such problem requires of a lot of knowledge over the behavior of several chemical elements such as europium in aqueous solutions. In this work it was used a low ion force (0.02 M). The data set will allow extrapolate the hydrolytic behavior of europium in too much minors ion force media, such as the ground waters, including in ion force zero.

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

Energy Technology Data Exchange (ETDEWEB)

Pušnik, Klementina; Goršak, Tanja [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Jožef Stefan International Postgraduate School, 1000 Ljubljana (Slovenia); Drofenik, Miha [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Faculty of Chemistry and Chemical Engineering, University of Maribor, 2000 Maribor (Slovenia); Makovec, Darko [Department for Materials Synthesis, Jožef Stefan Institute, 1000 Ljubljana (Slovenia); Jožef Stefan International Postgraduate School, 1000 Ljubljana (Slovenia)

2016-09-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe{sup 3+}/Fe{sup 2+} ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles’ formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe{sup 3+} ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH. - Highlights: • Co-precipitation of Fe{sup 3+}/Fe{sup 2+} ions in the presence of aspartic amino acid (Asp). • Through analysis of nanoparticle formation mechanism. • Presence of Asp changes the mechanism of the nanoparticles’ formation. • Asp forms a coordination complex with the Fe{sup 3+} ions. • Asp impedes the formation of iron oxyhydroxide phase and suppresses the growth of iron-oxide nanoparticles. • The aspartic-acid-absorbed nanoparticles form stable aqueous suspensions.

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

International Nuclear Information System (INIS)

Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

2016-01-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe 3+ /Fe 2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles’ formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe 3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH. - Highlights: • Co-precipitation of Fe 3+ /Fe 2+ ions in the presence of aspartic amino acid (Asp). • Through analysis of nanoparticle formation mechanism. • Presence of Asp changes the mechanism of the nanoparticles’ formation. • Asp forms a coordination complex with the Fe 3+ ions. • Asp impedes the formation of iron oxyhydroxide phase and suppresses the growth of iron-oxide nanoparticles. • The aspartic-acid-absorbed nanoparticles form stable aqueous suspensions.

Phosphoric acids as amplifiers of molecular chirality in liquid crystalline media

NARCIS (Netherlands)

Eelkema, R; Feringa, BL

2006-01-01

A new system for the double amplification of the molecular chirality of simple chiral amines in achiral liquid crystalline media is described. It involves a conformationally flexible phosphoric acid based receptor that by binding to chiral amines induces chirality in the liquid crystalline matrix.

Redox thermodynamic data of plutonium in acidic and carbonate media. Pu(V) stability

International Nuclear Information System (INIS)

Capdevila, H.

1992-01-01

Pu redox equilibria are studied in acidic and carbonate media in this thesis, to build a thermodynamic data bank consistent with the TDB (NEA-OECD) one and in connection with radioactive waste disposal programs. Literature is discussed and reinterpreted. The experimental method is tested with Uranium preliminary measurements. The reversible redox potentials (PuO 2 + and Pu 4+ /Pu 3+ ) are measured using the cyclic voltametric technique in perchloric media at several ionic strengths (from 0.5 to 3M) and temperatures (from 0 to 70 deg C). The Specific Interaction Theory (SIT) is used to measured activity coefficients and to extrapolate data to the standard conditions. The potentials variations versus temperature are linear in first approximation: the entropy changes are found constant from 0 to 70 deg C and the heat capacity changes are within uncertainties. The standard constant of PuO 2 + disproportionation into PuO 2 2+ and Pu 3+ is deduced from spectrophotometric measurements performed in perchloric media around pH=1 where Pu 4+ hydrolysis is discussed. The Pu non-reversible standard potentials (PuO 2 2+ /Pu 4+ for instance) are then calculated and validated with a spectrophotometric study of Pu 4+ formation from PuO 2 2+ and Pu 3+ in a 1M perchloric acidic solution. The Pu(VI/V) redox potential, activity coefficients and entropies are measured using the same technique in concentrated carbonate media. The limiting complex standard formation constants and the redox potential shifts (between acidic and carbonate media) are then discussed among the U, Np, Pu and Am actinides. A spectrophotometric study of the equilibrium between the complexes with 5 and 4 carbonate ligands allowed to measure Pu(IV) limiting complex stability at several ionic strengths. (author). 26 tabs., 46 figs., 95 refs

Microwave discharge electrodeless lamps (MDEL). Part VII. Photo-isomerization of trans-urocanic acid in aqueous media driven by UV light from a novel Hg-free Dewar-like microwave discharge thermally-insulated electrodeless lamp (MDTIEL). Performance evaluation.

Science.gov (United States)

Horikoshi, Satoshi; Sato, Tatsuro; Sakamoto, Kazutami; Abe, Masahiko; Serpone, Nick

2011-07-01

A novel mercury-free Dewar-like (double-walled structure) microwave discharge thermally-insulated electrodeless lamp (MDTIEL) was fabricated and its performance evaluated using the photo-isomerization of trans-urocanic acid (trans-UA) in aqueous media as a test process driven by the emitted UV light when ignited with microwave radiation. The photo-isomerization processes trans-UA → cis-UA and cis-UA → trans-UA were re-visited using light emitted from a conventional high-pressure Hg light source and examined for the influence of UV light irradiance and solution temperature; the temperature dependence of the trans → cis process displayed a negative activation energy, E(a) = -1.3 cal mol(-1). To control the photo-isomerization of urocanic acid from the heat usually dissipated by a microwave discharge electrodeless lamp (single-walled MDEL), it was necessary to suppress the microwave-initiated heat. For comparison, the gas-fill in the MDEL lamp, which typically consists of a mixture of Hg and Ar, was changed to the more eco-friendly N(2) gas in the novel MDTIEL device. The dynamics of the photo-isomerization of urocanic acid driven by the UV wavelengths of the N(2)-MDTIEL light source were compared to those from the more conventional single-walled N(2)-MDEL and Hg/Ar-MDEL light sources, and with those from the Hg lamp used to irradiate, via a fiber optic, the photoreactor located in the wave-guide of the microwave apparatus. The heating efficiency of a solution with the double-walled N(2)-MDTIEL was compared to the efficiency from the single-walled N(2)-MDEL device. Advantages of N(2)-MDTIEL are described from a comparison of the dynamics of the trans-UA → cis-UA process on the basis of unit surface area of the lamp and unit power consumption. The considerably lower temperature on the external surface of the N(2)-MDTIEL light source should make it attractive in carrying out photochemical reactions that may be heat-sensitive such as the photothermochromic

Extraction of zirconium(IV) and separation of 95Zr-95Nb from acidic thiocyanate media by LIX 54 and its mixtures with TBP

International Nuclear Information System (INIS)

Mishra, P.K.; Chakravortty, V.; Dash, K.C.; Das, N.R.; Bhattacharyya, S.N.

1990-01-01

Appreciable extraction of 95 Zr- 95 Nb by LIX 54 from aqueous HCl alone is not observed in the concentration range from 0.1 to 2 M HCl. Presence of thiocyanate ions results in appreciable extraction of this pair from such acid medium. Synergism has been observed in the extraction of zirconium(IV) by mixtures of LIX 54 and TBP from thiocyanate media, whereas there has been no appreciable synergism in case of niobium(V) under identical conditions. Slope analyses indicate the species extracted by pure TBP to be disolvate whereas for extraction by the mixtures of LIX 54 and TBP it is found to be monosolvate with respect to TBP. The extraction of both the metal ions have been found to depend on the concentration of acid as well as that of thiocyanate ions. Extraction increases with increase in percentage of either of the extractants. Effective separation of these congeneric pairs has been achieved by suitable choice of above system. Extraction is independent of aq. zirconium concentration up to 0.01 M above which it decreases. (orig.)

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.

Study of the interaction metallic cation - ligand in concentrated phosphorus acid media; Etude de l'interaction cation metallique - ligand en milieu acide phosphorique concentre

Energy Technology Data Exchange (ETDEWEB)

Sefiani, N.; Azzi, M.; Hlaibi, M. [Faculte des Sciences Ain Chock, Laboratoire d' Electrochimie et Chimie de l' Environnement (LECE), Casablanca (Morocco); Kossair, A. [Centre de Recherche des Phosphates Mineraux (CERPHOS), Casablanca (Morocco)

2005-07-01

The phosphoric acid is more and more used with a high purity. The recovery of recycling element (uranium, vanadium, rare earth...) and the elimination of toxic element (cadmium, molybdenum, lead...) contained in the phosphoric acid are generally realized by extraction or precipitation. It is then very important to understand these impurities behavior in the phosphoric media in order to control their elimination. In this work, the authors considered the presence of some metallic cations (V, Al, fe, U) and fluorides ions as impurity in concentrated phosphoric acid media. (A.L.B.)

Inhibition of ice crystallisation in highly viscous aqueous organic acid droplets

Directory of Open Access Journals (Sweden)

B. J. Murray

2008-09-01

Full Text Available Homogeneous nucleation of ice within aqueous solution droplets and their subsequent crystallisation is thought to play a significant role in upper tropospheric ice cloud formation. It is normally assumed that homogeneous nucleation will take place at a threshold supersaturation, irrespective of the identity of the solute, and that rapid growth of ice particles will follow immediately after nucleation. However, it is shown here through laboratory experiments that droplets may not readily freeze in the very cold tropical tropopause layer (TTL, typical temperatures of 186–200 K. In these experiments ice crystal growth in citric acid solution droplets did not occur when ice nucleated below 197±6 K. Citric acid, 2-hydroxypropane-1,2,3-tricarboxyllic acid, is a molecule with similar functionality to oxygenated organic compounds which are ubiquitous in atmospheric aerosol. It is therefore thought to be a sensible proxy for atmospheric organic material. Evidence is presented that suggests citric acid solution droplets become ultra-viscous and form glassy solids under atmospherically relevant conditions. Diffusion of liquid water molecules to ice nuclei is expected to be very slow in ultra-viscous solution droplets and nucleation is negligible in glassy droplets; this most likely provides an explanation for the experimentally observed inhibition of ice crystallisation. The implications of ultra-viscous and glassy solution droplets for ice cloud formation and supersaturations in the TTL are discussed.

Quenching characteristics of bathocuproinedisulfonic acid, disodium salt in aqueous solution and copper sulfate plating solution

Science.gov (United States)

Koga, Toshiaki; Hirakawa, Chieko; Takeshita, Michinori; Terasaki, Nao

2018-04-01

Bathocuproinedisulfonic acid, disodium salt (BCS) is generally used to detect Cu(I) through a color reaction. We newly found BCS fluorescence in the visible blue region in an aqueous solution. However, the fluorescence mechanism of BCS is not well known, so we should investigate its fundamental information. We confirmed that the characteristics of fluorescence are highly dependent on the molecular concentration and solvent properties. In particular, owing to the presence of the copper compound, the fluorescence intensity extremely decreases. By fluorescence quenching, we observed that a copper compound concentration of 10-6 mol/L or less could easily be measured in an aqueous solution. We also observed BCS fluorescence in copper sulfate plating solution and the possibility of detecting monovalent copper by fluorescence reabsorption.

Phytochemical constituents and antioxidant activities of aqueous ...

African Journals Online (AJOL)

Furthermore, total phenolic content in aqueous extract (0.66 ± 0.02 mg gallic acid equivalent/g) was significantly higher (p < 0.05) than methanol extract (0.52 ± 0.01 mg gallic acid equivalent/g). In addition, inhibition of lipid peroxidation by aqueous extract (80.60 ± 0.28%) was significantly higher (p < 0.05) than methanol ...

THIOGLYCOLIC ACID ESTERIFIED IN TO RICE STRAW FOR REMOVING LEAD FROM AQUEOUS SOLUTION

Directory of Open Access Journals (Sweden)

R. Gong

2011-09-01

Full Text Available Thiol rice straw (TRS was prepared by esterifying thioglycolic acid onto rice straw in the medium of acetic anhydride and acetic acid with sulfuric acid as catalyst. The sorption of lead (Pb on TRS from aqueous solution was subsequently investigated. The batch experiments showed that Pb removal was dependent on initial pH, sorbent dose, Pb concentration, contact time, and temperature. The maximum value of Pb removal appeared at pH 5. For 100 mg/L of Pb solution, a removal ratio of greater than 98% could be achieved with 2.0 g/L or more of TRS. The isothermal data of Pb sorption conformed well to the Langmuir model, and the maximum sorption capacity (Qm of TRS for Pb was 104.17 mg/g. The equilibrium of Pb removal was reached within 120 min. The Pb removal process could be described by the pseudo-first-order kinetic model. The thermodynamic study indicated that the Pb removal process was spontaneous and endothermic.

Sorption behaviour of uranium and thorium on hydrous tin oxide from aqueous and mixed-solvent HNO3 media

International Nuclear Information System (INIS)

Misak, N.Z.; Salama, H.N.; El-Naggar, I.M.

1983-01-01

In aqueous nitric acid, uranyl and thorium ions seem to be sorbed on hydrous tin oxide mainly by a cation exchange mechanism. In 10 - 3 M aqueous solutions, the hydrous oxide prefers thorium to uranium at the relative low pH values, while the reverse is true at the higher pH values. The exchange of uranium is particle diffusion controlled while that of thorium is chemically controlled, and the isotherms point to the presence of different-energy sites in the hydrous oxide. Except for the solutions containing 80% of methanol, ethanol, or acetone, cation exchange is probably still the main mechanism of sorption of uranium. Anionic sorption of thorium seems to occur in all the mixed-solvent solutions and is perhaps the main mechanism in 80% ethanol. The equilibrium distribution coefficient K sub (d) increases almost in all cases with organic solvent content, probably due to dehydration of sorbed ions and to increasing superposition on anionic sorption. Unlike the aqueous medium, large U/Th separation factors are achieved in many of the mixed-solvent solutions and separation schemes are suggested. (Authors)

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.

Use of cationites for separation of transplutonium elements from other elements from aqueous and aqua-alcohol solutions of hydrochloric and nitric acids

International Nuclear Information System (INIS)

Guseva, L.I.; Tikhomirova, G.S.

1984-01-01

The behaviour of Am, Cm, Pu and certain fragment elements (Cs, Sr, Y, Zr, Nb, Ru, Eu) on cationite dauex-50 in aqueous and aqueous-alcohol solutions of HCl and HNO 3 has been studied. Dependences of distribution coefficients and separation factors of the elements on the acid concentration and alcohol content in the solutions are presented. The sorption of TPE by cationite from HCl and HNO 3 solutions in the presence of alcohol is shown to increase over the range of concentrations studied (from 0.5 mol/L to 4-5 mol/L), which is explained by the salting-out effect of alcohol. The distribution coefficients of TPE in the solutions, containing >= 50% alcohol, constitute >= 10 2 . The distribution coefficients of the fragment elements in the presence of alcohol also increase, but to a considerably lesser extent, which results in a better separation. The study of the washing-out curves has shown that, to separate TPE from fragment elements on cationites, both HCl and HNO 3 solutions can be used, at that, in the case of aqueous solutions a better separation is attained at acid concentration, equal to 1 mol/L, and in the case of eluating by aqueous-alcohol solutions a good separation is achieved at hig-her concentrations of the acids as well

Absorption mechanisms for cationic and anionic mineral species on ferric iron polymer hydroxides and oxidation products of ferrous iron in aqueous media

International Nuclear Information System (INIS)

Gandon, Remi

1982-01-01

Adsorbents obtained by hydrolysing the Fe 3+ , 6H 2 O ion are made of polymers with aquo (H 2 O), hydroxo (-OH...) and oxo (...O...) ligands. Radioactive tracers reveal the importance of chemical mechanisms in adsorption phenomena on ferric oxide in aqueous media. Zn 2+ , Co 2+ and Mn 2+ cations are exchanged with hydrogen from hydroxo groups. CrO 4 2- , SeO 3 2- and Sb(OH) 6 - anions form covalent associations in place of iron ligands. The adsorption of hydrolyzed ions results in strong oxygen bridge bonds. In fresh water, Co and Mn participate alone in physical electrostatic adsorption. Iron II oxidation products generate chemical adsorptions. Zn 2+ and Sb(OH) 6 - associate with ferric hydroxides from oxidized Fe 2+ . 60 Co, 54 Mn and 51 Cr form covalent associations between unpaired 3d iron electrons and the adsorbed element. This process is not predominant with selenium IV or VI reduced to the metallic state or fixed on ferric hydroxide in the selenite form. These conclusions can be applied to pollutant analysis and to water purification and contribute to our understanding of the role of iron in the distribution of oligo-elements in aqueous media. (author) [fr

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

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles

International Nuclear Information System (INIS)

Chen Jian; Zeng Fang; Wu Shuizhu; Su Junhua; Zhao Jianqing; Tong Zhen

2009-01-01

A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu 2+ in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu 2+ ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu 2+ ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu 2+ ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu 2+ /PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu 2+ detection is 1 μM for a nanoparticle sample with a diameter of ∼30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu 2+ ion among the metal ions examined (Na + , K + , Mg 2+ , Ca 2+ , Zn 2+ , Hg 2+ , Mn 2+ , Fe 2+ , Ni 2+ , Co 2+ and Pb 2+ ). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles.

Science.gov (United States)

Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

2009-09-09

A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu(2+) in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu(2+) ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu(2+) ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu(2+) ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu(2+)/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu(2+) detection is 1 microM for a nanoparticle sample with a diameter of approximately 30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu(2+) ion among the metal ions examined (Na(+), K(+), Mg(2+), Ca(2+), Zn(2+), Hg(2+), Mn(2+), Fe(2+), Ni(2+), Co(2+) and Pb(2+)). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles

Science.gov (United States)

Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

2009-09-01

A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu2+ in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu2+ ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu2+ ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu2+ ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu2+/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu2+ detection is 1 µM for a nanoparticle sample with a diameter of ~30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu2+ ion among the metal ions examined (Na+, K+, Mg2+, Ca2+, Zn2+, Hg2+, Mn2+, Fe2+, Ni2+, Co2+ and Pb2+). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

Extremophile mediated hydrogen production for hydrogenation of substrates in aqueous media

Science.gov (United States)

Anjom, Mouzhgun

Catalytic hydrogenation reactions are pervasive throughout our economy, from production of margarine as food, liquid fuels for transportation and chiral drugs such as L-DOPA. H2 production from non-fossil fuel feedstocks is highly desirable for transition to the "Hydrogen Economy". Also, the rates of hydrogenation reactions that involve a substrate, H 2 gas and a catalyst are often limited by the solubility of H2 in solvent. The present research thus envisioned designing water-soluble catalysts that could effectively utilize biologically produced H2 in a coupled system to hydrogenate substrates in homogeneous mode (two-phase system). Biological production of H2 as an end product or byproduct of the metabolism of organisms that operate under strict anaerobic conditions has been proposed. However, contrary to what was previously observed, Thermotoga neapolitana, belonging to the order of Thermotogales efficiently produces H2 gas under microaerobic conditions (Van Ooteghem et al. 2004). For H2 production by T. neapolitana in the bacterial growth medium (DSM 5068) at an optimum temperature of 70 C, our results in batch mode show that: (1) H2 was produced from glucose though with 16% efficiency, the rest goes to biomass production, (2) H2 gas was produced even when the cultures were inoculated under microaerobic conditions (up to 8% (v/v) O2) suggesting a protective mechanism for one or more [Fe-Fe] hydrogenases in T. neapolitana, (3) H2 production was pH dependent but addition of simple, non-toxic physiological buffering additives such as Methylene succinic acid increased H2 production and (4) H2 production rate varied linearly in the 100--6800 kPa pressure range. We then screened various water-soluble metal catalysts in batch mode and selected the RhCl3.3H2O/TPPTS (TPPTS is a water-soluble ligand) system that achieved 86% hydrogenation of Methylene succinic acid (an olefin) in an aqueous medium pressurized with preformed H2. When water was replaced with the DSM 5068

Kinetics and Mechanism of Oxidation of Aromatic Aldehydes by Imidazolium Dichromate in Aqueous Acetic Acid Medium

Directory of Open Access Journals (Sweden)

S. Sheik Mansoor

2009-01-01

Full Text Available The kinetics of oxidation of benzaldehyde (BA and para-substituted benzaldehydes by imidazolium dichromate (IDC has been studied in aqueous acetic acid medium in the presence of perchloric acid. The reaction is first order each in [IDC], [Substrate] and [H+]. The reaction rates have been determined at different temperatures and the activation parameters calculated. Electron withdrawing substituents are found to increase the reaction and electron releasing substituents are found to retard the rate of the reaction and the rate data obey the Hammett relationship. The products of the oxidation are the corresponding acids. The rate decreases with the increase in the water content of the medium. A suitable mechanism is proposed.

Determination of free acid in highly concentrated organic and aqueous solutions of plutonium (IV) and uranium (VI) nitrate

International Nuclear Information System (INIS)

Wagner, J.F.; Lacour, J.L.

1989-01-01

Free acidity is an important parameter in the nuclear reprocessing control. The accuracy on the determination of free acidity is not really required in the nuclear reprocessing control itself but is necessary for certain types of analysis such as spectrophotometry (Pu (VI), Am (III),...), density determinations. A new titripotentiometric method for free acidity determination in concentrated U(VI) and Pu(IV) solutions is presented. This method is based on the complexing properties of dipicolinic acid (pyridine 2.6 dicarboxylic acid) and medium effect with H 2 O/DMSO mixture. This method can be used either in organic or aqueous phases with ratio /H + I/ metal ≥ 5.10 -2 and a relative standard deviation of 1%

Comparing the acidities of aqueous, frozen, and freeze-dried phosphate buffers: Is there a "pH memory" effect?

Science.gov (United States)

Vetráková, Ľubica; Vykoukal, Vít; Heger, Dominik

2017-09-15

The concept of "pH memory" has been established in the literature for the correlation between the pH of a pre-lyophilization solution and the ionization state of freeze-dried powder (lyophile). In this paper, the concept of "pH memory" is explored for the system of an aqueous solution, a frozen solution, and a lyophile. Sodium and potassium phosphate buffers in the pH range of 5-9 were frozen and lyophilized with sulfonephthalein indicators as acidity probes, and their Hammett acidity functions were compared to the initial pH of the aqueous solution. The results show that the acidities of the lyophiles are somewhat changed compared to the initial pHs, but the acidities in the frozen state differ more substantially. The Hammett acidity functions of the frozen buffers were found to be markedly dissimilar from the initial pH, especially in the sodium phosphate frozen at 233K, where an increase in the initial pH led to a decrease in the Hammett acidity function of the frozen state at a certain pH range. The large acidification observed after freezing the sodium phosphate buffer was not detected in the lyophiles after the sample had been dried; the phenomenon is explained considering the formed crystals analyzed by X-ray powder diffraction. The results suggest that monitoring the final acidity of a lyophile is not sufficient to predict all the acidity changes throughout the whole lyophilization process. The importance of well-controlled freezing and lyophilization conditions follows from the results of the research. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin, E-mail: txwei@bit.edu.cn

2015-07-01

Highlights: • The in-situ photo-grafting polymerization method was used to prepare the polymer film. • The synthesized MIF was layer stucture film. • The MIF exhibited good imprinting effect and highly selectivity. - Abstract: This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10{sup −12}–1 × 10{sup −8} mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R{sup 2} = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10{sup −12} mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media.

On the selection of the anode material for the electrochemical removal of methylparaben from different aqueous media

International Nuclear Information System (INIS)

Steter, Juliana R.; Brillas, Enric; Sirés, Ignasi

2016-01-01

found in all media regardless of the anode, although the mineralization was decelerated owing to the accumulation of chlorinated by-products. GC-MS and HPLC analysis allowed the identification of up to seven aromatic MeP derivatives in sulfate + chloride mixtures, including three non-chlorinated compounds also found in pure sulfate medium. These molecules were gradually transformed into oxalic acid, along with four chlorinated aliphatic carboxylic acids in Cl − -containing media.

Biosorption of formic and acetic acids from aqueous solution using activated carbon from shea butter seed shells

Science.gov (United States)

Adekola, Folahan A.; Oba, Ismaila A.

2017-10-01

The efficiency of prepared activated carbon from shea butter seed shells (SB-AC) for the adsorption of formic acid (FA) and acetic acid (AA) from aqueous solution was investigated. The effect of optimization parameters including initial concentration, agitation time, adsorbent dosage and temperature of adsorbate solution on the sorption capacity were studied. The SB-AC was characterized for the following parameters: bulk density, moisture content, ash content, pH, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optimal conditions for the adsorption were established and the adsorption data for AA fitted Dubinin-Radushkevich (D-R) isotherm well, whereas FA followed Langmuir isotherm. The kinetic data were examined. It was found that pseudo-second-order kinetic model was found to adequately explain the sorption kinetic of AA and FA from aqueous solution. It was again found that intraparticle diffusion was found to explain the adsorption mechanism. Adsorption thermodynamic parameters were estimated and the negative values of Δ G showed that the adsorption process was feasible and spontaneous in nature, while the negative values of Δ H indicate that the adsorption process was exothermic. It is therefore established that SB-AC has good potential for the removal of AA and FA from aqueous solution. Hence, it should find application in the regular treatment of polluted water in aquaculture and fish breeding system.

Critical review of the chemistry and thermodynamics of technetium and some of its inorganic compounds and aqueous species

International Nuclear Information System (INIS)

Rard, J.A.

1983-01-01

Chemical and thermodynamic data for Technetium (Tc) and some of its inorganic compounds and aqueous species are reviewed here. Major emphasis is given to systems with potential geochemical applications, especially the geochemistry of radioactive waste disposal. Compounds considered include oxides, hydroxides, hydrates oxides, halides, oxyhalides, double halides, and sulfides. The aqueous species considered include those in both noncomplexing media (pertechnetates, technetates, aquo-ions, and hydrolyzed cations) and complexing media (halides, sulfates, and phosphates). Thermodynamic values are recommended for specific compounds and aqueous ions when reliable experimental data are available. Where thermodynamic data are inadequate or unavailable, the chemistry is still discussed to provide information about what needs to be measured, and which chemistry needs to be clarified. A major application of these thermodynamic data will be for chemical equilibrium modeling and for construction of potential-pH diagrams for aqueous solutions. Unfortunately, the present lack of data precludes such calculations for complexing aqueous media. The situation is much better for noncomplexing aqueous media, but the chemistry and thermodynamics of cationic Tc(V) species and hydrolyzed Tc(III) species are poorly understood. 240 references, 6 tables

Reactive transport of aqueous protons in porous media

KAUST Repository

McNeece, Colin J.; Hesse, Marc A.

2016-01-01

and total aqueous proton concentrations. An inflection point in this function near neutral pH leads to a reversal in the classic front formation mechanism under basic conditions, such that proton desorption leads to a self-sharpening front, while adsorption

One-pot synthesis of amino acid precursors with insoluble organic matter in planetesimals with aqueous activity

Science.gov (United States)

Kebukawa, Yoko; Chan, Queenie H. S.; Tachibana, Shogo; Kobayashi, Kensei; Zolensky, Michael E.

2017-01-01

The exogenous delivery of organic molecules could have played an important role in the emergence of life on the early Earth. Carbonaceous chondrites are known to contain indigenous amino acids as well as various organic compounds and complex macromolecular materials, such as the so-called insoluble organic matter (IOM), but the origins of the organic matter are still subject to debate. We report that the water-soluble amino acid precursors are synthesized from formaldehyde, glycolaldehyde, and ammonia with the presence of liquid water, simultaneously with macromolecular organic solids similar to the chondritic IOM. Amino acid products from hydrothermal experiments after acid hydrolysis include α-, β-, and γ-amino acids up to five carbons, for which relative abundances are similar to those extracted from carbonaceous chondrites. One-pot aqueous processing from simple ubiquitous molecules can thus produce a wide variety of meteoritic organic matter from amino acid precursors to macromolecular IOM in chondrite parent bodies. PMID:28345041

A systematic investigation and insight into the formation mechanism of bilayers of fatty acid/soap mixtures in aqueous solutions.

Science.gov (United States)

Xu, Wenlong; Song, Aixin; Dong, Shuli; Chen, Jingfei; Hao, Jingcheng

2013-10-08

Vesicles are the most common form of bilayer structures in fatty acid/soap mixtures in aqueous solutions; however, a peculiar bilayer structure called a "planar sheet" was found for the first time in the mixtures. In the past few decades, considerable research has focused on the formation theory of bilayers in fatty acid/soap mixtures. The hydrogen bond theory has been widely accepted by scientists to explain the formation of bilayers. However, except for the hydrogen bond, no other driving forces were proposed systematically. In this work, three kinds of weak interactions were investigated in detail, which could perfectly demonstrate the formation mechanism of bilayer structures in the fatty acid/soap mixtures in aqueous solutions. (i) The influence of hydrophobic interaction was detected by changing the chain length of fatty acid (C(n)H(2n+1)COOH), in which n = 10 to 18, the phase behavior was investigated, and the phase region was presented. With the help of cryogenic transmission electron microscopy (cryo-TEM) observations, deuterium nuclear magnetic resonance ((2)H NMR), and X-ray diffraction (XRD) measurements, the vesicles and planar sheets were determined. The chain length of C(n)H(2n+1)COOH has an important effect on the physical state of the hydrophobic chain, resulting in an obvious difference in the viscoelasticity of the solution samples. (ii) The existence of hydrogen bonds between fatty acids and their soaps in aqueous solutions was demonstrated by Fourier transform infrared (FT-IR) spectroscopy and molecule dynamical simulation. From the pH measurements, the pH ranges of the bilayer formation were at the pKa values of fatty acids, respectively. (iii) Counterions can be embedded in the stern layer of the bilayers and screen the electrostatic repulsion between the COO(-) anionic headgroups. FT-IR characterization demonstrated a bidentate bridging coordination mode between counterions and carboxylates. The conductivity measurements provided the degree

Aerobic oxidation of aqueous ethanol using heterogeneous gold catalysts: Efficient routes to acetic acid and ethyl acetate

DEFF Research Database (Denmark)

Jørgensen, Betina; Christiansen, Sofie Egholm; Thomsen, M.L.D.

2007-01-01

The aerobic oxidation of aqueous ethanol to produce acetic acid and ethyl acetate was studied using heterogeneous gold catalysts. Comparing the performance of Au/MgAl2O4 and Au/TiO2 showed that these two catalysts exhibited similar performance in the reaction. By proper selection of the reaction...

Zirconia sol-gel coatings deposited on 304 stainless steel for chemical protection in acid media

International Nuclear Information System (INIS)

Luna, F. Perdomo; Atik, M.; Avaca, Luis A.; Aegerter, M.A.

1995-01-01

Zr O 2 thin films were prepared by sol-gel method and using dip-coating technique for deposition on 304 austenitic stainless steel, from sonocatalyzed sols of zirconia alkoxide, isopropanol (Zr(O C 3 H 7 )4/C 3 H 7 OH = 0.5), glacial acetic acid and water (C H 3 CO OH/H 2 O = 0.5). The films were dried at 40 deg C/15 min and thermally treated in the air with a linear variation of 5 deg C/min and two isothermal holdings at 400 deg C during 1 h and afterwards at 800 deg C during several periods of time (up to 20 h). The film thickness ranges between 0.6 and 0.8 μm. Structure and morphology were studied by x-ray diffraction and scanning electron microscopy. The corrosion potential, the corrosion current density, the polarization resistance and the corrosion rate (mpy) in 1,0 N aqueous solution of H 2 SO 4 at room temperature were determined using potentiometric polarization curves with a scanning velocity of 1 mV/s. These films act as a blocking physical layer in the corrosion media and increase the substrate life time in a factor of 7

Aldehydes, ketones, and carboxylic acids formed radiolytically in aqueous solutions of cyanides and simple nitriles

International Nuclear Information System (INIS)

Negron-Mendoza, A.; Draganic, Z.D.; Navarro-Gonzalez, R.; Graganic, I.G.

1983-01-01

A systematic search for aldehydes, ketones, and carboxylic acids was carried out in aqueous solutions of HCN, NH 4 CN, CH 3 CN, and C 2 H 4 CN, that had received multikilogray doses of 60 Co γ radiation. About 30 radiolytic products were identified, among them a large variety of dicarboxylic and tricarboxylic acids. Some of them might be of significant interest in molecular evolution studies of prebiotic processes. They originate in the free-radical-initiated chemical reactions where the additional oligomerization processes are particularly important. Most of the radiolytic products appear in both cyanides and nitriles and point to the importance of reactions involving the carbon-nitrogen triple bond

Study of 3-Ethylamino-but-2-enoic acid phenylamide as a new ligand for preconcentration of lanthanides from aqueous media by liquid-liquid extraction prior to ICP-MS analysis.

Science.gov (United States)

Varbanova, Evelina K; Angelov, Plamen A; Stefanova, Violeta M

2016-11-01

In the present work the potential of a new ligand 3-Ethylamino-but-2-enoic acid phenylamide (representing the class of enaminones) for selective preconcentration of lanthanides (La, Ce, Eu, Gd and Er) from aqueous medium is examined. Liquid-liquid extraction parameters, such as pH of the water phase, type and volume of organic solvent, quantity of ligand and reaction time are optimized on model solutions. Recovery of lanthanides by re-extraction with nitric acid makes the LLE procedure compatible with Inductively Coupled Plasma Mass Spectrometry. Spectral and non-spectral interferences are studied. Two isotopes per element are measured (with exception of La) for dynamic evaluation of the potential risk of spectral interference in variable real samples. The selectivity of complex formation reaction towards concomitant alkali and alkali-earth elements eliminates the interferences from sample matrix. Subjecting the standards to the optimized extraction procedure in combination with Re as internal standard is recommended as calibration strategy. The accuracy of developed method is approved by analysis of CRM Bush branches and leaves (NCS DC 73348) and recovery of spiked water and plant samples. The method's limits of detection for both studied objects are in the ranges from 0.2 ((158)Gd) to 3.7 ((139)La) ngl(-1) and 0.02 ((158)Gd) to 0.37((139)La) ngg(-1) for waters and plants respectively. The studied compound is an effective new ligand for preconcentration/separation of lanthanides from aqueous medium by LLE and subsequent determination by ICP-MS. Copyright © 2016 Elsevier B.V. All rights reserved.

Process for the preparation of lactic acid and glyceric acid

Science.gov (United States)

Jackson, James E [Haslett, MI; Miller, Dennis J [Okemos, MI; Marincean, Simona [Dewitt, MI

2008-12-02

Hexose and pentose monosaccharides are degraded to lactic acid and glyceric acid in an aqueous solution in the presence of an excess of a strongly anionic exchange resin, such as AMBERLITE IRN78 and AMBERLITE IRA400. The glyceric acid and lactic acid can be separated from the aqueous solution. Lactic acid and glyceric acid are staple articles of commerce.

Using Eggshell in Acid Orange 2 Dye Removal from Aqueous Solution

Directory of Open Access Journals (Sweden)

Ahmad Reza Yari

2015-05-01

Full Text Available Background and purpose: Generated dye wastewater by the textile industry is usually toxic, non-biodegradable and resistant in the environment. Eggshell is one of the inexpensive material and for the reason the vesicular structures can be used as a proper adsorbent for pollutants removal. The aim of this study is to investigate the efficiency of eggshell for removal of acid orange 2 dye from aqueous solution. Materials and Methods: In the experimental study was determined the efficacy of variant variables such as contact time (15, 30, 60, 90 and 120 min, pH (3, 7 and 11, adsorbent dose (10, 25, 50 and 75 g/L, and initial dye concentration (25, 50 and 100 mg/L. The concentration of dye by spectrophotometer ultraviolet/visible in the wavelength 483 nm was examined. Results: The results showed that with increasing contact time and adsorbent dose, the dye removal efficiency was increased, but with increasing pH and initial dye concentration the removal efficiency was decreased. The maximum of removal efficiency of acid orange 2 dye got in the optimum pH: 3, contact time: 90 min, adsorbent dose: 50 g/L and initial dye concentration: 25 mg/L. Adsorption of acid orange 2 dye (R2 = 0.87 follow the Freundlich isotherm. Conclusion: Eggshells can be used as an inexpensive and effective adsorbent for the removal of acid orange 2 dye.

Aqueous lithium air batteries

Science.gov (United States)

Visco, Steven J.; Nimon, Yevgeniy S.; De Jonghe, Lutgard C.; Petrov, Alexei; Goncharenko, Nikolay

2017-05-23

Aqueous Li/Air secondary battery cells are configurable to achieve high energy density and prolonged cycle life. The cells include a protected a lithium metal or alloy anode and an aqueous catholyte in a cathode compartment. The aqueous catholyte comprises an evaporative-loss resistant and/or polyprotic active compound or active agent that partakes in the discharge reaction and effectuates cathode capacity for discharge in the acidic region. This leads to improved performance including one or more of increased specific energy, improved stability on open circuit, and prolonged cycle life, as well as various methods, including a method of operating an aqueous Li/Air cell to simultaneously achieve improved energy density and prolonged cycle life.

Modelling and Optimization of Corrosion Inhibition of Mild Steel in Phosphoric Acid by Red Pomegranate Peels Aqueous Extract

Directory of Open Access Journals (Sweden)

Khalid Hamid Rashid

2011-11-01

Full Text Available Taguchi experimental design (TED is applied to find the optimum effectiveness of aqueous Red Pomegranate Peel (RPP extract as a green inhibitor for the corrosion of mild steel in 2M H3PO4 solution. The Taguchi methodology has been used to study the effects of changing, temperature, RPP concentration and contact period, at three levels. Weight-loss measurements were designed by construction a L9 orthogonal arrangement of experiments. Results of the efficiencies of inhibition were embraced for the signal to noise proportion & investigation of variance (ANOVA. The results were further processed with a MINITAB-17 software package to find the optimal conditions for inhibitor usage. Second order polynomial model was used for experimental data fitting. Optimum conditions for achieving the maximum corrosion inhibition efficiency are obtained from optimizing the above model and are found as follow: 39.66 °C temperature of acidic media, 38.29 ml/L inhibitor concentration and 2.95 h contact period. Results demonstrated that rate of corrosion was increased with temperature increasing & decreasing inhibitor concentration. It was concluded that the Taguchi design was adequately useful in the optimization of operating parameters and that RPP sufficiently inhibited the corrosion of steel at the range of variables studied.

A general procedure for isotopic (deuterium) labelling of non-steroidal antiinflammatory 2-arylpropionic acids

International Nuclear Information System (INIS)

Castell, J.V.; Martinez, L.A.; Universidad Politecnica de Valencia; Miranda, M.A.; Tarrega, Pilar

1994-01-01

Alkaline treatment of nonsteroidal antiinflammatory 2-arylpropionic acids in deuterium oxide led in all cases to isotopic exchange of the proton located at the α-position of the side chain. Monodeuteration was observed in the case of carprofen, ibuprofen, ketoprofen, fenoprofen, flurbiprofen and naproxen. Additional exchange of one or two protons of the heterocyclic ring occurred in indoprofen, suprofen and tiaprofenic acid. The isotopic labelling survived under the conditions required to perform in vitro photoallergic studies (photolysis in non-deuterated aqueous media). (Author)

A general procedure for isotopic (deuterium) labelling of non-steroidal antiinflammatory 2-arylpropionic acids

Energy Technology Data Exchange (ETDEWEB)

Castell, J.V. (Valencia Univ. Hospital (Spain). Centro de Investigacion); Martinez, L.A. (Valencia Univ. Hospital (Spain). Centro de Investigacion Universidad Politecnica de Valencia (Spain). Dept. de Quimica); Miranda, M.A.; Tarrega, Pilar (Universidad Politecnica de Valencia (Spain). Dept. de Quimica)

1994-01-01

Alkaline treatment of nonsteroidal antiinflammatory 2-arylpropionic acids in deuterium oxide led in all cases to isotopic exchange of the proton located at the [alpha]-position of the side chain. Monodeuteration was observed in the case of carprofen, ibuprofen, ketoprofen, fenoprofen, flurbiprofen and naproxen. Additional exchange of one or two protons of the heterocyclic ring occurred in indoprofen, suprofen and tiaprofenic acid. The isotopic labelling survived under the conditions required to perform in vitro photoallergic studies (photolysis in non-deuterated aqueous media). (Author).

Hydroxylamine electrochemistry at low-index single-crystal platinum electrodes in acidic media

NARCIS (Netherlands)

Rosca, V.; Beltramo, G.L.; Koper, M.T.M.

2004-01-01

The electrochemistry of hydroxylamine at low-index single-crystal platinum electrodes in acidic media has been studied by voltammetry and in-situ FTIRRAS. Hydroxylamine (HAM) reactivity at platinum is largely controlled by interaction of the other components of the solution or products of the HAM

Comparative photocatalytic study of two selected pesticide derivatives, indole-3-acetic acid and indole-3-butyric acid in aqueous suspensions of titanium dioxide

Energy Technology Data Exchange (ETDEWEB)

Qamar, M. [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Muneer, M. [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India)]. E-mail: cht12mm@amu.ac.in

2005-04-11

Heterogeneous photocatalysed degradation of two selected pesticide derivatives such as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) has been investigated in aqueous suspensions of titanium dioxide by monitoring the change in substrate concentration employing UV spectroscopic analysis technique and depletion in total organic carbon (TOC) content as a function of irradiation time. The degradation kinetics was studied under different conditions such as pH, types of TiO{sub 2,} substrate and catalyst concentration, and in the presence of electron acceptor such as hydrogen peroxide (H{sub 2}O{sub 2}) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 showed comparatively highest photocatalytics. The pesticide derivative, indole-3-acetic acid was found to degrade slightly faster than indole-3-butyric acid.

Detection of hypoxanthine, xanthine and uric acid in γ-irradiated aqueous solution of cytosine

International Nuclear Information System (INIS)

Kobayashi, Tsuya; Shirai, Kazuo

1979-01-01

The aqueous solution of cytosine of 3.6 x 10 -2 M was irradiated with gamma -ray (60 megarad) in nitrogen-saturated glass ampules, and freeze-dried, then the residue obtained was changed to trimethylsilylacid, and this was analyzed by paper chromatography, UV spectrometry, and/or gas-liquid chromatography. Hypoxanthine, xanthine and uric acid were detected in this solution, in addition to some other compounds already known to be produced by gamma -irradiation, e.g., TMS-uracil, TMS-6-hydroxyuracil and TMS-hypoxanthine. It was presumed that these compounds were formed by the recombination of the primary radiolytic products. Uric acid formation by this mechanism was confirmed by gamma -irradiation of the mixture that contained urea, and 5- and 6-hydroxyuracil. (Kaihara, S.)

Aqueous chlorination of mefenamic acid: kinetics, transformation by-products and ecotoxicity assessment.

Science.gov (United States)

Adira Wan Khalit, Wan Nor; Tay, Kheng Soo

2016-05-18

Mefenamic acid (Mfe) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the environment. This study investigated the kinetics and the transformation by-products of Mfe during aqueous chlorination. The potential ecotoxicity of the transformation by-products was also evaluated. In the kinetic study, the second-order rate constant (kapp) for the reaction between Mfe and free available chlorine (FAC) was determined at 25 ± 0.1 °C. The result indicated that the degradation of Mfe by FAC is highly pH-dependent. When the pH was increased from 6 to 8, it was found that the kapp for the reaction between Mfe and FAC was decreased from 16.44 to 4.4 M(-1) s(-1). Characterization of the transformation by-products formed during the chlorination of Mfe was carried out using liquid chromatography-quadrupole time-of-flight accurate mass spectrometry. Four major transformation by-products were identified. These transformation by-products were mainly formed through hydroxylation, chlorination and oxidation reactions. Ecotoxicity assessment revealed that transformation by-products, particularly monohydroxylated Mfe which is more toxic than Mfe, can be formed during aqueous chlorination.

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)

Synthesis of new annulated pyrano[2,3-d]pyrimidine derivatives using organo catalyst (DABCO in aqueous media

Directory of Open Access Journals (Sweden)

Ajmal R. Bhat

2017-01-01

Full Text Available A selective method for the synthesis of annulated pyrano[2,3-d]pyrimidines has been developed. It was shown that base catalysis is more efficient in this reaction, rather than acid catalysis as it is believed that 1,4-diazabicyclo[2.2.2]octane (DABCO is N-type base catalyst used for the synthesis of pyrano[2,3-d]pyramidine derivatives via one-pot three component condensation reactions of various aromatic aldehydes, active methylene compounds and barbituric acid in aqueous ethanol carried at normal temperature. The potential application of DABCO in organic synthesis increasing rapidly because of its reaction simplicity, less pollution, and minimum reaction time, high yields of the biological active products, uses less toxic solvents and low cost chemicals.

Acid-base properties of 2-phenethyldithiocarbamoylacetic acid, an antitumor agent

Science.gov (United States)

Novozhilova, N. E.; Kutina, N. N.; Petukhova, O. A.; Kharitonov, Yu. Ya.

2013-07-01

The acid-base properties of the 2-phenethyldithiocarbamoylacetic acid (PET) substance belonging to the class of isothiocyanates and capable of inhibiting the development of tumors on many experimental models were studied. The acidity and hydrolysis constants of the PET substance in ethanol, acetone, aqueous ethanol, and aqueous acetone solutions were determined from the data of potentiometric (pH-metric) titration of ethanol and acetone solutions of PET with aqueous solidum hydroxide at room temperature.

Features of obtaining malt with use of aqueous solutions of organic acids

Directory of Open Access Journals (Sweden)

O. Pivovarov

2017-12-01

Full Text Available Recently, the traditional formulations of essential food products are actively including malt – a valuable dietary product rich in extractives and hydrolytic enzymes, obtained by germination in artificially created conditions. Containing a full set of essential amino acids and a high saccharifying ability of malt, obtained from grain cereals, determines its wide use in the production of beer, alcohol, mono- and poly-malt extracts, bakery products, special types of flour, food additives, cereals, non-alcoholic beverages, lactic acid products and, in particular, in the production of natural coffee substitutes. However, the classical germination technology, which includes 2-3 days of soaking and 5-8 days of germination due to the considerable duration and laboriousness of the process, does not meet the requirements of modern technology and the constantly growing rates of industrial production, so this problem requires finding new and improving existing scientific and technical solutions. The features of malt production using organic acids of different concentrations are presented. The malt production technology has been analyzed and investigated. It includes washing, disinfection, air and water soaking of grains, germination and drying. The feature of the technology under investigation is using of aqueous solutions of butadiene, 3-pyridinecarboxylic acid and pteroylglutamic acid. The results of the inquiry of the effect of these organic acids on energy and the ability of germination of the grain are presented. The optimal values of concentrations of active substances in solutions are revealed. The influence of organic acids on the absorption of grain moisture has been investigated. It has been established that in comparison with the classical technology, the use of these acids as a growth stimulator can reduce the overall length of the reproduction process of the material from 1.5 to 2 times and increase the yield of flour grains in the batch of

Comparative Studies on Conventional and Ultrasound-Assisted Synthesis of Novel Homoallylic Alcohol Derivatives Linked to Sulfonyl Dibenzene Moiety in Aqueous Media

Directory of Open Access Journals (Sweden)

Mohamed F. Mady

2013-01-01

Full Text Available Novel homoallylic alcohols incorporating sulfone moieties were synthesized by the treatment of different carbonyl compounds with allylic bromides in aqueous media via sonochemical Barbier-type reaction conditions. Sulfonation of α-bromoketones with sodium benzenesulfinate in presence of CuI/2,6-lutidine rapidly gave β-keto-sulfones in good yields. In general, ultrasound irradiation offered the advantages of high yields, short reaction times, and simplicity compared to the conventional methods. The structures of all the compounds were confirmed by analytical and spectral data.

Inhibition of corrosion of mild steel in acid media by N ...

Indian Academy of Sciences (India)

Wintec

It acts as an anodic inhibitor. Thermodynamic and ... Thermo Electron Corporation Flash EA 1112 se- ries CHN analyser was used .... tiss et al 2001). In each acid media, maximum %IE was achieved at 11⋅494 × 10–4 M and a further increase in concentration did not cause any appreciable change in the performance of the ...

Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

Science.gov (United States)

Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

2016-09-01

There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe3+/Fe2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles' formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH.

Activation of Graphene Oxide with Hydrochloric Acid for Nitrate Removal from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Abolghasem Alighardashi

2017-11-01

Full Text Available Long-term drinking of nitrate-contaminated water poses a serious risk to human health. The present study explores the possibility of enhancing the adsorption capacity of graphene oxide via activation with hydrochloric acid for nitrate removal from aqueous solutions. Experiments were performed in a batch reactor in which such major factors as pH, reaction time, and concentrations of both graphene oxide (GO and activated graphene oxide (AGO were used as variables. Nitrate removal efficiency was investigated using the One-Way ANOVA statistical test and SPSS-16 software. The chemical composition and solid structure of the synthesized AGO were analyzed using FE-SEM coupled with energy dispersive spectrometry (EDS. The micropore volumes of the samples were determined using the BET and BJH. The predominant composition (52% of the synthesized AGO was C and its mean pore diameter was 26.896 nm. The maximum adsorption capacity of AGO was estimated at 3333.33 mg/g. Based on the results, the AGO nano-structure may be recomended as a new means for nitrate removal from aqueous solutions.

How Solid-Electrolyte Interphase Forms in Aqueous Electrolytes.

Science.gov (United States)

Suo, Liumin; Oh, Dahyun; Lin, Yuxiao; Zhuo, Zengqing; Borodin, Oleg; Gao, Tao; Wang, Fei; Kushima, Akihiro; Wang, Ziqiang; Kim, Ho-Cheol; Qi, Yue; Yang, Wanli; Pan, Feng; Li, Ju; Xu, Kang; Wang, Chunsheng

2017-12-27

Solid-electrolyte interphase (SEI) is the key component that enables all advanced electrochemical devices, the best representative of which is Li-ion battery (LIB). It kinetically stabilizes electrolytes at potentials far beyond their thermodynamic stability limits, so that cell reactions could proceed reversibly. Its ad hoc chemistry and formation mechanism has been a topic under intensive investigation since the first commercialization of LIB 25 years ago. Traditionally SEI can only be formed in nonaqueous electrolytes. However, recent efforts successfully transplanted this concept into aqueous media, leading to significant expansion in the electrochemical stability window of aqueous electrolytes from 1.23 V to beyond 4.0 V. This not only made it possible to construct a series of high voltage/energy density aqueous LIBs with unprecedented safety, but also brought high flexibility and even "open configurations" that have been hitherto unavailable for any LIB chemistries. While this new class of aqueous electrolytes has been successfully demonstrated to support diversified battery chemistries, the chemistry and formation mechanism of the key component, an aqueous SEI, has remained virtually unknown. In this work, combining various spectroscopic, electrochemical and computational techniques, we rigorously examined this new interphase, and comprehensively characterized its chemical composition, microstructure and stability in battery environment. A dynamic picture obtained reveals how a dense and protective interphase forms on anode surface under competitive decompositions of salt anion, dissolved ambient gases and water molecule. By establishing basic laws governing the successful formation of an aqueous SEI, the in-depth understanding presented in this work will assist the efforts in tailor-designing better interphases that enable more energetic chemistries operating farther away from equilibria in aqueous media.

Graphene oxide/MnO{sub 2} nanocomposite as destructive adsorbent of nerve-agent simulants in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Šťastný, Martin, E-mail: stastny@iic.cas.cz [Materials Chemistry Department, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Husinec-Řež (Czech Republic); Faculty of the Environment, J.E. Purkyně University in Ústí nad Labem, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic); Tolasz, Jakub; Štengl, Václav; Henych, Jiří [Materials Chemistry Department, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Husinec-Řež (Czech Republic); Žižka, David [Faculty of the Environment, J.E. Purkyně University in Ústí nad Labem, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

2017-08-01

Highlights: • Nanocomposite graphene oxide-birnessite-type MnO{sub 2} was synthesized by thermal hydrolysis. • New destructive sorbent for safe degradation of nerve-agent simulants. • 95% degradation activity for DMMP and TEP. - Abstract: Graphene oxide/MnO{sub 2} nanocomposite was prepared by thermal hydrolysis of potassium permanganate (KMnO{sub 4}) and 2-chloroacetamide aqueous solutions with graphene oxide (GO) suspension. The synthesized samples were characterized by specific surface area (BET) and porosity determination (BJH), X-ray Diffraction (XRD) and high-resolution electron microscopes (HRSEM, HRTEM). These nanocomposites were used in an experimental evaluation of their adsorption activity with nerve agent simulants dimethyl methyl phosphonate (DMMP) and triethyl phosphate (TEP) in aqueous media. The nanocomposites exhibited enhanced adsorptive degradation ability compared to pure manganese oxide (MnO{sub 2}) and GO. The GO amount in the nanocomposites affected their degradation activity substantially. The best adsorption efficiency was observed for samples with moderate GO amount. Three methods were used to observe the mechanism of the nerve-agent simulants deactivation: Gas chromatography with mass spectrometry (GC–MS), High-Performance Liquid Chromatography (HPLC) and in situ Infrared spectroscopy (FTIR). It was shown that the hydrolysis on the surface of prepared nanocomposites yields volatile primary alcohols (methanol and ethanol) as the main hydrolysis products.

Simulations and analysis of the Raman scattering and differential Raman scattering/Raman optical activity (ROA) spectra of amino acids, peptides and proteins in aqueous solution

DEFF Research Database (Denmark)

Jalkanen, Karl J.; Nieminen, R. M.; Bohr, Jakob

2000-01-01

The Raman and Raman optical activity (ROA) spectra of amino acids and small peptides in aqueous solution have been simulated by density functional theory and restricted Hartree/Fock methods. The treatment of the aqueous environment in treated in two ways. The water molecules in the first hydratio...

Removal of Acid Red 18 dye from Aqueous Solutions Using Nanoscale Zero-Valent Iron

Directory of Open Access Journals (Sweden)

Ahmad Reza Yari

2015-08-01

Full Text Available Background and Purpose:Organic dyes with a complex structure are often toxic, carcinogenic, mutagenic, non-biodegradation and stable in the environment and if released to the environment without treatment can endanger the environment and human health. The aim was to evaluate the performance nanoscalezero-valent iron (NZVI in the removal of dye acid red 18 (AR18 from aqueous solutions. Materials and Methods:This study was conducted at the laboratory scale. In this study, the removal efficiency of AR18 from a synthetic solution by NZVI was investigated. As well as the effect of solution pH, dye concentration, the concentration of NZVI and contact time in decolorization efficiency was investigated. Results:The results show that in pH = 3, contact time of 80 minutes, dye concentration of 25 mg/l and concentration of NZVI of 2 g/l, the removal efficiency was about 94%. Conclusion:According to the results of experiments, NZVI has high efficiency in removal of AR18 from aqueous solution.

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)

EXTRACTION AND SORPTION BENZOIC ACID FROM AQUEOUS SOLUTIONS OF POLYMERS BASED ON N-VINYLAMIDES

Directory of Open Access Journals (Sweden)

A. G. Savvina

2015-01-01

Full Text Available The widespread use of aromatic acids (benzoic acid, salicylic as preservatives necessitates their qualitative and quantitative determination in food. Effective and common way to separation and concentration of aromatic acids liquid extraction. Biphasic system of water-soluble polymers based on (poly-N-vinyl pyrrolidone, and poly-N-vinylcaprolactam satisfy the requirements of the extraction system. When sorption concentration improved definition of the metrological characteristics, comply with the requirements for sensitivity and selectivity definition appears possible, use of inexpensive and readily available analytical equipment. When studying the adsorption of benzoic acid used as a sorbent crosslinked polymer based on N-vinyl pyrrolidone, obtained by radical polymerisation of a functional monomer and crosslinker. In the extraction of benzoic acid to maximize the allocation of water and the organic phase of the polymer used salt solutions with concentrations close to saturation. Regardless of the nature of the anion salt is used as salting-out agent, aromatic acids sorption increases with the size of the cations. In the experiment the maximum recovery rate (80% benzoic acid obtained in the PVP (0.2 weight%. Ammonium sulphate. The dependence stepepni benzoic acid extraction from time sorption sorbent mass and the pH of the aqueous phase. To establish equilibrium in the system, for 20 minutes. The dependence of the degree of extraction of the acid pH indicates that the acid is extracted into the molecular form. The maximum adsorption is reached at pH 3,5, with its efficiency decreases symbatically reduce the amount of undissociated acid molecules in solution.

Effects of the Aqueous Extract from Tabebuia roseoalba and Phenolic Acids on Hyperuricemia and Inflammation

Directory of Open Access Journals (Sweden)

Zilma Schimith Ferraz-Filha

2017-01-01

Full Text Available Tabebuia species (Bignoniaceae have long been used in folk medicine as anti-inflammatory, antirheumatic, antimicrobial, and antitumor. The aim of this study was to investigate if aqueous extract from the leaves (AEL of Tabebuia roseoalba (Ridl. Sandwith, Bignoniaceae, and its constituents could be useful to decrease serum uric acid levels and restrain the gout inflammatory process. HPLC analysis identified caffeic acid and chlorogenic acid in AEL. Antihyperuricemic effects and inhibition of liver XOD (xanthine oxidoreductase by AEL and identified compounds were evaluated in hyperuricemic mice. Anti-inflammatory activity was evaluated on MSU (monosodium urate crystal-induced paw edema. In addition, AEL antioxidant activity in vitro was evaluated. AEL, caffeic, and chlorogenic acids were able to reduce serum uric acid levels in hyperuricemic mice probably through inhibition of liver xanthine oxidase activity and significantly decreased the paw edema induced by MSU crystals. AEL showed significant antioxidant activity in all evaluated assays. The results show that the AEL of Tabebuia roseoalba can be a promising agent for treatment for gout and inflammatory diseases. We suggest that caffeic and chlorogenic acids may be responsible for the activities demonstrated by the species.

Removal of phosphorus from agricultural wastewaters using adsorption media prepared from acid mine drainage sludge

Science.gov (United States)

Sibrell, Philip L.; Montgomery, Gary A.; Ritenour, Kelsey L.; Tucker, Travis W.

2009-01-01

Excess phosphorus in wastewaters promotes eutrophication in receiving waterways. A??cost-effective method for the removal of phosphorus from water would significantly reduce the impact of such wastewaters on the environment. Acid mine drainage sludge is a waste product produced by the neutralization of acid mine drainage, and consists mainly of the same metal hydroxides used in traditional wastewater treatment for the removal of phosphorus. In this paper, we describe a method for the drying and pelletization of acid mine drainage sludge that results in a particulate media, which we have termed Ferroxysorb, for the removal of phosphorus from wastewater in an efficient packed bed contactor. Adsorption capacities are high, and kinetics rapid, such that a contact time of less than 5 min is sufficient for removal of 60-90% of the phosphorus, depending on the feed concentration and time in service. In addition, the adsorption capacity of the Ferroxysorb media was increased dramatically by using two columns in an alternating sequence so that each sludge bed receives alternating rest and adsorption cycles. A stripping procedure based on treatment with dilute sodium hydroxide was also developed that allows for recovery of the P from the media, with the possibility of generating a marketable fertilizer product. These results indicate that acid mine drainage sludges - hitherto thought of as undesirable wastes - can be used to remove phosphorus from wastewater, thus offsetting a portion of acid mine drainage treatment costs while at the same time improving water quality in sensitive watersheds.

Near-infrared chemodosimetric probes based on heptamethine cyanine dyes for the “naked-eye” detection of cyanide in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Qiu, Dali [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China); Liu, Yijiang, E-mail: liuyijiang84@iccas.ac.cn [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China); Li, Mengnan [State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Hongbiao, E-mail: chhb606@163.com [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China); Li, Huaming [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China)

2017-05-15

Two simple chemodosimetric probes (P1 and P2) based on heptamethine cyanine dyes have been synthesized for highly sensitive and selective detection of cyanide anions (CN{sup −}) in aqueous media. The probes with an immobilized indolium salt as the specifically nucleophilic addition reaction site for CN{sup −} exhibit absorption bands in the near-infrared (NIR) region (650–850 nm). Upon the addition of CN{sup −}, the probes display a blue-shifted spectrum and result in apparent color change from green to brilliant yellow that can be easily observed by the naked eye even in the presence of other interfering anions such as F{sup −}, AcO{sup −}, Br{sup −}, NO{sub 2}{sup −}, Cl{sup −}, SO{sub 4}{sup 2−} and I{sup −}. There are good linear relationships between the fluorescence intensity of the probes and CN{sup −} concentrations, and the detection limits for P1 and P2 are estimated to be 0.017 μM and 0.2 μM, respectively. The sensing mechanism of the nucleophilic addition is confirmed by {sup 1}H NMR and mass spectroscopic analysis. In addition, the probe P2 is employed for cell imaging and the detection of CN{sup −} in living cells L929 is successfully realized. - Graphical abstract: Simple chemodosimetric probes based on heptamethine cyanine dye were synthesized and applied to detect CN{sup −} in aqueous media with colorimetric and fluorescent dual channel recognition.

An Efficient and Practical Process for Pd/Cu Cocatalyzed Homocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

Institute of Scientific and Technical Information of China (English)

ZHOU, Lei; ZHAN, Hai-Ying; LIU, Hai-Ling; JIANG, Huan-Feng

2007-01-01

A new process for the Pd/Cu co-catalyzed homocoupling reaction of terminal alkynes was developed. The reaction was carried out in aqueous media with sodium percarbonate as both a clean oxidant and a base. Meanwhile, a palladium complex immobilized on a synthetic PS-PEG400-PPh2 resin was used as the catalyst, which may be recovered by simple filtration and reused for several times with high activity.

f-Element Ion Chelation in Highly Basic Media

International Nuclear Information System (INIS)

Paine, R.T.

2000-01-01

A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelators for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

The role of acid anion on the inhibition of the acidic corrosion of steel by lupine extract

Energy Technology Data Exchange (ETDEWEB)

Abdel-Gaber, A.M. [Chemistry Department, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt)], E-mail: ashrafmoustafa@yahoo.com; Abd-El-Nabey, B.A.; Saadawy, M. [Chemistry Department, Faculty of Science, Alexandria University, Ibrahimia, P.O. Box 426, Alexandria 21321 (Egypt)

2009-05-15

The inhibitive effect of lupine (Lupinous albus L.) extract on the corrosion of steel in aqueous solution of 1 M sulphuric and 2 M hydrochloric acids was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization curves indicated that the lupine extract acts as a mixed-type inhibitor. EIS measurements showed that the dissolution process is under activation control. The inhibition efficiency of the extract obtained from impedance and polarization measurements was in a good agreement and was found to increase with increasing concentration of the extract. The obtained results showed that, the lupine extract could serve as an effective inhibitor for the corrosion of steel in acid media and the extract was more effective in case of hydrochloric acid. Theoretical fitting of the corrosion data to the kinetic-thermodynamic model was tested to show the nature of adsorption.

Assorted interactions of amino acids prevailing in aqueous vitamin C solutions probed by physicochemical and ab-initio contrivances

Science.gov (United States)

Das, Koyeli; Roy, Milan Chandra; Rajbanshi, Biplab; Roy, Mahendra Nath

2017-11-01

Qualitative and quantitative analysis of molecular interaction prevailing in tyrosine and tryptophan in aqueous solution of vitamin C have been probed by thermophysical properties. The apparent molar volume (ϕV), viscosity B-coefficient, molal refraction (RM) of tyrosine and tryptophan have been studied in aqueous vitamin C solutions at diverse temperatures via Masson equation which deduced solute-solvent and solute-solute interactions, respectively. Spectroscopic study along with physicochemical and computational techniques provides lots of interesting and highly significant insights of the model biological systems. The overall results established strong solute-solvent interactions between studied amino acids and vitamin C mixture in the ternary solutions.

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

Mineralization of 2,4-Dichlorophenoxyacetic Acid (2,4-D) and Mixtures of 2,4-D and 2,4,5-Trichlorophenoxyacetic Acid by Phanerochaete chrysosporium

Science.gov (United States)

Yadav, J. S.; Reddy, C. A.

1993-01-01

Evidence is presented for mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) in nutrient-rich media (high-nitrogen and malt extract media) by wild-type Phanerochaete chrysosporium and by a peroxidase-negative mutant of this organism. Mass balance analysis of [U-ring-14C]2,4-D mineralization in malt extract cultures showed 82.7% recovery of radioactivity. Of this, 38.6% was released as 14CO2 and 27.0, 11.2, and 5.9% were present in the aqueous, methylene chloride, and mycelial fractions, respectively. 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were simultaneously mineralized when presented as a mixture, and mutual inhibition of degradation was not observed. In contrast, a relatively higher rate of mineralization of 2,4-D and 2,4,5-T was observed when these compounds were tested as mixtures than when they were tested alone. PMID:16349039

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...

Enhanced defluoridation capacity from aqueous media via hydroxyapatite decorated with carbon nanotube

Science.gov (United States)

Tang, Qingzi; Duan, Tongdan; Li, Peng; Zhang, Ping; Wu, Daishe

2018-04-01

In this work, the potential of a novel carbon nanotube-doped hydroxyapatite composite (CNT-HAP) for fluoride removal was investigated. The synthesized CNT-HAP composite was systematically characterized by X-ray diffraction(XRD), Fourier Transform infrared spectroscopy(FTIR), scanning electron microscope (SEM) and Brunauer–Emmett–Teller(BET). Batch adsorption experiments were conducted to investigate the defluorination capacity of CNT-HAP. The CNT-HAP composite has a maximum adsorption capacity of 11.05 mg·g-1 for fluoride, and the isothermal adsorption data were fitted by the Freundlich model to calculate the thermodynamic parameters. Thermodynamic analysis implies that the adsorption of fluoride on CNT-HAP is a spontaneous process. Furthermore, the adsorption of fluoride follows pseudo-second-order model. The effects of solution pH, co-existing anions and reaction temperature on defluorination efficiency were examined to optimize the operation conditions for fluoride adsorption. It is found that the optimized pH value for fluoride removal by CNT-HAP composite is 6. In addition, among five common anions studied in this work, the presence of HCO3- and PO43- could considerably affect the fluoride removal by CNT-HPA in aqueous media. Finally, the underlying mechanism for the fluoride removal by CNT-HAP is analysed, and an anion exchange process is proposed.

Synthesis and self-assembling of responsive polysaccharide-based copolymers in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Marques, Nivia do N.; Balaban, Rosangela de C. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Halila, Sami; Borsali, Redouane, E-mail: borsali@cermav.cnrs.fr, E-mail: halila@cermav.cnrs.fr [Centre de Recherche sur les Macromolecules Vegetales (CERMAV), Grenoble (France)

2015-07-01

This work reports the synthesis and the thermoresponsive self-assembly behavior of carboxymethylcellulose-g-JeffamineM2070 and carboxymethylcellulose-g-JeffamineM600 copolymers in aqueous media. They were prepared through the grafting of two different types of amino-terminated poly(ethylene oxide-co-propylene oxide) chains onto the carboxylate groups of carboxymethylcellulose, by using water-soluble carbodiimide derivative and N-hydroxysuccinimide as coupling reagents. The grafting efficiency was confirmed by infrared and the degree of substitution by {sup 1}H NMR integrations. The salt effect on cloud point temperature was evaluated into different solvents (Milli-Q water, 0.5M NaCl, synthetic sea water (SSW) and 0.5M K{sub 2}CO{sub 3}) by UV-Vis and dynamic light scattering (DLS) measurements. Both copolymers showed lower cloud point temperature in 0.5M K2CO3 than in 0.5M NaCl and in SSW, which was attributed to the higher ionic strength for K{sub 2}CO{sub 3} combined to the ability of CO{sub 3}{sup 2-} to decrease polymer-water interactions. Copolymers chains displayed higher hydrodynamic radii than CMC precursor at 25 and 60 °C in saline solutions, and self-associations changed as a function of the environment and copolymer composition. (author)

Synthesis and self-assembling of responsive polysaccharide-based copolymers in aqueous media

International Nuclear Information System (INIS)

Marques, Nivia do N.; Balaban, Rosangela de C.; Halila, Sami; Borsali, Redouane

2015-01-01

This work reports the synthesis and the thermoresponsive self-assembly behavior of carboxymethylcellulose-g-JeffamineM2070 and carboxymethylcellulose-g-JeffamineM600 copolymers in aqueous media. They were prepared through the grafting of two different types of amino-terminated poly(ethylene oxide-co-propylene oxide) chains onto the carboxylate groups of carboxymethylcellulose, by using water-soluble carbodiimide derivative and N-hydroxysuccinimide as coupling reagents. The grafting efficiency was confirmed by infrared and the degree of substitution by "1H NMR integrations. The salt effect on cloud point temperature was evaluated into different solvents (Milli-Q water, 0.5M NaCl, synthetic sea water (SSW) and 0.5M K_2CO_3) by UV-Vis and dynamic light scattering (DLS) measurements. Both copolymers showed lower cloud point temperature in 0.5M K2CO3 than in 0.5M NaCl and in SSW, which was attributed to the higher ionic strength for K_2CO_3 combined to the ability of CO_3"2"- to decrease polymer-water interactions. Copolymers chains displayed higher hydrodynamic radii than CMC precursor at 25 and 60 °C in saline solutions, and self-associations changed as a function of the environment and copolymer composition. (author)

Interaction of model aryl- and alkyl-boronic acids and 1,2-diols in aqueous solution.

Science.gov (United States)

Marinaro, William A; Prankerd, Richard; Kinnari, Kaisa; Stella, Valentino J

2015-04-01

The goal of this work was to quantitate ester formation between alkyl and aryl boronic acids and vicinal-diols or 1,2-diols in aqueous solution. As used here, 1,2-diols includes polyols with one or more 1,2-diol pairs. Multiple techniques were used including apparent pKa shifts of the boronic acids using UV spectrophotometry (for aryl acids) and titration (for aryl and alkyl acids). Isothermal microcalorimetry was also used, with all reactions being enthalpically favored. For all the acids and 1,2-diols and the conditions studied, evidence only supported 1:1 ester formation. All the esters formed were found to be significantly more acidic, as Lewis acids, by 3-3.5 pKa units than the corresponding nonesterified boronic acid. The equilibrium constants for ester formation increased with increasing number of 1,2-diol pairs but stereochemistry may also play a role as sorbitol with five possible 1,2-diol pairs and five isomers (taking into account the stereochemistry of the alcohol groups) was twice as efficient at ester formation compared with mannitol, also with five possible 1,2-diol pairs but only three isomers. Alkyl boronic acids formed esters to a greater extent than aryl acids. Although some quantitative differences were seen between the various techniques used, rank ordering of the structure/reactivity was consistent. Formulation implications of ester formation between boronic acids and 1,2-diols are discussed. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Aqueous dissolution behaviour of Nd-bearing zirconolite in citric acid at 90 deg C

International Nuclear Information System (INIS)

McGlinn, P.J.; McLeod, T.; Aly, Z.; Zhang, Z.; Advocat, T.; Blackford, M.G.; Li, H.; Leturcq, G.

2004-01-01

The capacity for zirconolite to incorporate actinides, combined with a very high chemical durability, makes zirconolite-rich ceramics potential candidates for the containment of minor actinides from reprocessing of nuclear spent fuel. Our studies examine the chemical durability of sintered Nd-bearing zirconolite under simulated geological repository conditions, demonstrating the effect of citric acid (at varying concentrations), as an organic complexing agent, on the leaching behaviour of zirconolite under a low flow regime. The complexation limit of zirconolite at pH=5 in citrate media appears to be reached by 0.001 M citric acid concentration. Secondary phase development (titania and possibly titania-rich hydrolyzed species) was evident on the zirconolite leached in 0.0001 M citric acid, similar to that on zirconolite leached in water. (authors)

Potentiometric studies on ternary complexes involving some divalent transition metal ions, gallic acid and biologically abundant aliphatic dicarboxylic acids in aqueous solutions

Directory of Open Access Journals (Sweden)

Abdelatty Mohamed Radalla

2015-06-01

Full Text Available Formation of binary and ternary complexes of the divalent transition metal ions, Cu2+, Ni2+, Co2+ and Zn2+ with gallic acid and the biologically important aliphatic dicarboxylic acids (adipic, succinic, malic, malonic, maleic, tartaric and oxalic acids were investigated by means of the potentiometric technique at 25 °C and I = 0.10 mol dm−3 NaNO3. The acid-base properties of the ligands were investigated and discussed. The acidity constants of gallic acid and aliphatic dicarboxylic acids were determined and used for determining the stability constants of the binary and ternary complexes formed in the aqueous medium under the above experimental conditions. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes are inferred from the corresponding potentiometric pH-metric titration curves. The ternary complex formation was found to occur in a stepwise manner. The stability constants of these binary and ternary systems were calculated. The values of Δ log K, percentage of relative stabilization (%R.S. and log X were evaluated and discussed. The concentration distribution of the various complex species formed in solution was evaluated and discussed. The mode of chelation of ternary complexes formed was ascertained by conductivity measurements.

Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

Science.gov (United States)

Ryshetti, Suresh; Raghuram, Noothi; Rani, Emmadi Jayanthi; Tangeda, Savitha Jyostna

2016-04-01

Densities (ρ ) of (0.01 to 0.07) {mol}{\\cdot } {kg}^{-1} L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) {mol}{\\cdot } {kg}^{-1} solutions have been reported as a function of temperature at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure. The accurate density (ρ ) values are used to estimate the various parameters such as the apparent molar volume (V_{2,{\\upphi }}), the partial molar volume (V2^{∞}), the isobaric thermal expansion coefficient (α 2), the partial molar expansion (E2^{∞}), and Hepler's constant (partial 2V2^{∞}/partial T2)P. The Cosphere overlap model is used to understand the solute-solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler's constant (partial 2V2^{∞}/partial T2)_P is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.

Humic acid removal from aqueous solutions by peroxielectrocoagulation process

Directory of Open Access Journals (Sweden)

Ahmad Reza Yazdanbakhsh

2015-06-01

Full Text Available Background: Natural organic matter is the cause of many problems associated with water treatment such as the presence of disinfection by-products (DBPs and membrane fouling during water filtration. In this study, the performance of the peroxi-electrocoagulation process (PEP was investigated for the removal of humic acids (HAs from aqueous solutions. Methods: PEP was carried out for the removal of HA using a plexiglas reactor with a volume of 2 L and fitted with iron electrodes and a direct current supply (DC. Samples were taken at various amounts of pH (2-4, current density (1 and 2A/cm2, hydrogen peroxide (50-150 mg/L and reaction time (5-20 minutes and then filtered to remove sludge formed during reaction. Finally, the HA concentration was measured by UV absorbance at 254 nm (UV254. Results: Results indicated that increasing the concentration of H2O2 from 50 to 150 mg/L increased HA removal efficiency from 83% to 94.5%. The highest removal efficiency was observed at pH 3.0; by increasing the pH to the alkaline range, the efficiency of the process was reduced. It was found that HA removal efficiency was high in current density 1A/cm2. Increasing current density up to 1 A cm-2 caused a decrease in removal efficiency. Results of this study showed that under the optimum operating range for the process ([current density] = 1A/cm2, [hydrogen peroxide concentration] = 150 mg/L, [reaction time]= 20 minutes and [pH]= 3.0, HA removal efficiency reached 98%. Conclusion: It can be concluded that PEP has the potential to be utilized for cost-effective removal of HA from aqueous solutions.

Effectively designed molecularly imprinted polymers for selective isolation of the antidiabetic drug metformin and its transformation product guanylurea from aqueous media

Energy Technology Data Exchange (ETDEWEB)

Kyzas, George Z.; Nanaki, Stavroula G. [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Koltsakidou, Anastasia; Papageorgiou, Myrsini; Kechagia, Maria [Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Bikiaris, Dimitrios N. [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Lambropoulou, Dimitra A., E-mail: dlambro@chem.auth.gr [Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece)

2015-03-25

Highlights: • Preparation of novel MIPs with remarkable recognition properties. • Selective isolation and removal of metformin and guanylurea from aqueous media. • Detailed adsorbent characterization and adsorption studies. • Successful application of synthesized MIPs as dispersive SPE sorbents. • Estimation of expanded uncertainty following a bottom-up approach. - Abstract: In the present study, two novel molecularly imprinted polymers (MIPs) with remarkable recognition properties for metformin and its transformation product, guanylurea, have been prepared for their selective, enrichment, isolation and removal from aqueous media. The prepared adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and swelling experiments. The performance of the prepared MIPs was evaluated by various parameters including the influence of pH, contact time, temperature and initial compound concentration. The effects on the adsorption behavior of the removal process parameters were studied and the equilibrium data were fitted by the Langmuir and Freundlich models. Due to the imprinting effect, adsorption performance of MIPs was always superior to its corresponding NIP (non-imprinted polymer), with maximum adsorption capacity ∼80 mg g{sup −1} for both MIPs. Stability and reusability of the MIPs up to the 5th cycle meant that they could be applied repeatedly without losing substantial removal ability. In the next step, the prepared MIP nanoparticles were evaluated as sorbents in a dispersive solid phase extraction (D-SPE) configuration for selective enrichment and determination of metformin and guanylurea in different aqueous matrices. Under the working extraction conditions, the D-SPE method showed good linearity in the range of 50–1000 ng L{sup −1}, repeatability of the extractions (RSD 2.1–5.1%, n = 3), and low limits of detection (1.5–3.4 ng L{sup −1}). The expanded uncertainty of the data obtained

Oxidizing gel formulation for nuclear decontamination: rheological and acidic properties of the organic matrix and its ozonolysis

International Nuclear Information System (INIS)

Rouy, E.

2003-10-01

An acidic and oxidizing gel was formulated with a purely organic matrix, xanthan gum, at low concentrations (1 to 2 wt %). This polymer gel was investigated in various media (aqueous, acidic and ceric) by means of rheology: shear thinning behaviour, thixotropy, yield stress... Evidences of unexpected rheological properties in highly concentrated media show that xanthan is quite convenient for industrial projection of this type of gel on metallic walls in nuclear plants, notwithstanding its time-limited resistance to oxidation (about a few hours). Complexation mechanisms between ceric species and polar sites of the polymer led us to characterise acidic properties of our xanthan sample by potentiometric titration and 1 H NMR techniques. The matrix was finally treated by ozonolysis to suppress organic residues, as required to handle nuclear wastes. In acidic medium, ozonolysis of the gel was achieved successfully while in acidic and ceric medium this process showed limited efficiency, needing further investigation to be clarified. (author)

Estimation of solubility of organo-phosphorus extractants by P determination using molybdovanadophosphoric acid method

International Nuclear Information System (INIS)

Gill, J.S.; Kotekar, M.K.; Singh, H.

2005-01-01

Solvent extraction processes have been found to be suitable for uranium recovery from phosphoric acid. Various extractants like di-2-ethyl hexylphosphoric acid (D2EHPA), di-nonylphenyl phosphoric acid (DNPPA) and synergistic agents like tri-butyl phosphate (TBP), tri-octyl phosphine oxide (TOPO) have been used in liquid-liquid extraction of uranium from phosphoric acid. Contents of these organo-phosphorus compounds in aqueous raffinates need estimation for process requirements. Solubility of Tri-butyl phosphate (TBP) and Di-2-ethylhexyl phosphoric acid (D2EHPA) extractants have been determined in different media of water, oxalic acid (0.6M) and sulphuric acid (3.75M) solutions. These compounds were estimated by determining their phosphorus (P) contents employing molybdovanadophosphoric acid method, after digesting and solubalizing them in nitric and perchloric acid. (author)

Degradation of Acid Blue 25 in aqueous media using 1700kHz ultrasonic irradiation: ultrasound/Fe(II) and ultrasound/H(2)O(2) combinations.

Science.gov (United States)

Ghodbane, Houria; Hamdaoui, Oualid

2009-06-01

In this work, the sonolytic degradation of an anthraquinonic dye, C.I. Acid Blue 25 (AB25), in aqueous phase using high frequency ultrasound waves (1700kHz) for an acoustic power of 14W was investigated. The sonochemical efficiency of the reactor was evaluated by potassium iodide dosimeter, Fricke reaction and hydrogen peroxide production yield. The three investigated methods clearly show the production of oxidizing species during sonication and well reflect the sonochemical effects of high frequency ultrasonic irradiation. The effect of operational conditions such as the initial AB25 concentration, solution temperature and pH on the degradation of AB25 was studied. Additionally, the influence of addition of salts on the degradation of dye was examined. The rate of AB25 degradation was dependent on initial dye concentration, pH and temperature. Addition of salts increased the degradation of dye. Experiments conducted using distilled and natural waters demonstrated that the degradation was more efficient in the natural water compared to distilled water. To increase the efficiency of AB25 degradation, experiments combining ultrasound with Fe(II) or H(2)O(2) were conducted. Fe(II) induced the dissociation of ultrasonically produced hydrogen peroxide, leading to additional OH radicals which enhance the degradation of dye. The combination of ultrasound with hydrogen peroxide looks to be a promising option to increase the generation of free radicals. The concentration of hydrogen peroxide plays a crucial role in deciding the extent of enhancement obtained for the combined process. The results of the present work indicate that ultrasound/H(2)O(2) and ultrasound/Fe(II) processes are efficient for the degradation of AB25 in aqueous solutions by high frequency ultrasonic irradiation.

Separation of DR synthesized Ti-Mg Alloy by dissolution of waste by-products in acid media

CSIR Research Space (South Africa)

Mushove, T

2010-06-01

Full Text Available The objective of this work is to isolate synthesized Ti-Mg alloy powder through leaching out of MgO and any unreduced oxides of Titanium. Leaching media investigated are H2SO4, HCl and organic acids ascorbic acid/oxalic and L-cysteine /ascorbic...

Electrochemical detection of copper ions leached from CuO nanoparticles in saline buffers and biological media using a gold wire working electrode

Energy Technology Data Exchange (ETDEWEB)

Baldisserri, Carlo, E-mail: carlo.baldisserri@istec.cnr.it; Costa, Anna Luisa [ISTEC-CNR (Italy)

2016-04-15

We performed explorative cyclic voltammetry in phosphate-buffered saline buffers, Dulbecco’s modified Eagle’s medium (DMEM), and fetal bovine serum-added DMEM using Au wire as working electrode, both in the absence and in the presence of known nominal concentrations of Cu{sup 2+} ions or 15 nm CuO nanoparticles. Addition of either Cu{sup 2+} ions or aqueous suspension of CuO nanoparticles caused a single anodic peak to appear in the double-layer region of all three pristine media. The height of the anodic peak was found to increase in a monotonic fashion vs. Cu{sup 2+} concentration in Cu{sup 2+}-added media, and versus time since CuO addition in CuO-added media. Stepwise addition of glycine to Cu{sup 2+}-added phosphate-buffered saline buffer caused an increasing cathodic shift of the anodic peak accompanied by decreasing peak currents. Results indicate that preparing Cu{sup 2+}-free suspensions of CuO nanoparticles in such media is difficult, owing to the presence of leached copper ions. The implications on results of experiments in which CuO nanoparticle-added biological media are used as cell culture substrates are discussed. Literature data on the interactions between Cu{sup 2+} ions, dissolved carbon dioxide in aqueous CuO suspensions, and amino acids present in such media are compared to our results.

Electrochemical detection of copper ions leached from CuO nanoparticles in saline buffers and biological media using a gold wire working electrode

Science.gov (United States)

Baldisserri, Carlo; Costa, Anna Luisa

2016-04-01

We performed explorative cyclic voltammetry in phosphate-buffered saline buffers, Dulbecco's modified Eagle's medium (DMEM), and fetal bovine serum-added DMEM using Au wire as working electrode, both in the absence and in the presence of known nominal concentrations of Cu2+ ions or 15 nm CuO nanoparticles. Addition of either Cu2+ ions or aqueous suspension of CuO nanoparticles caused a single anodic peak to appear in the double-layer region of all three pristine media. The height of the anodic peak was found to increase in a monotonic fashion vs. Cu2+ concentration in Cu2+-added media, and versus time since CuO addition in CuO-added media. Stepwise addition of glycine to Cu2+-added phosphate-buffered saline buffer caused an increasing cathodic shift of the anodic peak accompanied by decreasing peak currents. Results indicate that preparing Cu2+-free suspensions of CuO nanoparticles in such media is difficult, owing to the presence of leached copper ions. The implications on results of experiments in which CuO nanoparticle-added biological media are used as cell culture substrates are discussed. Literature data on the interactions between Cu2+ ions, dissolved carbon dioxide in aqueous CuO suspensions, and amino acids present in such media are compared to our results.

Incorporating Pitzer equations in a new thermodynamic model for the prediction of acid gases solubility in aqueous alkanolamine solutions

NARCIS (Netherlands)

Alhseinat, E.; Mota Martinez, M.; Peters, C.J.; Banat, F.

2014-01-01

In gas sweetening, acid gases such as CO2 and/or H2S are usually removed by "chemical" absorption through aqueous amine solutions such as N-Methyldiethanolamine (MDEA) solution. Reliable prediction of equilibrium properties (vapor–liquid equilibrium and species distribution) is needed for a rigorous

Aqueous Dispersions of Silica Stabilized with Oleic Acid Obtained by Green Chemistry.

Science.gov (United States)

Nistor, Cristina Lavinia; Ianchis, Raluca; Ghiurea, Marius; Nicolae, Cristian-Andi; Spataru, Catalin-Ilie; Culita, Daniela Cristina; Pandele Cusu, Jeanina; Fruth, Victor; Oancea, Florin; Donescu, Dan

2016-01-05

The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA). The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles obtained by the sol-gel process of sodium silicate. The optimal molar ratio of OLA/OLANa can be ensured by a proper selection of OLA and respectively of sodium silicate concentration. The titration of sodium silicate with OLA revealed a stabilization phenomenon of silica/OLA vesicles and the dependence between their average size and reagent's molar ratio. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements emphasized the successful synthesis of silica nanoparticles starting from renewable materials, in mild condition of green chemistry. By grafting octadecyltrimethoxysilane on the initial silica particles, an increased interaction between silica particles and the OLA/OLANa complex was achieved. This interaction between the oleyl and octadecyl chains resulted in the formation of stable gel-like aqueous systems. Subsequently, olive oil and an oleophylic red dye were solubilized in these stable aqueous systems. This great dispersing capacity of oleosoluble compounds opens new perspectives for future green chemistry applications. After the removal of water and of the organic chains by thermal treatment, mesoporous silica was obtained.

Arenediazonium salts transformations in water media: Coming round to origins

OpenAIRE

Marina E. Trusova; Ksenia V. Kutonova; Victor V. Kurtukov; Victor D. Filimonov; Pavel S. Postnikov

2016-01-01

Aromatic diazonium salts belong to an important class of organic compounds. The chemistry of these compounds has been originally developed in aqueous media, but then chemists focused on new synthetic methods that utilize reactions of diazonium salts in organic solvents. However, according to the principles of green chemistry and resource-efficient technologies, the use of organic solvents should be avoided. This review summarizes new trends of diazonium chemistry in aqueous media that satisfy...

The effects of Α-tocopherol and ascorbic acid glucosides on radiation- and H2O2-induced decomposition of thymine in aqueous solution

International Nuclear Information System (INIS)

Brinkevich, S.D.; Lagutin, P.Yu.; Shadyro, O.I.

2008-01-01

The effects of ascorbic acid, ascorbic acid glycoside and α-tocopherol monoglycoside on radiation- and H 2 O 2 -induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, ascorbic acid glycoside was found to possess the most marked protecting properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of ascorbic acid and ascorbic acid glycoside, as well as properties of radical adducts formed during their interaction with OH radicals. (authors)

The stability of halloysite nanotubes in acidic and alkaline aqueous suspensions

International Nuclear Information System (INIS)

White, Rachel D; Bavykin, Dmitry V; Walsh, Frank C

2012-01-01

The long term stability of natural halloysite nanotubes was studied at room temperature (22 ± 2 °C) in pure water, acidic and basic aqueous suspensions. The structural and morphological transformations of nanotubes were studied by TEM, SEM, nitrogen adsorption, XRD Raman and FTIR spectroscopy accompanied by monitoring the concentration of dissolved Si(IV) and Al(III) in solution. It has been revealed that, in 1 mol dm −3 H 2 SO 4 solution, the dissolution of halloysite is initiated on the inner surface of nanotubes, leading to the formation of amorphous spheroidal nanoparticles of SiO 2 whereas, in 1 mol dm −3 NaOH solution, dissolution of the inner surface of nanotubes is accompanied by the formation of Al(OH) 3 nanosheets. (paper)

Humic acid transport in saturated porous media: influence of flow velocity and influent concentration.

Science.gov (United States)

Wei, Xiaorong; Shao, Mingan; Du, Lina; Horton, Robert

2014-12-01

Understanding the transport of humic acids (HAs) in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces. A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations. Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients, which resulted in an increased fraction of HA being retained in columns. Consequently, retardation factors were increased and the transport of HA through the columns was delayed. These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix. Accordingly, this attachment should be considered in studies of HA behavior in porous media. Copyright © 2014. Published by Elsevier B.V.

Zirconia sol-gel coatings deposited on 304 stainless steel for chemical protection in acid media

Energy Technology Data Exchange (ETDEWEB)

Luna, F Perdomo; Atik, M; Avaca, Luis A; Aegerter, M A [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica

1996-12-31

Zr O{sub 2} thin films were prepared by sol-gel method and using dip-coating technique for deposition on 304 austenitic stainless steel, from sonocatalyzed sols of zirconia alkoxide, isopropanol (Zr(O C{sub 3} H{sub 7})4/C{sub 3} H{sub 7} OH = 0.5), glacial acetic acid and water (C H{sub 3} CO OH/H{sub 2} O = 0.5). The films were dried at 40 deg C/15 min and thermally treated in the air with a linear variation of 5 deg C/min and two isothermal holdings at 400 deg C during 1 h and afterwards at 800 deg C during several periods of time (up to 20 h). The film thickness ranges between 0.6 and 0.8 {mu}m. Structure and morphology were studied by x-ray diffraction and scanning electron microscopy. The corrosion potential, the corrosion current density, the polarization resistance and the corrosion rate (mpy) in 1,0 N aqueous solution of H{sub 2} SO{sub 4} at room temperature were determined using potentiometric polarization curves with a scanning velocity of 1 mV/s. These films act as a blocking physical layer in the corrosion media and increase the substrate life time in a factor of 7 16 refs., 3 figs., 1 tab.

Hydrolysis of R7T7 nuclear waste glass in dilute media: mechanisms and rate as a function of pH

International Nuclear Information System (INIS)

Advocat, T.; Vernaz, E.; Charpentier, H.; Crovisier, J.L.; Ehret, G.

1990-01-01

R7T7 nuclear waste glass dissolution in highly dilute aqueous media under static conditions at 90 0 C occurs according to two different mechanisms depending on the solution acidity. In acid media (pH 4.8 and 5.5), preferential extraction of glass network modifiers results in the formation of an alkali metal-depleted surface region on which amorphous and crystallized (phosphate) compounds rich in transition elements precipitate. Steady-state dissolution conditions are not reached, as attested by variable normalized Si, B and Na mass losses. Glass dissolution is stoichiometric in basic media (pH 7 to 10): the strong bonds of the silicated network are broken at a rate that increases with the pH: the glass dissolution rate increases by a factor of 15 between pH 7 and 10. Under these conditions, alteration products at the glass/solution interface do not constitute a short-term kinetic barrier against the release of the major glass components