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Sample records for aqueous nitric acid

  1. Extraction of nitric acid, uranyl nitrate, and bismuth nitrate from aqueous nitric acid solutions with CMPO

    International Nuclear Information System (INIS)

    DOE sponsored development of the transuranium extraction (TRUEX) process for removing actinides from radioactive wastes. The solvent is a mixture of CMPO and TBP. Since the extraction characteristics of CMPO are not as well understood as those of TBP, the extraction of nitric acid, uranyl nitrate, and bismuth nitrate with CMPO (dissolved in n-dodecane) were studied. Results indicate that CMPO extracts nitric acid with a 1:1 stoichiometry; equilibrium constant is 2. 660±0.092 at 25 C, and extraction enthalpy is -5. 46±0.46 kcal/mol. Slope analysis indicates that uranyl nitrate extracts with a mixed equilibria of 1:1 and 2:1 stoichiometries in nearly equal proportion. Equil. constant of the 2: 1 extraction was 1.213 x 106±3.56 x 104 at 25 C; reaction enthalpy was -9.610±0.594 kcal/mol. Nitration complexation constant is 8.412±0.579, with an enthalpy of -10.72±1.87 kcal/mol. Bismuth nitrate also extracts with a mixed equilibria of (perhaps) 1:1 and 2:1 stoichiometries. A 2:1 extraction equilibrium and a nitrate complexation adequately model the data. Kinetics and enthalpies were also measured

  2. The photochemistry of neptunium in aqueous nitric acid solutions

    International Nuclear Information System (INIS)

    Photochemical reactions of Np(IV), (V) and (VI) have been investigated in nitric acid solutions using 254 and 300 nm excitation from standard mercury discharge lamps. Absorption spectrometry was used to monitor the concentrations of the various neptunium species in solution. In the absence of added reagents, all oxidation states of neptunium are converted to the pentavalent state. The effect of adding urea and mild reducing agents such as ethanol and hydrazine on the photolysis has also been examined. Quantum efficiencies for these reactions have been found to vary from 0.001 to 0.1, depending on the acid concentration, wavelength, and reaction conditions. (orig.)

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

    International Nuclear Information System (INIS)

    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 250C and 400C. The theoretical equilibrium data, obtained with the aid of a computer, are compared with the experimental results. (Author)

  4. Modified density equation for aqueous solution with plutonium(IV) and nitric acid

    International Nuclear Information System (INIS)

    In order to calculate criticality parameters for solution systems, the number densities of nuclides are needed and usually calculated by use of density equations. For the system of aqueous solution with Pu(IV) and nitric acid, Maimoni's equation based on Hofstetters' density data was often used, but its reliability was not thoroughly examined. The author, therefore, derived a modified density equation by regression analysis for Hofstetters' data, adding the authors' density data of aqueous solution with nitric acid. Comparison between both equations showed that the modified density equation gives more reliable densities in the wide range of temperature and concentration. (author)

  5. Radiation-thermal decomposition of nitric and acetic acids in the aqueous nitrate solution

    International Nuclear Information System (INIS)

    Kinetics of radiation, thermal and radiation-thermal decompositions of nitric and acetic acid mixture was investigated in aqueous sodium nitrate solution in homogeneous conditions as well as by interaction of solid phase as sand rock. Temperature dependences of rate of radiation, thermal and radiation-thermal decompositions of the acids were calculated using experimental data. Resulting solutions make possible the calculation of acid decomposition dynamics accounting conditions of underground radioactive waste disposals

  6. The distribution of acid, water, methanol, ethanol and acetone between mixed aqueous-organic nitric acid solutions of trilaurylammoniumnitrate in cyclohexane

    International Nuclear Information System (INIS)

    The distribution of acid, water, methanol, ethanol and acetone between mixed aqueous-organic nitric acid solutions and solutions of trilaurylammoniumnitrate in cyclohexane has been investigated. The distribution of acid rises with increasing concentrations of nitric acid, methanol, ethanol and acetone in the mixed aqueous-organic phase. The effect of the organic additives in increasing the distribution of the acid is methanol< ethanol< acetone. The concentration of nitric acid in the organic phase can be calculated by a formula similar to that describing the extraction from pure aqueous solutions. The distribution curves of water, methanol and ethanol resemble each other, all of them showing a minimum, when the distribution ratio is plotted versus the nitric acid concentration in the mixed aqueous-organic phase. The acetone distribution decreases steadily with increasing nitric acid concentration. The shape of the curves is briefly discussed. (T.G.)

  7. Extraction of nitric acid from aqueous media with OφD(iB)CMPO-n-dodecane

    International Nuclear Information System (INIS)

    A study of the extraction characteristics of nitric acid with octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide [OφD(iB)CMPO or, simply, CMPO] was conducted. In the experimental program, CMPO was dissolved in n-dodecane to produce the organic extracting medium. The objectives of the project were to infer extraction stoichiometry and to estimate equilibrium constants for the extraction of nitric acid with the CMPO extractant. Experiments were performed over a limited range of concentrations to avoid conditions favoring formation of a third phase. Aqueous nitric acid concentrations were limited to 0.30 M at 25 C, 1.0 M at 40 C, and 3.0 M at 50 C. The data indicate that CMPO extracts nitric acid with a 1:1 stoichiometry. The value of the equilibrium constant is estimated at 2.66 ± 0.09 at 25 C. The enthalpy of the extraction is estimated to be -5.46 ± 0.46 kcal/mol

  8. Zirconium distribution between two phases: di-2-ethyl-hexyl phosphoric acid diluted in dodecane and aqueous phase of nitric acid

    International Nuclear Information System (INIS)

    Zirconium extraction by di-2-ethyl-hexyl phosphoric acid, from 0.5 to 10M nitric acid solutions is measured. The mechanism is independent of the acidity of the aqueous phase; a carbonic complex of zirconium nitrate is extracted. From a concentration 6M HNO3, an important extraction of nitric acid is noted. Consequences are brought out

  9. 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...... hydrolysis are compared. The effects of temperature, acid concentration, composition of organic phase (for sulfuric acid), and pressure (for nitric acid) on the effectiveness of pretreatment were analyzed. It is shown that the use of organosolv with 0.5% sulfuric acid allows us to increase the reactivity of...

  10. The redox chemistry of neptunium in γ-irradiated aqueous nitric acid in the presence of an organic phase

    International Nuclear Information System (INIS)

    The radiolytic changes in oxidation state for solutions of initially Np(V) and/or Np(VI) were investigated by gamma-irradiation in conjunction with UV/Vis spectroscopy of the aqueous phase. Samples were irradiated in varying concentrations of nitric acid, and with or without the presence of 30 % TBP in dodecane. At short irradiation times Np(V) was oxidized to Np(VI), even in the presence of the organic phase. Upon the radiolytic production of sufficient amounts of nitrous acid, reduction of Np(VI) to Np(V) occurred in both phases. This was accompanied by stripping of the previously extracted Np(VI). Nitric acid concentrations of 6 M mitigated this reduction. (author)

  11. Chromatography of 49 metal ions on stannic antimonate papers in dimethylsulfoxide: nitric acid systems and aqueous nitric acid systems

    International Nuclear Information System (INIS)

    Chromatographic separations of 49 metal ions on stannic antimonate papers have been performed using mixed solvent systems containing DMSO. Aqueous HNO3 systems have also been used. The utility of the papers has been demonstrated by achieving various difficult separations. Some of the important separations (R/sub f/ values given in parentheses) are: Cs+(0.20)-K+(0.30) and Sm3+(0.00)-Pr3+(0.72) in pure DMSO; Nb5+(0.14)-VO2+(0.95) in DMSO-6M HNO3 (1:1); Ti4+(0.00)-VO2(0.97) in DMSO-0.5M HNO3 (1:1); and Ba2+(0.06)-K+(0.52)-Sr2+(0.95), Ba2+(0.04)-Cs+(0.41)-Mg2+(0.93), and Ca2+(0.10)-Sr2+(0.94) in DMSO-0.1M HNO3 (1:1). The time of development in each case is two hours. A discussion is presented on the dependence of Ri, log R/sub f/, and R/sub M/ on pH of the solvent to understand the mechanism of the movement of metal ions on papers impregnated with inorganic materials. (U.S.)

  12. 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)

    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 (TNO3). 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)

  13. Distribution coefficient correlations for nitric acid, U(VI) and Pu(IV) in two-phase system with aqueous nitric acid and 30% tri-n-butylphosphate solutions

    International Nuclear Information System (INIS)

    Distribution coefficient correlations are obtained for nitric acid, U(VI) and Pu(IV) extracted with 30% tri-n-butylphosphate (TBP) diluted by n-dodecane from aqueous nitric acid solutions. The correlation functions are described as a mathematical model that takes account of activity coefficients expressed by a function of ionic strength. The correlations include the temperature effect on distribution coefficient, and works successfully for the experimental distribution coefficients in the literature within the temperature range of 10 to 70degC. The concentrations of nitric acid, U(VI) and Pu(IV) in a multi-stage extraction experiment previously reported have been simulated well with the new distribution correlations at room and elevated temperatures. (author)

  14. Spectrophotometric determination of Rare Earth Elements in aqueous nitric acid solutions for process control.

    Science.gov (United States)

    Rodionova, Oxana Ye; Tikhomirova, Tatyana I; Pomerantsev, Alexey L

    2015-04-15

    Noninvasive analytical control is of special interest for the complicated and hazardous production processes. On-line monitoring provides a unique opportunity to determine critical concentrations rapidly and without serious risks to operating personnel and the environment. Models for quantitative determination of concentrations of Rare Earth Elements in complex mixtures in nitric acid serve for these purposes. Here, the feasibility of simultaneous determination of cerium, praseodymium, and neodymium using the whole UV-vis spectroscopic range, together with chemometric data processing, is studied. The predictability of two chemometric techniques, partial least squares regression and correlation constrained multivariate curve resolution-alternating least squares are compared. Models' performances are analyzed in out-of-control cases. PMID:25818140

  15. Influence of external magnetic field on the etching of a steel ball in an aqueous solution of nitric acid

    International Nuclear Information System (INIS)

    The effect of change of shape of a steel ball was revealed as a result of its etching in an aqueous solution of nitric acid under influence of an external magnetic field. The elongation of a ferromagnetic ball was observed along the direction of an external magnetic field while etching took place uniformly in all the directions without magnetic field application. The steel ball etching in a magnetic field is characterized by formation of three cylindrically symmetric regions with different etching rates and surface structures, divided from each other by clear borders (namely, the pole, equator and transition regions are formed). The non-monotone dependences of etching rate, surface structure of a sample and sample shape after etching on an external magnetic field are observed.

  16. Ruthenium nitrosyl complexes in nitric acid solutions

    International Nuclear Information System (INIS)

    Nine nitrosyl ruthenium complexes have been separated and identified in aqueous solutions of nitric acid. The separation method was low temperature, gradient elution, reverse phase partition chromatography using tri-n-butyl phosphate on a kiesel gel 60 support using 106Ru labelled complexes in the nitric acid phase. The identification of the complexes was deduced from the relationships between the products of aquation and nitration and paper chromatography using both methyl-iso-propyl ketone and nitric acid-acetone elutions. The proportion of each complex at equilibrium in various concentrations of nitric acid have been measured. The rates of nitration in 10 M nitric acid, and of aquation in 0.45 M nitric acid have been determined at 00C. (author)

  17. Diglycolamic acid functionalized PAMAM-SDB chelating resin for removal of Th(IV) from aqueous and nitric acid medium

    International Nuclear Information System (INIS)

    Removal of radionuclides based on solid phase extraction (SPE) also known as solid-liquid extraction is developed considerably in the last few decades due to their simplicity, rapidity, easy operation and cost effectiveness. Various types of sorbents such as organic, inorganic, bio-sorbent, composites and carbon based material have been developed for the recovery of radionuclides. Among the solid sorbents, chelating resins are being increasingly used due to their high adsorption capacity and selectivity. The chelating resins are prepared either by impregnating or grafting the chelating agents on solid substrate. Generally, the adsorption efficiency depends on the type of chelating agent and to some extent on the size and physiochemical properties of the resin. Recovery of actinides from aqueous waste using chelating agent containing >P=O, >C=O or other functional groups of desired basicity and stereochemistry have been extensively studied. Removal of thorium from aqueous solution using diglycolamic acid (DGA) functionalized poly(amido)amine (PAMAM) dendron-styrene divinyl benzene (SDB) chelating resin is presented in this paper

  18. Determination of Nitric Acid in Aqueous Solution of Uranium and Plutonium Purification Cycle by Near Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI; Ding-ming; WANG; Lin; ZHANG; Li-hua; GONG; Yan-ping; MU; Ling; WU; Ji-zong

    2012-01-01

    <正>The concentration of nitric acid interfered with the distribution of uranium and plutonium in nuclear fuel reprocessing process. So, in the reprocessing process control analysis, the determination of the free acid plays an important role. Traditional laboratory analytical method of free acid needs large size sample and is time-consuming. Hence, development of fast analytical method for free acid has important significance for the reprocessing process control analysis. Near-infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool and used in various fields, it’s seldom, however, used in spent

  19. Extraction of scandium from various media with triisoamyl phosphate. Communication 1. extraction of Sc and impurity metals from aqueous nitric acid solutions

    International Nuclear Information System (INIS)

    The main features of extraction of Sc from aqueous nitric acid solutions with triisoamyl phosphate (TIAP) were studied. It was shown that Sc passes into the organic phase in the form of Sc(NO3)3·3TIAP. The extraction isotherms of Sc from its aqueous HNO3 solutions and from those containing salting-out agents (LiNO3, NH4NO3) with TIAP in dodecane were obtained. The distribution factor of Sc was studied in relation to the concentrations of TIAP, salting-out agent, and HNO3. The extraction of Sc and impurity metals (Zr, Th, REE) with TIAP was studied using a tracer technique at widely varied HNO3 concentration in the aqueous phase. The separation factors of Sc from impurity metals were determined

  20. Effect of ultrasonic frequency on H2O2 sonochemical formation rate in aqueous nitric acid solutions in the presence of oxygen.

    Science.gov (United States)

    Dalodière, Elodie; Virot, Matthieu; Moisy, Philippe; Nikitenko, Sergey I

    2016-03-01

    The influence of the ultrasonic frequency (20 kHz, 207 kHz, and 615 kHz) towards the formation kinetics of H2O2 under Ar and Ar/(20 vol.%)O2 atmospheres was evaluated in pure water and aqueous nitric solutions. Results obtained at low frequency ultrasound demonstrate that hydrogen peroxide formation is enhanced under an Ar/O2 gas mixture whatever the sonicated medium. Nevertheless, H2O2 yields are higher in aqueous nitric solutions whatever the nature of the saturating gas. These observations are consistent at high frequency ultrasound under Ar gas notwithstanding higher yields for H2O2. Surprisingly, an inverse tendency is observed for high frequency sonolysis carried out under an Ar/O2 atmosphere: higher yields of H2O2 are measured in pure water. Further studies in the presence of pure Ar revealed a more important decomposition of nitric acid under high frequency ultrasound leading to higher yields of both HNO2 in the liquid phase and NO in the gas phase. In the presence of Ar/O2 mixture, the intrabubble oxidation of NO causes cavitation bubble depletion in O2 leading to the drop of H2O2 yield. On the other hand, it was found that for Ar/(20 vol.%)O2 mixture there is no influence of oxygen on HNO2 yield whatever the ultrasonic frequency; this is most likely explained by two processes: (i) HNO2 formation results from nitrate-ion thermolysis in the liquid reaction zone surrounding the cavitation bubble, and (ii) effective intrabubble oxidation of NOx species by oxygen to nitrate-ion. PMID:26584999

  1. REACT-Mod: a mathematical model for transient calculation of chemical reactions with U-Pu-Np-Tc in the aqueous nitric acid solution

    International Nuclear Information System (INIS)

    A computer code REACT-Mod which simulates various chemical reactions in an aqueous nitric acid solution involving uranium, plutonium, neptunium, technetium etc. e.g., redox, radiolytic and disproportionation reactions of 68, was developed based on the kinetics model. The numerical solution method adopted in the code are two, a kinetics model totally based on the rate law of which differential equations are solved by the modified Porsing method, and a two-step model based on both the rate law and equilibrium law. Only the former treats 27 radiolytic reactions. The latter is beneficially used to have a quick and approximate result by economical computation. The present report aims not only to explain the concept, chemical reactions treated and characteristics of the model but also to provide details of the program for users of the REACT-Mod code. (author)

  2. Tri-iso-amyl phosphate: a new indigenous extractant for U(VI) and Pu(IV) from aqueous nitric acid solutions

    International Nuclear Information System (INIS)

    The extraction behaviour of U(VI), Pu(IV) and some long lived fission products into dodecane from aqueous HNO3 solutions with an indigenously prepared extractant, namely tri-iso-amyl phosphate (TAP) was examined systematically. The distribution data revealed a quantitative extraction of both U(VI) and Pu(IV) from moderate nitric acidities in the range 2-7 M. Slope analyses proved predominant formation of the disolvated organic phase complex of the type UO2(NO3)2.2TAP and Pu(NO3)4.2TAP with U(VI) and Pu(IV), respectively. On the contrary, the extraction of fission product contaminants was almost negligible indicating its potential application in actinide partitioning. (author). 3 refs., 2 tabs

  3. Studies on size variation of U(IV) colloids formed in aqueous nitric acid solutions. Contributed Paper RD-06

    International Nuclear Information System (INIS)

    Tetravalent Uranium readily undergoes hydrolysis even in highly acidic aqueous solutions. In the present work, solutions with concentration and pH ranges of 0.4 - 19 mM (total U) and 1- 4 respectively were investigated by light scattering technique with special emphasis on polymerization leading to colloid formation. Size variation of colloids formed at different pH was monitored. The results clearly indicate that the concentration has significant effect on particle size as well as stability of colloids. With increasing concentration, the size of colloids formed is smaller due to more crystalline nature of the colloids. Stability of colloids formed at lower concentration is greater than that of colloids formed at higher concentration. The results of this work are a clear indication that U(IV) hydrolysis does not differ from that of Pu(IV). (author)

  4. 49 CFR 173.158 - Nitric acid.

    Science.gov (United States)

    2010-10-01

    ... 2.5 L (0.66 gallon) capacity each. (f) Nitric acid of 70 percent or less concentration, when offered... 49 Transportation 2 2010-10-01 2010-10-01 false Nitric acid. 173.158 Section 173.158... Nitric acid. (a) Nitric acid exceeding 40 percent concentration may not be packaged with any...

  5. Nitric Acid Poisoning: Case Report

    International Nuclear Information System (INIS)

    Nitric acid (HNO3) is a corrosive fluid that, when in contact with reducing agents, generates nitrogen oxides that are responsible for inhalation poisoning. We present two cases of poisoning from nitric acid gas inhalation resulting from occupational exposure. Imaging findings were similar in both cases, consistent with adult respiratory distress syndrome (ARDS): bilaterally diffuse alveolar opacities on the chest X-ray and a cobblestone pattern on computed tomography (CT).one of the patients died while the other evolved satisfactorily after treatment with n-acetyl cysteine and mechanical ventilation. The diagnosis of nitric acid poisoning was made on the basis of the history of exposure and the way in which the radiological findings evolved.

  6. Corrosion studies in fuel element reprocessing environments containing nitric acid

    International Nuclear Information System (INIS)

    Nitric acid is universally used in aqueous fuel element reprocessing plants; however, in the processing scheme being developed by the Consolidated Fuel Reprocessing Program, some of the equipment will be exposed to nitric acid under conditions not previously encountered in fuel element reprocessing plants. A previous report presented corrosion data obtained in hyperazeotropic nitric acid and in concentrated magnesium nitrate solutions used in its preparation. The results presented in this report are concerned with the following: (1) corrosion of titanium in nitric acid; (2) corrosion of nickel-base alloys in a nitric acid-hydrofluoric acid solution; (3) the formation of Cr(VI), which enhances corrosion, in nitric acid solutions; and (4) corrosion of mechanical pipe connectors in nitric acid. The results show that the corrosion rate of titanium increased with the refreshment rate of boiling nitric acid, but the effect diminished rapidly as the temperature decreased. The addition of iodic acid inhibited attack. Also, up to 200 ppM of fluoride in 70% HNO3 had no major effect on the corrosion of either titanium or tantalum. In boiling 8 M HNO3-0.05 M HF, Inconel 671 was more resistant than Inconel 690, but both alloys experienced end-grain attack. In the case of Inconel 671, heat treatment was very important; annealed and quenched material was much more resistant than furnace-cooled material.The rate of oxidation of Cr(III) to Cr(VI) increased significantly as the nitric acid concentration increased, and certain forms of ruthenium in the solution seemed to accelerate the rate of formation. Mechanical connectors of T-304L stainless steel experienced end-grain attack on the exposed pipe ends, and seal rings of both stainless steel and a titanium alloy (6% Al-4% V) underwent heavy attack in boiling 8 M HNO3

  7. Decomposition of molybdenite products with nitric acid

    International Nuclear Information System (INIS)

    The problems of development abroad of hydrometallurgic methods of opening molybdenum concentrates using nitric acid are considered. Several variants of the process are developed, they are the two-stage decomposition by stoichiometrically necessary amount of nitric acid, single-stage decomposition in the avtoclave using nitric acid and oxigen as oxidizers; decomposition using circulatina nitro-sulfuric solution containing molybdenum. The advantages and disadvantages of new methods are presented

  8. Decomposition of molybdenite products with nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Nikitina, L.S.

    1983-04-01

    The problems of development abroad of hydrometallurgic methods of opening molybdenum concentrates using nitric acid are considered. Several variants of the process are developed, they are the two-stage decomposition by stoichiometrically necessary amount of nitric acid, single-stage decomposition in the autoclave using nitric acid and oxigen as oxidizers; decomposition using circulatina nitro-sulfuric solution containing molybdenum. The advantages and disadvantages of new methods are presented.

  9. Actinide and lanthanide extraction from nitric acid solutions by flotation

    International Nuclear Information System (INIS)

    Flotation of thorium, plutonium(IV), uranium(VI) and gadolinium from aqueous nitric acid solutions (HNO3) was investigated using lauryl phosphoric acid (LPA) as a SAS-collector. It is established that the extent of removal of the metal ions increases with the amount of LPA introduced, regardless of the solution acidity. It is shown that in principle ∼ 100% extraction of plutonium(IV) and thorium by flotation is possible regardless of the acidity of aqueous solutions. Ca(NO3)2 added to the system does not significantly affect the flotation extraction of thorium. (author) 14 refs.; 5 figs

  10. Nitrogen isotope exchange in between nitric oxide and nitric acid

    International Nuclear Information System (INIS)

    The exchange rate law experimentally observed for 15 N/14 N exchange in NO - HNO3 system at low nitric acid concentration, both at atmospheric pressure and at low pressure of NO: R k[H+][NO3-][HNO2], is identical with the rate law for the reaction between NO and HNO3, when HNO2 is formed.The rate of nitrogen isotope exchange between NO and HNO3 has been measured as a function of nitric acid concentration of 1.5 4 M.l-1. The exchange rate law is shown to be R k[HNO3]2[N2O3] and the measured activation energy is E = 67.78 kJ.M-1. It is concluded that N2O3 participates in 15 N/14 N exchange between NO and HNO3 at nitric acid concentration higher than 1.5 M.l-1. The rate of the same isotope exchange in NO - HNO3 system has been also measured as a function of nitric oxide pressure 0.1 0.4 M.Pa for 1 and 2 M.l-1 HNO3. It is demonstrated that 15 N/14 N exchange in this system has a linear dependence on NO pressure as indicated by rate measurements at different NO partial pressures and constant overall pressure, by adding helium in reactor. Using the rate law presented above the nitrogen isotope exchange rate for nitric acid concentration 1.5 10 M.l-1 were calculated. Nitrogen isotope exchange between nitric oxide and concentrated nitric acid with a single stage separation factor = 1.055, for 10 M.l-1 nitric acid, at 25 deg. C, provides the bases for 15 N separation process that is most widely used at the present time, i.e. the method of Spindel and Taylor. In order to know what happens in 15N separation at higher pressure, when the isotopic transport is improved, a stainless steel laboratory experimental plant with a 1000 mm long and 18 mm i.d. column, packed with triangular wire springs of 1.8 x 1.8 x 0.2 mm, was utilised. At 1.5 atm (absolute) and 2.36 ml.cm-2.min-1 flow rate, HETP was 7% smaller than at atmospheric pressure and 1.5 times smaller flow rate. The operation of 15 N separation plant at 1.8 atm (absolute), instead atmospheric pressure, will permit doubling

  11. Separation of ruthenium from nitric acid solutions using carbon tetrachloride

    International Nuclear Information System (INIS)

    The noble metal, ruthenium is one of the major fission product elements produced with high fission yield, mainly in for breeder reactors using 239Pu fuels. In the aqueous reprocessing of spent fuels for the recovery of U and Pu by PUREX process ruthenium interferes in the solvent extraction stage. In the treatment of high level liquid waste for its disposal, oxides of Ru are formed, which contaminate the surrounding environment owing to their high vapour pressure. Hence, it is desirable to separate from the waste solution prior to its processing for disposal. A simple and feasible method has been employed in the present work for the separation and recovery of ruthenium from aqueous nitric acid medium using ammonium ceric nitrate (ACN) and carbon tetrachloride (CCl4). The efficiency in the separation of Ru was investigated under various experimental conditions such as acidity and ageing effect. Separation efficiency was observed to decrease with increasing nitric acid concentration. Maximum separation was achieved at 1 M nitric acid. Further studies were carried out to investigate the effect of ageing on the separation efficiency ruthenium. With increase in time, separation percentage of ruthenium was decreasing in all concentrations of nitric acid studied. (author)

  12. Research on the Stability of Diethyl Hydroxylamine in Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By the means of the comparison of the extraction of PU(Ⅲ,Ⅳ) and plutonium in the aqueous Phasecontaining salting-free agent, the stability of diethyl hydroxylamine in nitric acid medium is investigated.

  13. Electrochemical Behavior of Aluminum in Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    CHEN; Hui; ZHU; Li-yang; LIN; Ru-shan; TAN; Hong-bin; HE; Hui

    2013-01-01

    Aluminum is one of cladding materials for nuclear fuel,it is important to investigate the electrolytic dissolution of aluminum in nitric acid.The electrochemical impedance spectroscopy,polarization curve and cyclic voltammetry cure of anodic aluminum electrode in nitric acid under various conditions were collected(Fig.1).It turns out,under steady state,the thickness of the passivated film of aluminum

  14. Modelling the liquid-liquid extraction of nitric acid and lanthanide nitrates by tributylphosphate. Study of the influence of the aqueous phase composition on the selectivity of rare earth separation

    International Nuclear Information System (INIS)

    This research thesis reports the application of advances in the modelling of liquid-liquid extraction to a quantitative processing of the selectivity of separations. It is here applied to the extraction-based separation of lanthanide nitrates by using the tributylphosphate (TBP) in nitric environment as this system is interesting for industrial applications in hydro-metallurgy of rare earths as well as in the processing of irradiated nuclear fuels. Experimental data are acquired and then used in the Mikulin-Sergievskii-Dannus model. Complete modelling is thus obtained which allowed the complex problem of extraction of nitric acid and of lanthanide to be addressed, and the existence of a hybrid solvate to be supported. A mathematical expression of the separation factor of two lanthanides is proposed and used to highlight its influencing parameters, i.e. water activity in the aqueous phase, and the rate of the effective extraction constants of the two elements to be separated. Experimental observations are thus interpreted. The selection of optimal separation conditions is thus justified, and, in some cases, the system selectivity can be predicted

  15. Extraction of metal nitrates and nitric acid

    International Nuclear Information System (INIS)

    The effects of the extraction of nitric acid with nondiluted dialkylphosphoric acids have been studied. The investigation used the physical-chemical method allowing to determine the compositions of compounds in organic phase and to describe the equilibrium in a wide concentration range of distributed chemical. The solvate compositions determined from the dependence of the effective nitric acid distribution constant in extraction with nondiluted dibutyl (DBPA) and di-2-ethyl-hexylphosphoric (D2EHPA) acids on the function of equilibrium water activity agree with different reported physical-chemical methods of research. Thermodynamic distribution and extraction constants have been calculated and tabulated for the formation and organic phase of dissociated and nondissociated disolvates, as well as monosolvates of nitric acid

  16. Basic physical and chemical properties of ReillexTM-HPQ anion exchange resin and its sorption behavior of halides in aqueous nitric acid solution

    International Nuclear Information System (INIS)

    The ReillexTM-HPQ anion exchange resin has a good potential toward the pretreatment of liquid nuclear wastes. In this work, a short procedure was devised to convert 99.997% of the resin from its chloride form to the nitrate form as a foundation of all quantitative measurements. It is determined that the resin can be dried to a constant mass at 60 degree C in 28 hours and the electrostatic effect during weighings can hence be eliminated. The weight ratio between resins dried at 110 degree C and 60 degree C is 0.927±0.005 (one standard deviation). The resin has an apparent pKa of 3.36±0.05. The sorption capacity from primarily the weakly basic ionogenic sites (RNH+) is 1.08±0.04 meq/g for resins dried at 60 degree C. In highly basic solutions, the resin became unstable and started to release a substantial amount of methanol. In nitric acid solutions, the selectivity sequence of halide ions versus nitrate and pertechnetate ions is: TcO4- > I- > NO3- > Br- > Cl- > F-. The HPQ resin showed no sorption of fluoride ions. Although the sorption of chloride ions is also low the data can be modeled well by an equation similar to the Freundlich isotherm at a pH range between 2.0 and 3.0. Both bromide and iodide ions showed moderate sorptions when [HNO3] = 1.00 M and the sorption data can be fitted well to an equation closely related to the Temkin isotherm. 25 refs., 6 figs., 5 tabs

  17. Nitric acid flowsheet with late wash PHA testing

    International Nuclear Information System (INIS)

    This Task Technical Plan outlines the activities to be conducted in the Integrated DWPF Melter System (IDMS) in ongoing support of the Defense Waste Processing Facility (DWPF) Chemical Process Cell (CPC) utilizing the Nitric Acid Flowsheet in the Sludge Receipt and Adjustment Tank (SRAT) and Precipitate Hydrolysis Aqueous (PHA) produced by the Late Wash Flowsheet. The IDMS facility is to be operated over a series of runs (2 to 4) using the Nitric Acid Flowsheet. The PHA will be produced with the Late Wash Flowsheet in the Precipitate Hydrolysis Experimental Facility (PHEF). All operating conditions shall simulate the expected DWPF operating conditions as closely as possible. The task objectives are to perform at least two IDMS runs with as many operating conditions as possible at nominal DWPF conditions. The major purposes of these runs are twofold: verify that the combined Late Wash and Nitric Acid flowsheets produce glass of acceptable quality without additional changes to process equipment, and determine the reproducibility of data from run to run. These runs at nominal conditions will be compared to previous runs made with PHA produced from the Late Wash flowsheet and with the Nitric Acid flowsheet in the SRAT (Purex 4 and Purex 5)

  18. Containment of nitric acid solutions of Plutonium-238

    Science.gov (United States)

    Reimus, M. A. H.; Silver, G. L.; Pansoy-Hjelvik, L.; Ramsey, K. B.

    1999-01-01

    The corrosion of various metals that could be used to contain nitric acid solutions of Pu-238 has been studied. Tantalum and tantalum/2.5% tungsten resisted the test solvent better than 304L stainless steel and several INCONEL alloys. The solvent used to imitate nitric acid solutions of Pu-238 contained 70% nitric acid, hydrofluoric acid, and ammonium hexanitratocerate.

  19. Plutonium removal from nitric acid waste streams

    International Nuclear Information System (INIS)

    Separations research at the Rocky Flats Plant (RFP) has found ways to significantly improve plutonium secondary recovery from nitric acid waste streams generated by plutonium purifications operations. Capacity and breakthrough studies show anion exchange with Dowex 1.4 (50-100 mesh) to be superior for secondary recovery of plutonium. Extraction chromatography with TOPO (tri-n-octyl-phosphine oxide) on XAD-4 removes the final traces of plutonium, including hydrolytic polymer

  20. Study of lanthanide leaching from phosphosemihydrate by nitric acid

    International Nuclear Information System (INIS)

    Nitric acid leaching of lanthanides from phosphosemihydrate (PSH) prepared by treating the Khibiny apatite concentrate at nitric acid concentration of 2-8% and S:L ratio 1:3 was studied under laboratory conditions. Results of experiments are compared with the data obtained during sulfuric acid leaching. It is shown that during one-stage process nitric acid leaches lanthanides from PSH more effectively that sulfuric acid. However, in case of multiple use of the same solution for successive leaching of several portion of PSH, accumulation of lanthanides in nitric acid solutions occurs less intensively than in sulfuric acid ones

  1. Containment of nitric acid solutions of Plutonium-238

    International Nuclear Information System (INIS)

    The corrosion of various metals that could be used to contain nitric acid solutions of Pu-238 has been studied. Tantalum and tantalum/2.5% tungsten resisted the test solvent better than 304L stainless steel and several INCONEL alloys. The solvent used to imitate nitric acid solutions of Pu-238 contained 70% nitric acid, hydrofluoric acid, and ammonium hexanitratocerate. copyright 1999 American Institute of Physics

  2. Growth of nitric acid hydrates on thin sulfuric acid films

    Science.gov (United States)

    Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

    1994-05-01

    Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1 - 3 × 10-4 Torr H2O and 1 - 2.5 × 10-6 Torr HNO3) and subjected to cooling and heating cycles. FTIR spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

  3. Growth of nitric acid hydrates on thin sulfuric acid films

    Science.gov (United States)

    Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

    1994-01-01

    Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

  4. Contribution to the study of the oxidation reaction of Np(V) by nitric acid catalyzed par nitrous acid

    International Nuclear Information System (INIS)

    The oxidation reaction kinetics of Np(V) to Np(VI) by nitric acid catalyzed by nitrous acid was studied. In a first part, a detailed bibliographical survey was made of the oxidation-reduction reactions of U, Np, Pu, Am with nitrous and nitric acids (51 references). It is shown that only when both the organic and aqueous phases are mixed up, the extraction of a reaction product (NpVI) induces an equilibrium displacement. TBP was used as solvent. It is shown that the extraction of nitrous acid from the solvent enables the nitrous acid concentration to be kept constant and in the same order of magnitude than that of Np. This enables to show that Np(V) and nitrous acid have no simple orders. The temperature and nitric acid concentration dependence was studied. It is shown that tetravalent nitrogen must play a major part in the Np(V) oxidation

  5. Flotation extraction of actinoids and lanthanoids from nitric acid solutions

    International Nuclear Information System (INIS)

    A study was made on possibility of using method of ion flotation for extraction of actinoids and lanthanoids from liquid radioactive wastes of spent fuel reprocessing. For this purpose ion flotation of thorium, plutonium (4), uranium (6) and gadolinium from aqueous nitric acid solutions (HNO3 concentration - from 0.01 up to 5.0 mol/l) was investigated, using lauryl phosphoric acid (LPA) as surfactant-collector. Growth of the degree of separation of metal ions with increase of LPA, introduced into the system, independently of acidity of solutions was established. Decrease of separation degree of uranium (6) and gadolinium with acidity growth and constancy of this parameter for plutonium (4) and thorium are observed at fixed mole LPA/metal ratio. Principle possibility of 100% flotation extraction of plutonium (4) and thorium independently of acidity of aqueous solutions is shown. Addition of 0.5 mol/l Ca(NO3)2 into the system doesn't produce sufficient effect on flotation extraction of thorium

  6. Nitrous oxides desorption from nitric acid (58–60 wt. %)

    OpenAIRE

    Литвиненко, Олександр Олександрович; Печенко, Тамара Ивановна; Подустов, Михаил Алексеевич; Букатенко, Алексей Иванович

    2015-01-01

    The process of nitrous oxides desorption from nitric acid solutions (in domestic schemes) was considered. It is shown that in the process of desorption (or stripping), the nitrous oxides are not removed from solutions completely, so, the nitric acid does not satisfy the technical requirements in Ukraine.The research objective was to bring the quality of nitric acid to technological standards by removing (stripping) nitrous oxides from its solutions.To achieve the research objective, the balan...

  7. Efficient extraction of Rh(III) from nitric acid medium using a hydrophobic ionic liquid.

    Science.gov (United States)

    Bell, Thomas James; Ikeda, Yasuhisa

    2012-04-21

    Rhodium(III) has been successfully extracted from an aqueous nitric acid solution using a hydrophobic ammonium based ionic liquid and CMPO or TODGA as extractant. This result has significant potential for the recovery of rhodium from spent nuclear fuel and thereby increasing the worldwide supply of this rare metal. PMID:22382888

  8. Actinide removal from nitric acid waste streams

    International Nuclear Information System (INIS)

    Actinide separations research at the Rocky Flats Plant (RFP) has found ways to significantly improve plutonium secondary recovery and americium removal from nitric acid waste streams generated by plutonium purification operations. Capacity and breakthrough studies show anion exchange with Dowex 1x4 (50 to 100 mesh) to be superior for secondary recovery of plutonium. Extraction chromatography with TOPO(tri-n-octyl-phosphine oxide) on XAD-4 removes the final traces of plutonium, including hydrolytic polymer. Partial neutralization and solid supported liquid membrane transfer removes americium for sorption on discardable inorganic ion exchangers, potentially allowing for non-TRU waste disposal

  9. The kinetics of the 15N/14N isotopic exchange between nitric oxide and nitric acid

    International Nuclear Information System (INIS)

    The rate of the 15N isotopic exchange between NO-NHO3 at high nitric acid concentration (2-10M) have been measured. The experimental data were obtained by contacting nitric oxide at atmospheric pressure with nitric acid solution labelled with 15N, in a glass contactor. The measurements were carried out in a glass vessel with magnetic stirrer maintaining always the same stirring rate (17 rot.s-1). The temperature was kept constant at 25 +-0.5 deg C. The reaction vessel was connected to a vacuum line and a purified nitric oxide source. The rate of the isotopic exchange and of the nitric oxide absorption in nitric acid were determined with a gas-burette in the simple apparatus described earlier. (T.G.)

  10. Plutonium (4) and neptunium (4) extraction with tributyl phosphate from solutions containing nitric and formic acids

    International Nuclear Information System (INIS)

    Distribution of Pu(4) and Np(4) between 30% solution of tributyl phosphate in dodecane and aqueous solutions containing nitric and formic (HFm) acids has been studied. It is shown that during coextraction of nitric and formic acids mixed solvates in organic phase are not formed. It is established that Pu(4) and Np(4) are reextracted into aqueous phase, containing formic acid at the expense of both displacing and complexing effect of HFm. Equations describing the dependence of concentrational constants of Pu(4) and Np(4) extraction on the content of HNO3 and HFm in aqueous phase are obtained. The equations can be used for mathematical modelling of Pu(4) and Np(4) distribution in the extractional processes

  11. Composition of nitrosyl ruthenium complexes in nitric acid

    International Nuclear Information System (INIS)

    The composition of nitrosyl ruthenium complexes in nitric acid has been determined. The analysis was carried out by low temperature, gradient elution, reversed-phase partition chromatography. Paper chromatography, using methyl isopropyl ketone and nitric acid-acetone, were also carried out to obtain complementary data. (author)

  12. Method of evaporizing ruthenium-containing nitric acid

    International Nuclear Information System (INIS)

    Purpose: To improve the ruthenium decontamination coefficient in nitric acid recovered in the step of dissolving spent fuels into nitric acid in fuel reprocessing. Method: Ruthenium contained as fission products is formed into nitrosyl complex compounds under the effect of nitrogen oxides present together upon dissolving into nitric acid. The complex compounds of nitrosyl ruthenium are decomposed when heated in concentrated nitric acid and, when oxidized further, form volatile ruthenium tetraoxide and evaporized together with nitric acid vapors to reduce the decontaminating coefficients of a nitric acid distillating device. In this invention, the heating time is shortened and the decomposing amount is decreased in the distillating concentration of nitric acid solutions thereby improving the decontaminating coefficients in the distillator by utilizing the fact that the decomposing rate of the nitrosyl ruthenium complex compounds is not always rapid. It is thus possible to improve the decontaminating coefficients up to a limit value determined by the entrainment of liquid droplets and, in addition, corrosion of austenite type stainless steels due to the competition between nitric acid and ruthenium can be improved. (Horiuchi, T.)

  13. Extraction of uranium (VI) and thorium (IV) ions from nitric acid solutions by N.N.N'.N'-tetrabutylsuccinylamiide

    International Nuclear Information System (INIS)

    Solvent extraction of U(VI) and Th(IV) from nitric acid medium by N.N.N'.N'-tetrabutylsuccinylamide(TBSA) in a diluent composed of 50% trimethyl benzene (TMB) and 50% kerosene(OK) is described. Extraction coefficients of U(VI) and Th(IV) as a function of aqueous nitric acid concentration, extractant concentration and temperature have been studied. From the data, the compositions of extracted species, equilibrium constants and enthalpies of extraction reaction are also been calculated

  14. Studies of molybdenite interaction with nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Potashnikov, Yu.M.; Lutsik, V.I.; Chursanov, Yu.V. (Kalininskij Politekhnicheskij Inst. (USSR))

    1984-01-01

    Products composition and their effect on the reaction rate of molybdenite with nitric acid are specified. It is shown that alongside with NO, NO/sub 2/ is included in the composition of the products of MoS/sub 2/ and HNO/sub 3/ interaction, and it produces catalytic effect on the process considered. Under the conditions studied, MoS/sub 2/ dissolution proceeds in the mixed regime, conditioned by similar values of molybdenite oxidation rate and reaction product diffusion into solution volume (Esub(act.=28.9 kJ/mol, K/sub 298/=6.3x10/sup -7/, cmxs/sup -1/), and for that to catalytic effect of NO/sub 2/ the dependence V approximately ..cap alpha..sup(-g.37) is observed.

  15. Studies of molybdenite interaction with nitric acid

    International Nuclear Information System (INIS)

    Product composition and their effect on the reaction rate of molybdenite with nitric acid are specified. It is shown that alongside with NO NO2 is included in the composition of the products of MoS2 and HNO3 interaction and it produces catalytic effect on the process considered. Under the conditions studied MoS2 dissolution proceeds in the mixed regime, conditioned by similar values of molybdenite oxidation rate and reaction product diffusion into solution volume (Esub(act.=28.9 kJ/mol, K298=6.3x10-7, cmxs-1), at that due to catalytic effect of NO2 the dependence V approximately αsup(-g.37) is observed

  16. Studies on the reaction of nitric acid and sugar

    International Nuclear Information System (INIS)

    The design of vessels and off-gas systems for denitrating acidic radioactive process solutions by reacting nitric acid with sugar requires a fairly accurate determination of the rate of the controlling step. Therefore, the reaction of sugar with concentrated nitric acid was closely examined at temperatures of 100 and 1100C and in the presence of low levels of iron )0 to 0.2 M Fe(III)). Efficiencies of the sugar destruction by nitric acid ranged from 2.56 to 2.93 mol of acid consumed per mole of carbon added. Product off-gases were examined throughout the reaction. Release of CO was fairly constant throughout the reaction, but amounts of CO2 increased as the nitric acid began to attack the terminal carboxylic acids produced from the consumption of sucrose. Voluminous quantities of NO2 were released at the beginning of the reaction, but larger relative concentrations of NO were observed toward the end

  17. Adverse experiences with nitric acid at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Durant, W.S.; Craig, D.K.; Vitacco, M.J.; McCormick, J.A.

    1991-06-01

    Nitric acid is used routinely at the Savannah River Site (SRS) in many processes. However, the site has experienced a number of adverse situations in handling nitric acid. These have ranged from minor injuries to personnel to significant explosions. This document compiles many of these events and includes discussions of process upsets, fires, injuries, and toxic effects of nitric acid and its decomposition products. The purpose of the publication is to apprise those using the acid that it is a potentially dangerous material and can react in many ways as demonstrated by SRS experience. 10 refs.

  18. Aqueous Photochemistry of Glyoxylic Acid.

    Science.gov (United States)

    Eugene, Alexis J; Xia, Sha-Sha; Guzman, Marcelo I

    2016-06-01

    Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosols (SOA) from gas phase precursors is relatively well understood, studying aqueous chemical reactions contributing to the total SOA budget is the current focus of major attention. Field measurements have revealed that mono-, di-, and oxo-carboxylic acids are abundant species present in SOA and atmospheric waters. This work explores the fate of one of these 2-oxocarboxylic acids, glyoxylic acid, which can photogenerate reactive species under solar irradiation. Additionally, the dark thermal aging of photoproducts is studied by UV-visible and fluorescence spectroscopies to reveal that the optical properties are altered by the glyoxal produced. The optical properties display periodicity in the time domain of the UV-visible spectrum of chromophores with absorption enhancement (thermochromism) or loss (photobleaching) during nighttime and daytime cycles, respectively. During irradiation, excited state glyoxylic acid can undergo α-cleavage or participate in hydrogen abstractions. The use of (13)C nuclear magnetic resonance spectroscopy (NMR) analysis shows that glyoxal is an important intermediate produced during direct photolysis. Glyoxal quickly reaches a quasi-steady state as confirmed by UHPLC-MS analysis of its corresponding (E) and (Z) 2,4-dinitrophenylhydrazones. The homolytic cleavage of glyoxylic acid is proposed as a fundamental step for the production of glyoxal. Both carbon oxides, CO2(g) and CO(g) evolving to the gas-phase, are quantified by FTIR spectroscopy. Finally, formic acid, oxalic acid, and tartaric acid photoproducts are identified by ion chromatography (IC) with conductivity and electrospray (ESI) mass spectrometry (MS) detection and (1)H NMR spectroscopy. A reaction mechanism is proposed based on all experimental observations. PMID:27192089

  19. Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility

    Science.gov (United States)

    Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

    1990-01-01

    The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

  20. Leaching of sodium carbonate cakes by nitric acid

    International Nuclear Information System (INIS)

    The interaction has been studied of soda cakes of fluorite-rare-earth concentrate with nitric acid. The effect of a number of factors on extraction of REE into a nitric solution has been considered: the final acidity of the pulp, the duration of leaching, and the ratio between solid and liquid phases. The effect of adding aluminium nitrate into the pulp has also been studied. It has been shown that three-stage counterflow leaching of soda cakes with nitric acid increases REE extraction approximately by 10%

  1. Thermodynamics and kinetics of thermal decomposition of dibutylalkyl and dipentylalkyl phosphonate-nitric acid systems

    International Nuclear Information System (INIS)

    Tributyl phosphate (TBP) is used in the reprocessing industry for the separation of uranium and plutonium from the spent nuclear fuels by PUREX process. A variety of dialkylalky/phosphonates were synthesised and their extraction behaviour on actinides was studied in this laboratory. The superior extraction characteristics of phosphonates make them useful for several metal recovery applications in the nuclear fuel cycle. However, higher solubility of phosphonates in aqueous phase as compared to TBP, introduces higher chances of the formation of thermally active 'red oil' like substances during the evaporation of aqueous streams. Thermal stability of neat and nitric acid solvated homologues of four dibutylalkyl phosphonates namely, dibutylpropyl phosphonate (DBPrP), dibutylbutyl phosphonate (DBBP), dibutylpentyl phosphonate (DBPP), dibutylhexyl phosphonate (DBHeP), and two dipentylalkyl phosphonates viz. dipentylbutyl phosphonate (DPBP), dipentylhexyl phosphonate (DPHeP) were studied. Experiments were conducted using an adiabatic calorimeter in heat-wait-search mode. Various stoichiometry of nitric acid-solvated DBalP and DPalP were prepared by equilibrating the respective organic with 4-15.6 M nitric acid followed by separation. Neat DBalP and DPalP are stable up to the temperature of ∼ 555 K while their acid-solvates decomposed in the temperature range 380-403 K. The results also indicated that the presence of nitric acid accelerated the decomposition of phosphonates. Decomposition of these acid solvated phosphonates is found to be exothermic and follows first order kinetics. The onset temperature, adiabatic temperature rise, pressure rise, decomposition enthalpy and activation energy were found to strongly depend on the nitric acid content of the acid-solvates. The studies also indicate that dibutylalkyl and dipentylalkyl phosphonates are also prone to form 'red oil' like substances under extreme conditions and can lead to run-away reactions

  2. Thermal Stability of Acetohydroxamic Acid/Nitric Acid Solutions

    International Nuclear Information System (INIS)

    The transmutation of transuranic actinides and long-lived fission products in spent commercial nuclear reactor fuel has been proposed as one element of the Advanced Accelerator Applications Program. Preparation of targets for irradiation in an accelerator-driven subcritical reactor would involve dissolution of the fuel and separation of uranium, technetium, and iodine from the transuranic actinides and other fission products. The UREX solvent extraction process is being developed to reject and isolate the transuranic actinides in the acid waste stream by scrubbing with acetohydroxamic acid (AHA). To ensure that a runaway reaction will not occur between nitric acid and AHA, an analogue of hydroxyl amine, thermal stability tests were performed to identify if any processing conditions could lead to a runaway reaction

  3. Tropospheric measurements of nitric acid vapor and particulate nitrate

    International Nuclear Information System (INIS)

    Measurements of tropospheric nitric acid and particulate nitrate concentrations as a function of altitude in various marine and continental areas generally free from urban pollution are presented. Air was sampled at altitudes from 0.2 to 8 km, above and within the boundary layer, from 54 deg S to 70 deg N using impregnated filter technology. Most of the samples taken in the northern mid-latitude continental region are observed to contain greater than 0.1 ppbv nitric acid, while the rest of the samples contained significantly less. Particulate nitrate concentrations range from generally less than 0.2 ppbm above the boundary layer to 1.4 ppbm in the continental, urban-influenced boundary layer. Nitric acid is found to exceed particulate nitrate above the boundary layer, however to be considerably less in the marine boundary layer. Implications of these measurements for one-dimensional models of nitric acid gradients and global nitrogen oxide budgets are discussed

  4. NOx generation method from recovered nitric acid by electrolysis

    International Nuclear Information System (INIS)

    A considerable amount of sodium nitrate solution is generated as low-level liquid waste in a spent-fuel reprocessing plant. If the nitric acid recovered from the low-level liquid waste is decomposed into useful materials, such as NOx gas, the nitric acid can be reused and the volume of low-level liquid waste can be greatly reduced. Studies were conducted on electrolytic reduction as a technology for reducing waste volume and producing NOx gas directly from recovered nitric acid in the reprocessing plant. As a result of fundamental research, it was found that NOx could be produced at high current efficiency if nitric acid of 5 - 6 mol/liter or more is electrolytically reduced with graphite or platinum electrodes. (author)

  5. The Iron-Catalyzed Oxidation of Hydrazine by Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Karraker, D.G.

    2001-07-17

    To assess the importance of iron to hydrazine stability, the study of hydrazine oxidation by nitric acid has been extended to investigate the iron-catalyzed oxidation. This report describes those results.

  6. TBP 20% diluent/H N O3/H2 O liquid-liquid extraction system: equilibrium data normalization of nitric acid, ruthenium and zirconium

    International Nuclear Information System (INIS)

    The extraction behavior of nitric acid, nitrosyl ruthenium nitrate and zirconium hydroxide nitrate in the system tri-n-butyl phosphate (TBP) 20% -diluent was studied. The main purpose was to obtain enough data to elaborate process flowsheets for the treatment of irradiated uranium fuels. During the runs, the equilibrium diagrams of nitric acid, ruthenium and zirconium were settled. From the achieved data, the influence of nitric acid, ruthenium, zirconium and nitrate ions concentration in the aqueous phase was checked. Furthermore, the density and the surface tension of the aqueous and organic phases were determined, gathering the interfacial tension after the contact between the phases. (author)

  7. Nitric acid leaching of polymetallic middlings of concentration

    OpenAIRE

    Rogozhnikov, D. A.; Mamyachenkov, S. V.; Karelov, S. V.; Anisimova, O. S.

    2013-01-01

    Investigations into the nitric acid leaching of polymetallic middlings with the purpose of the maximal recovery of copper and zinc into the solution are performed. Using methods of mathematical planning of the experiment, the optimal process parameters are determined: ratio L: S = 5, the consumption of nitric acid is 80 cm3 per 20 g of the charge, and the process duration is 120 min. © 2013 Allerton Press, Inc.

  8. Removal of Methyl Orange from Aqueous Solution by Nitric Acid-Modified Titanium Ore%硝酸掺杂钛精矿吸附去除甲基橙

    Institute of Scientific and Technical Information of China (English)

    雷雪飞; 薛向欣; 杨合

    2012-01-01

    Nitric acid-modified titanium ore (NATO) sorbents were prepared by high energy ball milling process. The adsorption properties of NATO sorbents were evaluated by the decoloration efficiency of methyl orange (MO) under dark-state absorption. In the adsorption stage, L9(34) orthogonal experiments of different factors, for example, doping ratio, calcination temperature, soaking time and heating rate were performed. Based on the orthogonal experiments, the optimal operating parameters, 2.0wt % nitric acid, 300 ℃ calcination temperature, 3 h soaking time, and 10 ℃/min heating rate, are obtained. In this optimal condition, the decoloration efficiency of MO reaches 96.8 %, which is significantly better than the undoped samples. Thus, it is feasible to treat dye wastewater by these NATO sorbents.%采用高能球磨法制备了一系列硝酸掺杂的钛精矿(nitric acid-modified titanium ore,NATO)吸附材料,采用正交表L9(34)安排实验,以甲基橙(MO)溶液的脱色率作为衡量吸附剂优劣的重要判据.以硝酸掺杂比例、煅烧温度、保温时间、升温速率为因素进行正交试验,基于降低能耗和成本的考虑和综合分析的基础上,得到制备NATO吸附剂的最优工艺条件:硝酸掺杂比例为2.0%,煅烧温度为300℃,保温时间为3 h,升温速率为10℃/min.在较优工艺条件下制备的NATO吸附剂对甲基橙的脱色率达到96.8%,明显优于未掺杂样品,且沉降性能较好,易于分离,是一类有应用前景的吸附材料.

  9. Extraction and Separation of Lanthanum (III) and Neodymium (III) from Nitric acid by Aliquat-336 in Kerosene

    International Nuclear Information System (INIS)

    Aliquat-336 (tricapryl methyl ammonium chloride) in kerosene was used as an extractant for La (Ill) and Nd (Ill) from nitric acid medium. The different parameters affecting the extraction of the investigated metal ions such as hydrogen ion concentration, nitric acid, Aliquat-336 concentration, metal ion, loading capacity as well as temperature were separately investigated. The extraction of both cations was found to increase with increasing Aliquat-336, metal ion, nitrate and nitric acid concentration, while it decreases slightly with hydrogen ion concentration. The stoichiometry of the extracted metal species investigated was found to be M (NO3)-4L+ for both cations. The thermodynamic functions were determined and discussed. The stripping of the extracted metal species by nitric, sulphuric, hydrochloric acids and sodium hydroxide were carried out. The difference in the extraction and stripping conditions was used for the separation of La (III) and Nd (Ill) from aqueous nitrate medium.

  10. Nitric acid adduct formation during crystallization of barium and strontium nitrates and their co-precipitation from nitric acid media

    International Nuclear Information System (INIS)

    The molar solubilities of Ba, Sr and Pb nitrates in nitric acid as a function of total nitrate concentration is presented and described by the mass action law, indicating on formation of the adducts with nitric acid. Precipitates of Ba(NO3)2 and Sr(NO3)2 crystallized from nitric acid were studied by ISP OES and IR spectroscopy. The data obtained confirmed formation of metastable adducts with nitric acid. IR and X-ray diffraction studies of the mixed salt systems indicated conversion of the mixed salts into (Ba,Sr)(NO3)2 solid solution of discrete structure in range of total nitrate ion concentration ∼6 mol/L. (author)

  11. Acetic acid extraction from aqueous solutions using fatty acids

    NARCIS (Netherlands)

    IJmker, H.M.; Gramblicka, M.; Kersten, S.R.A.; Ham, van der A.G.J.; Schuur, B.

    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

  12. Thermal decomposition studies on tri-iso-amyl phosphate in n-dodecane-nitric acid system

    International Nuclear Information System (INIS)

    Tri-iso-amyl Phosphate (TiAP) is a promising alternative solvent to TBP, with near similar extraction behaviour and physical properties but lower aqueous phase solubility and does not form third phase during the extraction of Pu(IV). In addition to the solubilised extractant, inadvertent entrainment of the extractant into the aqueous stream is a concern during the evaporation operation as the extractant comes into contact with higher nitric acid concentrations and metal nitrates. Hence the thermal decomposition behaviour of TiAP-HNO3 systems has been studied using an adiabatic calorimeter in closed air ambience, under heat-wait-search mode (H-W-S)

  13. Thermodynamic study on redox reactions of boiling nitric acid solutions

    International Nuclear Information System (INIS)

    In order to understand corrosion of metals in nitric acid solutions, it is necessary to know the generation mechanism of high equilibrium potential in the solutions, especially under boiling conditions. Existing nitrogen oxides in nitric acid solutions were first analyzed by Raman spectroscopy and then existing amount of nitrogen oxides were examined by thermodynamic calculation using the SOLGASMIX software. The Raman spectroscopic analysis showed that the existing amount of un-dissociated HNO3 increased with increasing nitric acid concentration and solution temperature. The existing amount of NO2 also increased by thermal decomposition. The thermodynamic calculation showed that the important nitrogen oxides in nitric acid solutions are HNO3, NO3-, HNO2, NO2, and NO. The equilibrium potential of nitric acid solution is, however, mainly decided by the HNO3/HNO2 equilibrium. The thermodynamic calculation also suggested that the increased oxidization potential on the heat-transfer surface is attributed to the reduction of nitrous acid concentration by the thermal decomposition of nitrous acid on the surface and the continuous removal of decomposition product from the solutions by boiling babbles. (author)

  14. Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.

    Science.gov (United States)

    Raw, C. J. G.; And Others

    1983-01-01

    Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)

  15. Isothermal heat measurements of TBP-nitric acid solutions

    International Nuclear Information System (INIS)

    Net heats of reaction were measured in an isothermal calorimeter for both single phase (organic) and two phase (organic and aqueous) TBP/HNO3 reacting solutions at temperatures above 100 C. The oxidation rate constant was determined to be 5.4E-4 min-1 at 110 C for an open ''vented'' system as compared to 1.33 E-3 min-1 in the closed system. The heat released per unit material oxidized was also reduced. The oxidation in both phases was found to be first order in nitric acid and pseudo-zero order in butylnitrate and water. The hydrolysis (esterification) rate constant determined by Nichols' (1.33E-3 min-1) fit the experimental data from this work well. Forced evaporation of the volatile components by the product gases from oxidation resulted in a cooling mechanism which more than balanced the heat from the oxidation reaction in the two-phased systems. Rate expressions were derived and rate constants determined for both the single and two phase systems. An approximating mathematical model was developed to fit the experimental data and to extrapolate beyond the experimental conditions. This model shows that one foot of ''reacting'' 14.3M HNO3 aqueous phase solution at 121 C will transport sufficient water to the organic phase to replace evaporative losses, maintaining endothermicity, for organic layers up to 12.2 + 6.0 feet deep. If the pressure in a reacting system is allowed to increase due to insufficient venting the temperature of the organic phase would increase in temperature to reach a new equilibrium. The rate of oxidation would increase not only due to the increase in temperature but also from the increased concentration of dissolved HNO3 reduction products. Another important factor is that the cooling system described in this work becomes less effective as the total pressure increases. These factors probably contributed to the explosion at Tomsk

  16. Extraction behaviour of Am(III) and Eu(III) from nitric acid medium in CMPO-HDEHP impregnated resins

    Energy Technology Data Exchange (ETDEWEB)

    Saipriya, K.; Kumar, T. [Bhabha Atomic Research Centre Facilities (India). Kalpakkam Reproscessing Plants; Kumaresan, R.; Nayak, P.K.; Venkatesan, K.A.; Antony, M.P. [Indira Gandhi Center for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

    2016-05-01

    Chromatographic resin containing extractants such as octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) or bis-(2-ethylhexyl)phosphoric acid (HDEHP) or mixture of extractants (CMPO + HDEHP) in an acrylic polymer matrix was prepared and studied for the extraction of Am(III) and Eu(III) over a range of nitric acid concentration. The effect of various parameters such as concentration of nitric acid in aqueous phase and the concentration of CMPO and HDEHP in the resin phase was studied. The distribution coefficient of Am(III) and Eu(III) in the impregnated resin increased with increased in the concentration of nitric acid for CMPO-impregnated resin, whereas a reverse trend was observed in HDEHP impregnated resin. In case of resin containing both the extractants, synergism was observed at low nitric acid concentration and antagonism at high nitric acid concentration. The mechanism of extraction was probed by slope analysis method at 0.01 and 2 M nitric acid concentrations. Citrate-buffered DTPA was used for the selective separation of Am(III), and a separation factor of 3-4 was obtained at pH 3.

  17. Nitric acid measurements in connection with corrosion studies

    Science.gov (United States)

    Ferm, Martin; De Santis, Franco; Varotsos, Costas

    Atmospheric nitric acid does not only contribute to acidification and eutrophication but causes also deterioration of many materials. Material belonging to our cultural heritage is irreplaceable and its lifetime can depend on the corrosion rate. Nowadays, only very few long-term measurements of nitric acid concentration in Europe and elsewhere have been published so far. Due to the fact that atmospheric corrosion is a long-term effect, the relevant research does not necessarily require monitoring of nitric acid on a daily basis. Moreover, power supply is often not available at sites where it is of interest to study the corrosion rate of objects belonging to our cultural heritage. Besides, such measurements must not disturb the impression of the objects. In this context, the diffusive sampling technique provides average concentrations over long-term periods at a low cost. In addition, the samplers used are noiseless, comparatively small in size, and thus, their ambient exposure can be made inconspicuously and with discretion. The present paper is focussed on an intensive corrosion study, which was performed at 11 rural and 23 urban sites in Europe and one rural site in Canada during 2002/2003. For the above-mentioned reasons, the diffusive sampler's technique was employed for the nitric acid monitoring, where the diffusive samplers were first tested against the denuder technique and bi-monthly measurements of nitric acid were thus obtained. The bi-monthly concentrations varied from 0.05 to 4.3 μg m -3 and the annual averages from 0.16 to 2.0 μg m -3. The observations collected, depicted a summertime maximum and a wintertime minimum in the nitric acid concentrations, except at the northern rural sites, where a maximum in the winter was observed. Furthermore, the observed nitric acid concentrations in Southern Europe were higher than in Northern Europe. In a few places, close to the sites of urban measurements, rural measurements of nitric acid were also performed

  18. Removal of iodine species by concentrated nitric acid, (2)

    International Nuclear Information System (INIS)

    One of the most effective removing processes of iodine species is what is called ''Iodox Process'', which contains oxidation and absorption of iodine species by highly concentrated nitric acid. The result of fundamental test with bubble column in this process had been reported. Present paper describes the fundamental experiment by the use of packed column. This experiment has been carried out to clear the effect of feed gas flow rate, nitric acid flow rate, nitric acid concentration, and methyl iodide concentration on removal efficiency of methyl iodide. The following results were obtained. The decontamination factor of methyl iodide (DF) increases exponentially with nitric acid concentration, which agrees with the result obtained by using the bubble column. The factor is in inverse proportion to feed gas flow rate, and is also almost independent of nitric acid flow rate and methyl iodide concentration. The relation between the decontamination factor and the capacity coefficient has been examined, and then the experimental equations of the capacity coefficient and the decontamination factor on this fundamental experiment have been estimated. (author)

  19. Refractory Oxide Coatings on Titanium for Nitric Acid Applications

    Science.gov (United States)

    Ravi Shankar, A.; Kamachi Mudali, U.

    2014-07-01

    Tantalum and Niobium have good corrosion resistance in nitric acid as well as in molten chloride salt medium encountered in spent fuel nuclear reprocessing plants. Commercially, pure Ti (Cp-Ti) exhibits good corrosion resistance in nitric acid medium; however, in vapor condensates of nitric acid, significant corrosion was observed. In the present study, a thermochemical diffusion method was pursued to coat Ta2O5, Nb2O5, and Ta2O5 + Nb2O5 on Ti to improve the corrosion resistance and enhance the life of critical components in reprocessing plants. The coated samples were characterized by XRD, SEM, EDX, profilometry, micro-scratch test, and ASTM A262 Practice-C test in 65 pct boiling nitric acid. The SEM micrograph of the coated samples showed that uniform dense coating containing Ta2O5 and/or Nb2O5 was formed. XRD patterns indicated the formation of TiO2, Ta2O5/Nb2O5, and mixed oxide/solid solution phase on coated Ti samples. ASTM A262 Practice-C test revealed reproducible outstanding corrosion resistance of Ta2O5-coated sample in comparison to Nb2O5- and Ta2O5 + Nb2O5-coated sample. The hardness of the Ta2O5-coated Cp-Ti sample was found to be twice that of uncoated Cp-Ti. The SEM and XRD results confirmed the presence of protective oxide layer (Ta2O5, rutile TiO2, and mixed phase) on coated sample which improved the corrosion resistance remarkably in boiling liquid phase of nitric acid compared to uncoated Cp-Ti and Ti-5Ta-1.8Nb alloy. Three phase corrosion test conducted on Ta2O5-coated samples in boiling 11.5 M nitric acid showed poor corrosion resistance in vapor and condensate phases of nitric acid due to poor adhesion of the coating. The adhesive strength of the coated samples needs to be optimized in order to improve the corrosion resistance in vapor and condensate phases of nitric acid.

  20. Dissolution of unirradiated UO2-pellets in nitric acid

    International Nuclear Information System (INIS)

    Cinetics of dissolution of UO2-pellets in nitric acid and the gaseous reaction products, N2O, NO, NO2 are determined for different temperatures and acid concentrations. NO2:NO ratio increases with temperature and nitrate concentration. The amount of N2O formed increases with temperature and acid concentration. At 900C and dissolution in 12 m nitric acid 1l weight-% of UO2 are dissolved forming N2O. The oxidation of UO2 takes place on the crystal surface or at the interface UO2/HNO3. U(IV)-ions cannot be detected in the solution. The nitrous acid resulting from reduction of HNO3 or the species which is in equilibrium with nitrous acid e.g. the nitrosyl-ion is responsible for UO2-oxidation. (orig./PW)

  1. Diglycolamic acid modified silica gel for the separation of hazardous trivalent metal ions from aqueous solution.

    Science.gov (United States)

    Suneesh, A S; Syamala, K V; Venkatesan, K A; Antony, M P; Vasudeva Rao, P R

    2015-01-15

    The surface of the silica gel was modified with diglycolamic acid moieties and the product (Si-DGAH) was characterized by elemental analysis, TG-DTA, (1)H and (29)Si NMR and scanning electron microscopy (SEM). The adsorption behavior of hazardous americium (III) and europium (III) in Si-DGAH was studied from aqueous nitric acid medium to examine the feasibility using the modified silica for the separation of Am(III) and Eu(III) from aqueous wastes. In this context, the effect of various parameters such as the duration of equilibration, and concentrations of europium, nitric acid, sodium nitrate and diethylenetriaminepentaacetic acid (DTPA) in aqueous phase, on the distribution coefficient (K(d)) of Am(III) and Eu(III) was investigated. The distribution coefficient of ∼10(3) mL/g (>99.9% extraction) was obtained for both Am(III) and Eu(III) at pH 3, and the K(d) values decreased with increase in the concentration of nitric acid. Rapid kinetics of extraction in the initial stages of equilibration, followed by the establishment of equilibrium occurred within 30 min. The extraction data were fitted into Langmuir adsorption model and the apparent europium extraction capacity was determined. Europium loading capacity of the sorbent was determined at various feed pH by column method. The study indicated the possibility of using diglycolamic acid-modified silica for the separation of Eu(III) and Am(III) from aqueous wastes. PMID:25454425

  2. Reactivity of the uranium (U(IV)/U(VI)) and the plutonium (Pu(III)/Pu(IV)) in nitric aqueous solution under ultrasound

    International Nuclear Information System (INIS)

    To minimize the volumes of solid waste and industrial effluents generated at the end of cycle, particularly in the spent nuclear fuel reprocessing industry, research is currently under way on so-called innovative processes, designed to induce chemical reactions without adding reagent to the media. Among these processes, the use of ultrasound can prove advantageous, and the purpose of this study is to assess accurately the potential for its application. In the present context, this work shows that the transmission of an ultrasonic wave in aqueous nitric acid solution leads to: the accumulation of nitrous acid in solution, until a steady-sate concentration is reached; the removal of nitrogen monoxide and nitrogen dioxide in the gas stream. The initial kinetics of the formation of HNO2 in solution was quantified as a function of the nitric acid concentration and the ultrasound intensity. It was also shown than an excess of nitrous acid in nitric solution decomposes under the effect of ultrasound. It is also possible to accumulate hydrogen peroxide in solution during the ultrasonic irradiation of aqueous nitric acid solutions in the presence of a chemical species N2H5+, NH2SO3H...) which reacts rapidly with HNO2, preventing the reduction of H2O2 by HNO2. The mechanisms of HNO2 formation and decomposition, and the mechanism of H2O2 formation during the ultrasonic irradiation of aqueous nitric acid solutions, are presented. Control of H2O2 or HNO2 in a nitric acid medium under the effect of an ultrasonic wave can be exploited to control redox reactions of uranium and plutonium ions, particularly with respect to the oxidation of U and Pu (U(IV)→ U(IV) or Pu(III) → Pu(IV)) and the reduction of Pu (Pu(IV)→ Pu(III). The redox behavior of uranium and plutonium ions in aqueous nitric solution subject to an ultrasonic flux is interpreted in term of effects induced on the reaction medium, and reveals the potential for using ultrasound to cause chemical reactions in

  3. Extraction of U(VI) and Th(IV) from nitric acid solutions with N,N,N',N'-tetrahexylsuccinylamide

    International Nuclear Information System (INIS)

    A new diamide N,N,N',N'-tetrahexylsuccinylamide (THSA) was synthesized, characterised and used for the extraction of U(V) and Th(IV) from nitric acid solutions in a diluent composed of 50% 1,2,4-trimethylbenzene (TMB) and 50% kerosene (OK). Extraction distribution coefficients of U(VI) and Th(IV) as a function of aqueous nitric acid concentration, extractant concentration and temperature have been studied. The composition of extracted species, equilibrium constants and enthalpies of extraction reactions have also been calculated. The IR spectra of saturated extraction of U(VI) and Th(IV) were recorded. (author)

  4. Extraction of uranium, thorium, scandium and zirconium by trioxides of tetraphenyl alkylene diphosphates from nitric acid solutions

    International Nuclear Information System (INIS)

    Some regularities of interphase distribution of microquantities of U(6), Th(4), Sc(3), Zr(4) between aqueous solutions of nitric acid and dichloroethane solutions of tetraphenyl alkylene diphosphine dioxides are studies. Effect of structure of dioxide molecule on own extraction ability and selectivity is considered. Changes of extraction ability of dioxides of alkylenediphosphines with increase of a number of methylene members in chain combining two phosphoryl groups and effect of substituent in the molecule of ethylene diphosphine dioxides on extraction of elements from nitric acid solutions are investigated. Stoichiometry of solvates extracted is determined

  5. Electrochemical behavior of plutonium in nitric acid media

    International Nuclear Information System (INIS)

    The first step of the spent nuclear fuel reprocessing is a dissolution of actinides and fission products in hot nitric acid at high concentration. Among all these species, the knowledge of redox plutonium equilibria with discerning between their oxidation states is essential to understand and depended on many chemical conditions. Nevertheless, the knowledge of speciation in this media is a challenge especially for a better understanding of corrosion mechanism in the dissolution medium. Thus this paper proposes to determine the electrochemical behaviour of plutonium and especially the Pu(IV)/Pu(III), Pu(VI)/ Pu(V) and Pu(V)/Pu(IV) redox couple in nitric acid media and acquire thermodynamic and kinetic constants at higher temperatures than 25 deg C and higher nitric concentration than 1 mol L-1. (author)

  6. Study of ruthenium complexation by 22' bipyridine in nitric aqueous solutions

    International Nuclear Information System (INIS)

    Substitution of the NO3-, NO+ ions of RuNO(NO3)x.yH2Osup((3-x)+) complexes by 22'bipyridine (bipy) in nitric aqueous solution was studied by spectrophotometry. In the absence of reducing agent we observe the species RuNO(bipy)(NO3)sub(z)sup((3-z)+) and RuNO(bipy)2NO32+. Most reducing agents give rise to the RuNO(bipy)2NO32+ + e → RuNO(bipy)2NO3+ reaction. The oxydation potential of the reversible couple RuNO(bipy)2NO32+/RuNO(bipy)2NO3+ was measured by cyclic voltamperometry at the platinum electrode. Its value is + 1.02 V/NHE. Substitution of NO+ ions by a (bipy) molecule is only possible in the presence of reducing agents of apparent formal potential below + 0.5 V/NHE, and anti-nitrite agents are also needed; these two functions can be fulfilled by hydrazine and ascorbic acid. The presence of HSO3 NH2 was necessary to obtain the substitution of NO+ and NO3- by bipy during electrochemical reductions. The intermediate complexes RuNO(bipy)2NO32+ and RuNO(bipy)2NO3+ probably include two bipy molecules in the trans position whereas RuNO(bipy)22+ complexes, where the sixth coordination position is occupied by π donors stronger than NO3-, have two bipy molecules in the cis position

  7. Removal of plutonium from nitric acid-oxalic acid solutions using anion exchange method

    International Nuclear Information System (INIS)

    An anion exchange method using Amberlyst A-26 (MP) resin was developed for removal of Pu from nitric acid-oxalic acid solutions without destroying oxalate. The method consists of sorption of Pu(IV) on Amberlyst A-26, a macroporous anion exchange resin, from nitric acid-oxalic acid medium in the presence of Al(NO3)3. Pu(IV) breakthrough capacity of Amberlyst A-26 using synthetic feed solution was determined. (author)

  8. Aluminium dissolution for spray pulverization with nitric acid

    International Nuclear Information System (INIS)

    A comparative study of the nitric acid dissolution of aluminium, by immersion and spray pulverization has been carried out in laboratory scale. As a result, the optimum operation conditions to control reaction in the plant are fixed. Operation costs are also evaluated. (author)

  9. The nitric acid burn trauma of the skin.

    Science.gov (United States)

    Kolios, L; Striepling, E; Kolios, G; Rudolf, K-D; Dresing, K; Dörges, J; Stürmer, K M; Stürmer, E K

    2010-04-01

    Nitric acid burn traumata often occur in the chemical industry. A few publications addressing this topic can be found in the medical database, and there are no reports about these traumata in children. A total of 24 patients, average 16.6 years of age, suffering from nitric acid traumata were treated. Wound with I degrees burns received open therapy with panthenol-containing creams. Wound of II degrees and higher were initially treated by irrigation with sterile isotonic saline solution and then by covering with silver-sulphadiazine dressing. Treatment was changed on the second day to fluid-absorbent foam bandages for superficial wounds (up to IIa degrees depth) and occlusive, antiseptic moist bandages in combination with enzymatic substances for IIb degrees -III degrees burns. After the delayed demarcation, necrectomy and mesh-graft transplantation were performed. All wounds healed adequately. Chemical burn traumata with nitric acid lead to specific yellow- to brown-stained wounds with slower accumulation of eschar and slower demarcation compared with thermal burns. Remaining wound eschar induced no systemic inflammation reaction. After demarcation, skin transplantation can be performed on the wounds, as is commonly done. The distinguishing feature of nitric-acid-induced chemical burns is the difficulty in differentiation and classification of burn depth. An immediate lavage should be followed by silver sulphadiazine treatment. Thereafter, fluid-absorbent foam bandages or occlusive, antiseptic moist bandages should be used according to the burn depth. Slow demarcation caused a delay in performing surgical treatments. PMID:19875347

  10. Oxidation of coal-based raw materials by nitric acid

    Czech Academy of Sciences Publication Activity Database

    Novák, J.; Novák, František; Madronová, L.; Machovič, V.; Kozler, J.

    New York : Nova Science Publisher, 2011 - (Madronová, L.), s. 105-123 ISBN 978-1-61668-965-0. - ( Chemistry Research and Applications ) Institutional research plan: CEZ:AV0Z60660521 Keywords : oxidation * coal-based raw materials * nitric acid Subject RIV: CB - Analytical Chemistry , Separation

  11. Corrosion fatigue behavior of zirconium in boiling nitric acid

    International Nuclear Information System (INIS)

    The corrosion fatigue behavior of zirconium in boiling nitric acid has been studied to evaluate the reliability of zirconium used in nuclear fuel reprocessing equipment. An apparatus designed for corrosion fatigue tests in boiling nitric acid was used. The crack growth rate of zirconium was measured as a function of the stress intensity factor using TDCB type specimens. After the tests, the fracture morphology was examined with a scanning electron microscope. The crack growth rate was influenced with the texture of specimens and the test environments. In air at room temperature, the crack growth rate at the longitudinal direction of specimens was faster than that of the transverse direction. Moreover, the crack growth rate in boiling nitric acid was more faster than that in air at room temperature. According to the fractographic examination, X-ray analysis, and so on, the observed results were interpreted with based on the crystal anisotropy on mechanical properties and the susceptibility to stress corrosion cracking in boiling nitric acid of zirconium. (author)

  12. The stability of N, N-dimethylhydroxylamine in nitric acid

    International Nuclear Information System (INIS)

    The purity of N, N-dimethylhydroxylamine(DMHAN) has been analyzed and the results indicate that the DMHAN synthesized by ourself contains few impurities and meets the needs of the experiment. A titration method for determination of the concentration of DMHAN has been established based on the potassium dichromate titration after the ferric oxidation. The ratio of DMHAN to ferric in the oxidation of DMHAN is found to be 1:4. Methanol, formaldehyde, and formic acid, which are possible oxidized products of DMHAN, do not influence the result of analysis. Using this titration method, the stability of DMHAN in nitric acid has been studied and we found that the decomposition of DMHAN in nitric acid depends on temperature and the concentration of nitric acid: the decomposition of DMHAN increases with the increasing of acidity and temperature although the concentration of DMHAN has little change under certain acidity and temperature, and DMHAN is decomposed quickly when the temperature is higher than 35 degree C and the acidity is higher than 3.0 mol/L. (authors)

  13. Uranium sorption from nitric acid solutions by cationites and polyampholytes

    International Nuclear Information System (INIS)

    Sorption of uranium ions with KU-2 x 8 sulfonic cation exchanger, KFP-12 phosphoric acid cation exchanger and aminophosphoric acid ampholytes was examined in nitric acid solutions containing different amounts of HNO3. Formation of polymeric complexes was confirmed by IR spectra. The ion-coordination mechanism of U sorption with KFP-12 cation exchanger was clearly manifested; sorption of U as a single-charged nitrate complex ion is also possible. The isotherms of sorption of the U ions with KFP-12 cation exchanger have a convex shape with a sharply ascending portion at low U concentrations, which is favorable for U recovery from raffinate solutions. Nitrogen-phosphorus-containing polyampholytes also possess a high sorption power with respect to the U ions in nitric acid solutions. The highest exchange capacity is exhibited by polyacrylate base ANKF-80 and ANKF-86 polyampholytes

  14. 77 FR 48433 - New Source Performance Standards Review for Nitric Acid Plants

    Science.gov (United States)

    2012-08-14

    ... Federal Register on December 23, 1971 (36 FR 24881). The first review of the Nitric Acid Plants NSPS was... requirements for new nitric acid production units? IV. Summary of Significant Changes Since Proposal A. How is..., Energy, and Economic Impacts of These Standards A. What are the impacts for Nitric Acid Production...

  15. 76 FR 63878 - New Source Performance Standards Review for Nitric Acid Plants

    Science.gov (United States)

    2011-10-14

    ... of the Nitric Acid Plants NSPS was completed on June 19, 1979 (44 FR 35265). An additional review was... ) emission limit, which applies to each nitric acid production unit commencing construction, modification, or... questions about these proposed standards for nitric acid production units, contact Mr. Chuck French,...

  16. Dissolutions of oxide dispersion strengthened ferritic steels in various nitric acid solutions. Martensitic 9Cr-ODS steels

    International Nuclear Information System (INIS)

    Corrosion resistance of fuel pin cladding tube materials is one of the most important properties to design advanced aqueous reprocessing process. The martensitic oxide dispersion strengthened ferritic steel, named as '9Cr-ODS' steel, is the primary candidate material for high burnup fuel pin cladding tube in fast reactor cycle system. Because 9Cr-ODS steel contains lower chromium than stainless steels, oxidizing species such as high nitric acid concentrations and metallic ions need to reduce its corrosion rate. In nitric acid medium in contact with 9Cr-ODS steel, both nitric acid and metallic ions concentrations gradually change and stabilize protective passive layer effectively in rotary drum type continuous dissolvers. (author)

  17. IN-VITRO EVALUATION OF NITRIC OXIDE SCAVENGING ACTIVITY OF METHANOLIC AND AQUEOUS EXTRACT OF SYZYGIUM CUMINI LINN. BARK (MYRTACEAE

    Directory of Open Access Journals (Sweden)

    Kuncha Jayachandra et al.

    2012-02-01

    Full Text Available Plants have provided mankind with herbal remedies for many diseases for many centuries and eventody. In India, herbal medicines have been the basis of treatment and cure for various diseases in traditional methods practiced such as Ayurveda, Unani and Sidha. Syzygium cumini Linn. (Myrtaceae commonly known as jambul tree (English, having promising theraputic values with its various phytoconstituents. Preliminary Phytochemical investigation was carried out on the methanolic extract of Syzygium cumini Linn. Bark. It indices presence of Carbohydrates, Amino acids, Tannins, Saponins, phytosterols, Terpenoids, phenols and flavonoids. We are also quantitatively estimated total phenolic content, tannins and favaniods by using spectrophotometer. The total phenolic content was 580.23 ± 3.03 mg/g, tannin content was 534 ± 4.03 mg/ g while the flavonoid content was 315.42 ± 4.52 mg/g. The methanolic and aqueous extracts of bark were screened for antioxidant activity using Nitric oxide scavenging activity method, which showed significant persentage of inhibition in dose dependent manner. As antioxidant therapy is found to be useful in complicated disease status related with free radical activity. This is the first research report regarding Invitro evaluation of Nitric oxide scavenging activity of Methanolic and aqueous extracts of Syzygium cumini bark. The present study might be extended for the formulation and evaluation of different antioxidant herbal dosage forms.

  18. Buffering effects on electrograining of aluminium in nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Koroleva, E.V. [Corrosion and Protection Centre, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: e.koroleva@umist.ac.uk; Thompson, G.E. [Corrosion and Protection Centre, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom); Skeldon, P. [Corrosion and Protection Centre, UMIST, P.O. Box 88, Manchester M60 1QD (United Kingdom); Hollrigl, G. [Alcan Technology and Management Ltd., Bad. Bahnhofstrasse 16, CH-8212 Neuhausen (Switzerland); Lockwood, S. [Bridgnorth Aluminium Limited, Stourbridge Road, Bridgnorth WV15 6AU (United Kingdom); Smith, G. [Bridgnorth Aluminium Limited, Stourbridge Road, Bridgnorth WV15 6AU (United Kingdom)

    2005-09-01

    Electrograining of a binary Al-Si alloy has been undertaken in nitric acid based electrolytes, with the resultant surfaces examined by scanning and transmission electron microscopies. Depending on electrograining conditions, the pit appearance varies from hemispherical to large lateral pits, with the latter favoured in relatively acidic electrolytes. The conditions prevailing in the pit have been explored through use of aluminium ion additions to the nitric acid electrolyte as well as additions of species which influence the precipitation and dissolution of aluminium hydroxide. These confirm that control of the pit solution pH, through hydroxide generation, as a result of the selected electrograining conditions and consequent anodic and cathodic polarisation, enables tailoring of the resultant electrograined surface appearance.

  19. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, R.

    2012-02-22

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. For 6 M HNO{sub 3}, 10.5 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2 g/L and 0.25 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}.

  20. 40 CFR 418.50 - Applicability; description of the nitric acid subcategory.

    Science.gov (United States)

    2010-07-01

    ... are applicable to discharges resulting from production of nitric acid in concentrations up to 68... nitric acid subcategory. 418.50 Section 418.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Nitric...

  1. Separation of Rare Earth Concentrate from Nitric Acid and Sulphuric Acid in Fertilizers production Processing

    International Nuclear Information System (INIS)

    Different processes were proposed and applied for the treatment of a phosphate rocks for the recovery of the rare earth concentrate (REC). The processes assure the production of phosphatic fertilizers without polluting the environment with traces radioactive materials. Two individual systems were utilized for the recovery of REC using nitric acid and sulphuric acid as leaching agents. In nitric acid about 90% of the REC pass into the phosphoric acid solution and was precipitated by neutralization with ammonia up to ph 1.8±0.1. In the sulphuric acid the REC extraction is about 60%. Sulphuric acid is preferred economically where the use of nitric acid needs purification processes from nitrate anions. A mixed method based on each one was investigated to get a more economical recovery

  2. Omega-3 fatty acids improve psychomotor performance via mechanism not related to nitric acid production

    OpenAIRE

    Al-Nimer, Marwan S M; Ali I Al-Gareeb; Hayder M. Al-kuraishy

    2012-01-01

    Omega-3 fatty acids (ω-3FAs) are essential polyunsaturated fats that protect the brain from cognitive impairment. It increases the activity of endothelial nitric oxide synthetase (eNOS) and thereby increases the nitric acid (NO) production. This study aimed to explore the effect of ω-3FAs on psychomotor performance and to relate this effect to the reactive nitrogen species. This study was conducted in Department of Pharmacology, College of Medicine, Al-Mustansiriya University in Baghdad, Iraq...

  3. Extraction behavior of cerium by tetraoctyldiglycolamide from nitric acid solutions

    International Nuclear Information System (INIS)

    The diamide N,N,N',N'-tetraoctyldiglycolamide (TODGA) was synthesized and characterized. The prepared TODGA was applied for extraction of Ce(III) from nitric acid solutions. The equilibrium studies included the dependencies of cerium distribution ratio on nitric acid, TODGA, nitrate ion, hydrogen ion and cerous ion concentrations. Analysis of the results indicates that the main extracted species is Ce(TODGA)2(NO3)3HNO3. The capacity of Ce loading is approximately 45 mmol/L for 0.1 M solution of TODGA in n-hexane. Finally, the thermodynamic parameters were calculated: K (25 deg C) = 3.8 x 103, ΔH = -36.7 ± 1.0 kJ/mol, ΔS = -54.6 ± 3.0 J/K mol, and ΔG = -20.4 ± 0.1 kJ/mol. (author)

  4. Removal of iodine species by concentrated nitric acid, (5)

    International Nuclear Information System (INIS)

    In the reprocessing of FBR spent fuel, it is important to retain radioiodine inside the process. The trapping of the iodine in hyperazeotropic nitric acid is promising to retain radioiodine (Iodox process). Considerable amount of nitrogen oxides is contained in the off-gas. The effects of NO2 on the trapping of methyl iodide are described. (1) The nitrite concentration in nitric acid is easily reduced to less than 10-3 mol/l by aeration, and after this operation, higher decontamination factor DF is expected. (2) NO2 in gas phase reduces the DF significantly even at the concentration as low as 0.5 vol. %. (3) Capacity coefficient is independent of the flow rate of liquid, it increases as the flow rate of gas increases in 19.8 N HNO3, but it does not increase at 18.5 N. (J.P.N.)

  5. UV Photodissociation Dynamics of Nitric Acid: The Hydroxyl Elimination Channel

    Institute of Scientific and Technical Information of China (English)

    Fengyan Wang; Zhichao Chen; Yongwei Zhang; Quan Shuai; Bo Jiang; Dongxu Dai; Xiuyan Wang; Xueming Yang

    2009-01-01

    Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected by (2+1) resonance enhanced multiphoton ionization via the D2∑- electronic state. The total kinetic energy spectra of the OH+NO2 channel from the photolysis of HONO2 show that both NO2(X2A1) and NO2 (A2B2) channels are present,suggesting that both 11A" and 21A" excited electronic states of HONO2 are involved in the excitation. The parallel angular distributions suggest that the dissociation of the nitric acid is a fast process in comparison with the rotational period of the HNO3 molecule. The anisotropy parameter β for the hydroxyl elimination channel is found to be dependent on the OH product rotational state as well as the photolysis energy.

  6. Energy integration of nitric acid production using pinch methodology

    OpenAIRE

    Ivaniš Gorica R.; Lazarević Marija; Radović Ivona R.; Kijevčanin Mirjana Lj.

    2015-01-01

    Pinch methodology was applied to the heat exchangers network (HEN) synthesis of nitric acid production. The integration is analyzed in two ways, and the results are presented as two different solutions: (i) the first solution is based on the original heat transfer equipment arrangement, (ii) in order to eliminate the shortages of the first solution the second HEN was obtained using process simulation with optimized process parameters. Optimized HEN, with ne...

  7. Electrodeposition of ruthenium, rhodium and palladium from nitric acid and ionic liquid media: Recovery and surface morphology of the deposits

    International Nuclear Information System (INIS)

    Research highlights: → Platinum group metals are man-made noble metals. → Electrochemical recovery of fission platinoids. → Recovery from nitric acid medium. → Recovery from ionic liquid medium. → Platinoids with exotic surface morphologies. - Abstract: Electrodeposition is a promising technique for the recovery of platinum group metals with unique surface morphologies. The electrodeposition of palladium, ruthenium and rhodium from aqueous nitric acid, and non-aqueous 1-butyl-3-methylimidazolium chloride ionic liquid medium was studied at stainless steel electrode. The surface morphology and elemental composition of the resultant deposit were probed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analysis. Deposits with diverse surface morphologies and metal compositions were obtained by varying the composition of the electrolytic medium and applied potential. The results demonstrate the possibility of tailoring the morphologies of PGMs by controlling the composition and potential needed for electrodeposition.

  8. NIR Spectroscopic Properties of Aqueous Acids Solutions

    Directory of Open Access Journals (Sweden)

    Mohd Zubir MatJafri

    2012-06-01

    Full Text Available 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.

  9. Stress corrosion cracking of zirconium in nitric acid

    International Nuclear Information System (INIS)

    The susceptibility of zirconium and its common alloys to stress corrosion cracking (SCC) in nitric acid was investigated by slow strain-rate and constant deflection techniques. Cracking occurred at 250C over a wide range of acid concentrations and electrochemical potentials. The crack velocity increased slightly with increasing temperature. The failure mode was transgranular and the morphology was similar to SCC failures of zirconium alloys in other environments. The fracture was very orientation-dependent suggesting that it occurs on a single crystallographic plane in the material. The results of the study are not consistent with a hydrogen mechanism for cracking

  10. The influence of nitric acid on the cloud processing of aerosol particles

    OpenAIRE

    Romakkaniemi, S.; Kokkola, H.; Lehtinen, K.E.J.; Laaksonen, A

    2005-01-01

    In this paper we present simulations of the effect of nitric acid (HNO3) on cloud processing of aerosol particles. Sulfuric acid (H2SO4) production and incloud coagulation are both affected by condensed nitric acid as nitric acid increases the number of cloud droplets, which will lead to smaller mean size and higher total surface area of droplets. As a result of increased cloud droplet number concentration (CDNC), the incloud coagulation rate is enhanced by a factor of 1...

  11. Cyclopiazonic acid degradation by aqueous ozone

    OpenAIRE

    Silva, Otniel Freitas; Venâncio, Armando

    2011-01-01

    Ozone is a chemical agent with great potential to reduce mycotoxins, it was effective against to reduce some mycotoxins. In view of this it was aimed of this work study the Cyclopiazonic acid (CPA) degradation by aqueous ozone. The degradation of exogenously CPA introduced in mobile phase was confirmed by High performance liquid Chromatography (HPLC). In parallel it was tested the effect of sodium formate (SF), to evaluate the influence of this chemical to neutralize ...

  12. Alternative to Nitric Acid for Passivation of Stainless Steel Alloys

    Science.gov (United States)

    Lewis, Pattie L.; Kolody, Mark; Curran, Jerry

    2013-01-01

    Corrosion is an extensive problem that affects the Department of Defense (DoD) and National Aeronautics and Space Administration (NASA). The deleterious effects of corrosion result in steep costs, asset downtime affecting mission readiness, and safety risks to personnel. Consequently, it is vital to reduce corrosion costs and risks in a sustainable manner. The DoD and NASA have numerous structures and equipment that are fabricated from stainless steel. The standard practice for protection of stainless steel is a process called passivation. Typical passivation procedures call for the use of nitric acid; however, there are a number of environmental, worker safety, and operational issues associated with its use. Citric acid offers a variety of benefits including increased safety for personnel, reduced environmental impact, and reduced operational cost. DoD and NASA agreed to collaborate to validate citric acid as an acceptable passivating agent for stainless steel. This paper details our investigation of prior work developing the citric acid passivation process, development of the test plan, optimization of the process for specific stainless steel alloys, ongoing and planned testing to elucidate the process' resistance to corrosion in comparison to nitric acid, and preliminary results.

  13. Metals for the containment of nitric acid solutions of plutonium-238

    International Nuclear Information System (INIS)

    Results of a study of the corrosion of various transition-metal alloys, tantalum, and tantalum/2.5% tungsten are reported. The solvent contained nitric acid, hydrofluoric acid, and ammonium hexanitratocerate. It was designed to imitate the corrosiveness of the nitric acid, hydrofluoric acid mixture used to dissolve 238-plutonium dioxide. (author)

  14. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  15. Nitric-phosphoric acid oxidation of organic waste materials

    International Nuclear Information System (INIS)

    A wet chemical oxidation technology has been developed to address issues facing defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate a heterogenous mixture of radioactive-contaminated solid waste, the technology can also remediate other hazardous waste forms. The process, unique to Savannah River, offers a valuable alternative to incineration and other high-temperature or high-pressure oxidation processes. The process uses nitric acid in phosphoric acid; phosphoric acid allows nitric acid to be retained in solution well above its normal boiling point. The reaction converts organics to carbon dioxide and water, and generates NOx vapors which can be recycled using air and water. Oxidation is complete in one to three hours. In previous studies, many organic compounds were completely oxidized, within experimental error, at atmospheric pressure below 180 degrees C; more stable compounds were decomposed at 200 degrees C and 170 kPa. Recent studies have evaluated processing parameters and potential throughputs for three primary compounds: EDTA, polyethylene, and cellulose. The study of polyvinylchloride oxidation is incomplete at this time

  16. Experimental study on thermal hazard of tributyl phosphate-nitric acid mixtures using micro calorimeter technique.

    Science.gov (United States)

    Sun, Qi; Jiang, Lin; Gong, Liang; Sun, Jin-Hua

    2016-08-15

    During PUREX spent nuclear fuel reprocessing, mixture of tributyl phosphate (TBP) and hydrocarbon solvent are employed as organic solvent to extract uranium in consideration of radiation contaminated safety and resource recycling, meanwhile nitric acid is utilized to dissolve the spent fuel into small pieces. However, once TBP contacts with nitric acid or nitrates above 130°C, a heavy "red oil" layer would occur accompanied by thermal runaway reactions, even caused several nuclear safety accident. Considering nitric acid volatility and weak exothermic detection, C80micro calorimeter technique was used in this study to investigate thermal decomposition of TBP mixed with nitric acid. Results show that the concentration of nitric acid greatly influences thermal hazard of the system by direct reactions. Even with a low heating rate, if the concentration of nitric acid increases due to evaporation of water or improper operations, thermal runaway in the closed system could start at a low temperature. PMID:27136728

  17. Monohydroxamic acids and bridging dihydroxamic acids as chelators to ruthenium(III) and as nitric oxide donors: syntheses, speciation studies and nitric oxide releasing investigations.

    Science.gov (United States)

    Griffith, Darren; Krot, Krystyna; Comiskey, Jedd; Nolan, Kevin B; Marmion, Celine J

    2008-01-01

    The synthesis and spectroscopic characterisation of novel mononuclear Ru(III)(edta)(hydroxamato) complexes of general formula [Ru(H2edta)(monoha)] (where monoha = 3- or 4-NH2, 2-, 3- or 4-C1 and 3-Me-phenylhydroxamato), as well as the first example of a Ru(III)-N-aryl aromatic hydroxamate, [Ru(H2edta)(N-Me-bha)].H2O (N-Me-bha = N-methylbenzohydroxamato) are reported. Three dinuclear Ru(III) complexes with bridging dihydroxamato ligands of general formula [{Ru(H2edta)}2(mu-diha)] where diha = 2,6-pyridinedihydroxamato and 1,3- or 1,4-benzodihydroxamato, the first of their kind with Ru(III), are also described. The speciation of all of these systems (with the exception of the Ru-1,4-benzodihydroxamic acid and Ru-N-methylbenzohydroxamic systems) in aqueous solution was investigated. We previously proposed that nitrosyl abstraction from hydroxamic acids by Ru(III) involves initial formation of Ru(III)-hydroxamates. Yet, until now, no data on the rate of nitric oxide (NO) release from hydroxamic acids has been published. We now describe a UV-VIS spectroscopic study, where we monitored the decrease in the ligand-to-metal charge-transfer band of a series of Ru(III)-monohydroxamates with time, with a view to gaining an insight into the NO-releasing properties of hydroxamic acids. PMID:18399240

  18. Optimization of conditions to produce nitrous gases by electrochemical reduction of nitric acid

    International Nuclear Information System (INIS)

    Gaseous nitrogen oxides (NO and NO2) involved as oxidizing agents in nuclear fuel reprocessing can be an produced by electrochemical reduction of nitric acid. This could be an interesting alternative to the usual process because no wastes are generated. Voltammetric studies on a platinum electrode show that two reduction potential regions are observed in concentrated nitric acid solutions, between 0.05 VSHE and 0.3 VSHE and O.5 VSHE and 1 VSHE. The highest potential region reduction mechanism was studies by: classical micro-electrolysis methods; macro-electrolysis methods; infra-red spectroscopy couplet to electrochemistry. It was determined that the origin of nitric acid reduction is the electrochemical reduction of nitrous acid in nitric oxide which chemically reduces nitric acid. This reaction produces nitrous acid back which indicate an auto-catalytic behaviour of nitric acid reduction mechanism. Nitrogen dioxide evolution during nitric acid reduction can also be explained by an other chemical reaction. In the potential value of platinum electrode is above 0.8 VSHE, products of the indirect nitric acid reduction are nitrous acid, nitrogen oxide and nitrogen dioxide. Below this value nitric oxide can be reduced in nitrous oxide. Thus the potential value is the most important parameter for the nitrogen oxides production selectivity. However, owing to the auto-catalytic character of the reduction mechanism, potential value can be controlled during intentiostatic industrial electrolysis. (author)

  19. Simultaneous Measurement of Nitrous Acid,Nitric Acid, and Nitrogen Dioxide by Means \

    Czech Academy of Sciences Publication Activity Database

    Vichi, F.; Mašková, Ludmila; Frattoni, M.; Imperiali, A.; Smolík, Jiří

    2016-01-01

    Roč. 4, FEB 22 (2016), s. 4. ISSN 2050-7445. [International Conference on Indoor Air Quality in Heritage and Historic Environments /11./. Prague, 13.04.2014-16.04.2014] Institutional support: RVO:67985858 Keywords : diffusive sampling * nitrous acid * nitric acid Subject RIV: CF - Physical ; Theoretical Chemistry

  20. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, R. A.

    2012-03-12

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 °C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. At 25 °C, for 6 M HNO{sub 3}, 11 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2.5 g/L and 0.8 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}. The solubility of Gd in 4 M HNO{sub 3} with 0.15 M oxalate at 10 °C is about 1.5 g/L. For 6 M HNO{sub 3} with 0.15 M oxalate, the solubility of Gd at 10

  1. Study of iodine recovery with platinum-active carbon from nitric acid solution

    International Nuclear Information System (INIS)

    Platinum-Active Carbon (Pt-C) was synthesized and its adsorption and desorption properties in low acidity nitric solution were discussed. It showed that Pt-C can absorb I- and IO3- with high exchange capacity in nitric acid solution, and the recovery rate of I-and IO3- is more than 90%, thus Pt-C can be used for iodine recovery in low acidity nitric solution. (authors)

  2. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

    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 HClO4 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 UO2F2. Studies on the effect of added LiNO3 or Na2WO4·2H2O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF6 content of WF6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF6

  3. Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

    Energy Technology Data Exchange (ETDEWEB)

    R.L. Ames

    2004-09-01

    Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate

  4. Recovery of plutonium from nitric-acid waste streams

    International Nuclear Information System (INIS)

    Nitric acid (7M) waste streams at Rocky Flats contain 0.01 to 0.001 g/1 plutonium and new processes are under development to reduce the plutonium levels to 10-5 g/1. Anion exchange and solvent extraction methods are under evaluation. Several macroreticular and microreticular anion exchange resins were evaluated and Rohm and Hass (IRA-938) gave significant improvement in plutonium capacity and elution over several other resins tested. The solvent extraction process uses dihexyl-N, N-diethylcarbamylmethylene phosphonate extractant. The results of recent tests using a combined anion exchange extraction chromatography process will be described for recovering both plutonium and americum

  5. Energy integration of nitric acid production using pinch methodology

    Directory of Open Access Journals (Sweden)

    Ivaniš Gorica R.

    2015-01-01

    Full Text Available Pinch methodology was applied to the heat exchangers network (HEN synthesis of nitric acid production. The integration is analyzed in two ways, and the results are presented as two different solutions: (i the first solution is based on the original heat transfer equipment arrangement, (ii in order to eliminate the shortages of the first solution the second HEN was obtained using process simulation with optimized process parameters. Optimized HEN, with new arrangement of heat exchangers, gave good results in energy and process optimization. [Projekat Ministarstva nauke Republike Srbije, br. P172063

  6. Investigation of products of molybdenite oxidation by nitric acid

    International Nuclear Information System (INIS)

    Physicochemical study of products of oxidation by nitric acid of molybdenum concentrate containing 98% MoS2 is carried out. It is shown that appearing molybdenum oxide forms block oxidizer access to the surface of sulfide phase and hinder its complete oxidation. When complexing reagents (H2SO4, H3PO4, HCl) are introduced in the solution the bulk of oxidized molybdenum transfers into solution in the form of a stable complex, at that. The effect of internal diffusion decreases and a considerable increase of MoS2 oxidation rate and completeness is achieved

  7. Distribution behaviour of Pa and U in the presence of Th from nitric acid medium using di-2-ethyl hexyl isobutyramide (D2EHIBA)

    International Nuclear Information System (INIS)

    Distribution behaviour of Pa and U has been investigated in the presence of macro amounts of Th from aqueous nitric acid employing 1 M solution of di-2-ethyl hexyl isobutyramide (D2EHIBA) in n-dodecane at 25 deg C. A significant decrease in Pa extraction as compared to U extraction with increase in aqueous Th concentration suggests better separation of U over Pa from the irradiated Th matrix. (author)

  8. Optimization of the nitrous vapors experimental conditions production by nitric acid electrochemical reduction

    International Nuclear Information System (INIS)

    Gaseous nitrogen oxides (NO and NO2) involved as oxidizing agents in nuclear fuel reprocessing can be produced by electrochemical reduction of nitric acid. This is an interesting alternative to the existing process because no wastes are generated. voltammetric studies on a platinum electrode show that two reduction potential regions are observed in concentrated nitric acid solutions, between 0,05 VSHE and between 0,5 VSHE and 1 VSHE. The highest potential region reduction mechanism was studied by: classical micro-electrolysis methods, macro-electrolysis methods, infrared spectroscopy coupled to electrochemistry. It was determined that the origin of nitric acid reduction is the electrochemical reduction of nitrous acid in nitric oxide which chemically reduces nitric acid. This reaction produces nitrous acid back which indicate an auto-catalytic behaviour of nitric acid reduction mechanism. Nitrogen dioxide evolution during nitric reduction can also explained by an other chemical reaction. If the potential value of platinum electrode is above 0,8 VSHE, products of the indirect nitric acid reduction are nitrous acid, nitrogen oxide and nitrogen dioxide. Below this value nitric oxide can be reduced in nitrous oxide. Thus the potential value is the most important parameter for the nitrogen oxides production selectivity. However, owing to the auto-catalytic character of the reduction mechanism, potential value can be controlled during intentiostatic industrial electrolysis. (author)

  9. Nitrosation and Nitration of Fulvic Acid, Peat and Coal with Nitric Acid

    Science.gov (United States)

    Thorn, Kevin A.; Cox, Larry G.

    2016-01-01

    Nitrohumic acids, produced from base extraction of coals and peats oxidized with nitric acid, have received considerable attention as soil ammendments in agriculture. The nitration chemistry however is incompletely understood. Moreover, there is a need to understand the reaction of nitric acid with natural organic matter (NOM) in general, in the context of a variety of environmental and biogeochemical processes. Suwannee River NOM, Suwannee River fulvic acid, and Pahokee Peat fulvic acid were treated with 15N-labeled nitric acid at concentrations ranging from 15% to 22% and analyzed by liquid and solid state 15N NMR spectroscopy. Bulk Pahokee peat and Illinois #6 coal were also treated with nitric acid, at 29% and 40% respectively, and analyzed by solid state 15N NMR spectroscopy. In addition to nitro groups from nitration of aromatic carbon, the 15N NMR spectra of all five samples exhibited peaks attributable to nitrosation reactions. These include nitrosophenol peaks in the peat fulvic acid and Suwannee River samples, from nitrosation of phenolic rings, and N-nitroso groups in the peat samples, from nitrosation of secondary amides or amines, the latter consistent with the peat samples having the highest naturally abundant nitrogen contents. Peaks attributable to Beckmann and secondary reactions of the initially formed oximes were present in all spectra, including primary amide, secondary amide, lactam, and nitrile nitrogens. The degree of secondary reaction product formation resulting from nitrosation reactions appeared to correlate inversely with the 13C aromaticities of the samples. The nitrosation reactions are most plausibly effected by nitrous acid formed from the reduction of nitric acid by oxidizable substrates in the NOM and coal samples. PMID:27175784

  10. Nitrosation and nitration of fulvic acid, peat and coal with nitric acid

    Science.gov (United States)

    Thorn, Kevin A.; Cox, Larry G.

    2016-01-01

    Nitrohumic acids, produced from base extraction of coals and peats oxidized with nitric acid, have received considerable attention as soil ammendments in agriculture. The nitration chemistry however is incompletely understood. Moreover, there is a need to understand the reaction of nitric acid with natural organic matter (NOM) in general, in the context of a variety of environmental and biogeochemical processes. Suwannee River NOM, Suwannee River fulvic acid, and Pahokee Peat fulvic acid were treated with 15N-labeled nitric acid at concentrations ranging from 15% to 22% and analyzed by liquid and solid state 15N NMR spectroscopy. Bulk Pahokee peat and Illinois #6 coal were also treated with nitric acid, at 29% and 40% respectively, and analyzed by solid state 15N NMR spectroscopy. In addition to nitro groups from nitration of aromatic carbon, the 15N NMR spectra of all five samples exhibited peaks attributable to nitrosation reactions. These include nitrosophenol peaks in the peat fulvic acid and Suwannee River samples, from nitrosation of phenolic rings, and N-nitroso groups in the peat samples, from nitrosation of secondary amides or amines, the latter consistent with the peat samples having the highest naturally abundant nitrogen contents. Peaks attributable to Beckmann and secondary reactions of the initially formed oximes were present in all spectra, including primary amide, secondary amide, lactam, and nitrile nitrogens. The degree of secondary reaction product formation resulting from nitrosation reactions appeared to correlate inversely with the 13C aromaticities of the samples. The nitrosation reactions are most plausibly effected by nitrous acid formed from the reduction of nitric acid by oxidizable substrates in the NOM and coal samples.

  11. Impact of scaling on the nitric-glycolic acid flowsheet

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. [Savannah River Site (SRS), Aiken, SC (United States)

    2016-02-01

    Savannah River Remediation (SRR) is considering using glycolic acid as a replacement for formic acid in Sludge Receipt and Adjustment Tank (SRAT) processing in the Defense Waste Processing Facility (DWPF). Catalytic decomposition of formic acid is responsible for the generation of hydrogen, a potentially flammable gas, during processing. To prevent the formation of a flammable mixture in the offgas, an air purge is used to dilute the hydrogen concentration below the 60% of the Composite Lower Flammability Limit (CLFL). The offgas is continuously monitored for hydrogen using Gas Chromatographs (GCs). Since formic acid is much more volatile and toxic than glycolic acid, a formic acid spill would lead to the release of much larger quantities to the environment. Switching from formic acid to glycolic acid is expected to eliminate the hydrogen flammability hazard leading to lower air purges, thus downgrading of Safety Significant GCs to Process Support GCs, and minimizing the consequence of a glycolic acid tank leak in DWPF. Overall this leads to a reduction in process operation costs and an increase in safety margin. Experiments were completed at three different scales to demonstrate that the nitric-glycolic acid flowsheet scales from the 4-L lab scale to the 22-L bench scale and 220-L engineering scale. Ten process demonstrations of the sludge-only flowsheet for SRAT and Slurry Mix Evaporator (SME) cycles were performed using Sludge Batch 8 (SB8)-Tank 40 simulant. No Actinide Removal Process (ARP) product or strip effluent was added during the runs. Six experiments were completed at the 4-L scale, two experiments were completed at the 22-L scale, and two experiments were completed at the 220-L scale. Experiments completed at the 4-L scale (100 and 110% acid stoichiometry) were repeated at the 22-L and 220-L scale for scale comparisons.

  12. Impact of scaling on the nitric-glycolic acid flowsheet

    International Nuclear Information System (INIS)

    Savannah River Remediation (SRR) is considering using glycolic acid as a replacement for formic acid in Sludge Receipt and Adjustment Tank (SRAT) processing in the Defense Waste Processing Facility (DWPF). Catalytic decomposition of formic acid is responsible for the generation of hydrogen, a potentially flammable gas, during processing. To prevent the formation of a flammable mixture in the offgas, an air purge is used to dilute the hydrogen concentration below the 60% of the Composite Lower Flammability Limit (CLFL). The offgas is continuously monitored for hydrogen using Gas Chromatographs (GCs). Since formic acid is much more volatile and toxic than glycolic acid, a formic acid spill would lead to the release of much larger quantities to the environment. Switching from formic acid to glycolic acid is expected to eliminate the hydrogen flammability hazard leading to lower air purges, thus downgrading of Safety Significant GCs to Process Support GCs, and minimizing the consequence of a glycolic acid tank leak in DWPF. Overall this leads to a reduction in process operation costs and an increase in safety margin. Experiments were completed at three different scales to demonstrate that the nitric-glycolic acid flowsheet scales from the 4-L lab scale to the 22-L bench scale and 220-L engineering scale. Ten process demonstrations of the sludge-only flowsheet for SRAT and Slurry Mix Evaporator (SME) cycles were performed using Sludge Batch 8 (SB8)-Tank 40 simulant. No Actinide Removal Process (ARP) product or strip effluent was added during the runs. Six experiments were completed at the 4-L scale, two experiments were completed at the 22-L scale, and two experiments were completed at the 220-L scale. Experiments completed at the 4-L scale (100 and 110% acid stoichiometry) were repeated at the 22-L and 220-L scale for scale comparisons.

  13. Chemistry of tributyl phosphate and nitric acid at constant volume

    International Nuclear Information System (INIS)

    This paper addresses the reaction of tributyl phosphate (TBP) with nitric acid (HNO3). The reaction pressure of TBP/HNO3 mixtures as a function of time was measured under constant volume. A simplified model, which parametrically includes autocatalysis, was used to plot the total gas production of the reaction as a function of time. Comparison of the functions shows a rough equivalence in the induction time, reaction time, and total gas production. Predictions of the amounts of reaction products as a function of time were made based on assumptions regarding autocatalysis and using rate constants from experimental data. The derived reaction mechanisms and experimental results have several implications. Tests with a large amount of venting and high surface to volume ratio will show very different behavior than tests with increasing confinement and low surface to volume ratios. The amount alkyl nitrate, carbon monoxide, or hydrogen that reacts within the organic phase is limited by their solubilities and volatilities. The overall yield of both heat and gas per mol of nitric acid or TBP will vary significantly depending on the amount of solution, free volume, and vessel vent capacity

  14. Safe conditions for contacting nitric acid or nitrates with tri-n-butyl phosphate (TBP)

    Energy Technology Data Exchange (ETDEWEB)

    Hyder, M.L

    1994-01-01

    In response to a request from DOE-SR, the current state of knowledge of the reactions between TBP and aqueous nitrate solutions is critically reviewed, and recommendations are made for the safe operation of SRS separations equipment in which this combination of chemicals may be present. The existing limits for evaporation are validated. Guidelines are presented for cases in which general limits do not apply. The rate of reaction between nitric acid and TBP appears to be controlled by the rate of TBP hydrolysis. The hydrolysis reaction produces dibutyl phosphate and n-butanol. The hydrolysis rate is a strong function of temperature, and becomes very fast at temperatures in the range 130{degrees} to 150{degrees}C. The resulting n-butanol is volatile at high temperatures, boiling at 117.5{degrees}C, but is also subject to exothermic oxidation by nitric acid or nitrates. If oxidation occurs before the n-butanol evaporates, the heat of oxidation may exceed local cooling by convection. The resulting heating will further accelerate the reaction, leading to an energetic runaway and possibly (in confined systems) an explosion. Extensive experiments and practice have shown that in a well-mixed and well-vented aqueous system such as an evaporator, at moderate acidities and temperatures below 130{degrees}C, the heat of reaction is adequately removed by vaporization of steam. In general, the heating will be so slow that natural processes provide adequate cooling at temperatures below 80{degrees}C. Above this temperature, care should be taken to ensure that adequate cooling is available for the amount of TBP that may be present. Experiments suggest that in well-ventilated systems n-butanol evaporation and convective cooling are sufficient to control the reaction at temperatures up to 120{degrees}C.

  15. Safe conditions for contacting nitric acid or nitrates with tri-n-butyl phosphate (TBP)

    International Nuclear Information System (INIS)

    In response to a request from DOE-SR, the current state of knowledge of the reactions between TBP and aqueous nitrate solutions is critically reviewed, and recommendations are made for the safe operation of SRS separations equipment in which this combination of chemicals may be present. The existing limits for evaporation are validated. Guidelines are presented for cases in which general limits do not apply. The rate of reaction between nitric acid and TBP appears to be controlled by the rate of TBP hydrolysis. The hydrolysis reaction produces dibutyl phosphate and n-butanol. The hydrolysis rate is a strong function of temperature, and becomes very fast at temperatures in the range 130 degrees to 150 degrees C. The resulting n-butanol is volatile at high temperatures, boiling at 117.5 degrees C, but is also subject to exothermic oxidation by nitric acid or nitrates. If oxidation occurs before the n-butanol evaporates, the heat of oxidation may exceed local cooling by convection. The resulting heating will further accelerate the reaction, leading to an energetic runaway and possibly (in confined systems) an explosion. Extensive experiments and practice have shown that in a well-mixed and well-vented aqueous system such as an evaporator, at moderate acidities and temperatures below 130 degrees C, the heat of reaction is adequately removed by vaporization of steam. In general, the heating will be so slow that natural processes provide adequate cooling at temperatures below 80 degrees C. Above this temperature, care should be taken to ensure that adequate cooling is available for the amount of TBP that may be present. Experiments suggest that in well-ventilated systems n-butanol evaporation and convective cooling are sufficient to control the reaction at temperatures up to 120 degrees C

  16. REE and TPE sorption on strong-acid sulfocation exchanger KU-2 from nitric acid solutions

    International Nuclear Information System (INIS)

    Sorption of rare earths on strong acid sulfocationite KU-2, depending on solution acidity (0.1-2.0 mol/l nitric acid) and rare earths concentration, has been studied. It is ascertained that in solutions concentrated in terms of nitrate-ions, where formation of M(NO3)2+ and M(NO3)2+ complexes is possible, a seeming increase in the ionite capacity by approximately 20% is observed. 3 refs.; 1 fig.; 5 tabs

  17. A method for concentrating organic dyes: colorimetric measurements of nitric oxides and sialic acids.

    Science.gov (United States)

    Lalezari, Parviz; Lekhraj, Rukmani; Casper, Diana

    2011-09-01

    A new method for extraction and concentration of organic dyes that uses a reagent composed of a nonionic detergent mixed with an alcohol is described. We have observed that water-soluble organic dyes are also soluble in nonionic detergents and can be extracted by adding salt, which separates the dye-detergent component from the aqueous phase. We have also found that mixing nonionic detergents with alcohols markedly reduces their viscosity and produces stable, free-flowing, and effective reagents for color extraction. On the basis of these observations, we used a mixture of Triton X-100 and 1-butanol and observed that water-soluble natural and synthetic chromophores, as well as dyes generated in biochemical reactions, can be extracted, concentrated, and analyzed spectrophotometrically. Trypan blue and phenol red are used as examples of synthetic dyes, and red wine is used as an example of phenolic plant pigments. Applications for quantification of nitric oxides and sialic acids are described in more detail and show that as little as 0.15 nmol of nitric oxide and 0.20 nmol of sialic acid can be detected. A major advantage of this method is its ability to concentrate chromophores from dye-containing solutions that otherwise cannot be measured because of their low concentrations. PMID:21605540

  18. Modelling of uranyl nitrate and nitric acid extraction in diluted TBP using Chem-Unifac

    International Nuclear Information System (INIS)

    Chem-UNIFAC model is applied to TBP/dodecane/water/UO2(NO3)2 and TBP/dodecane/water/HNO3 systems, following our previous studies on TBP/diluent (alkane, HCCl3, CCl4) and TBP/diluent/water/salting out agent (same diluents) systems. New Chem-UNIFAC parameters for TBP/water pair are calculated and an unique set of parameters is proposed to describe the TBP/dodecane/water/UO2(NO3)2 system, for a wide range of TBP/diluent volume proportions (10%, 30%, 50%, 100%) and a wide range of uranyl nitrate aqueous concentration. Nitric acid and water extraction in TBP/dodecane/water/HNO3 is also calculated and an improvement is found in the description of the corresponding isotherms. (authors)

  19. Recovery of Lead from Sulfide Concentrate after Mechanochemical Activation Using Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    A.G.Kholmogorov; O.N.Kononova; G.L.Pashkov; L.V.Shashina; V.P.Plekhanov; A.A.Sabetskiy

    2005-01-01

    Decomposition of lead sulfide concentrates in nitric acidic solutions after ferric (Ⅲ) nitrate addition and mechanical preparation has been investigated. It was found out that the decomposition can be achieved in HNO3 solution (>1.5 mol·L-1) at the temperature above 85℃. The leaching rate of lead can be increased by means of mechanochemical activation. The use of [Fe(NO3)3-HNO3-H2O] aqueous salt system allows the decomposition of lead sulfide concentrate at room temperature and in this case the concentration of HNO3 does not exceed 0.05-0.1 mol.L-1, The degree of lead recovery into solution from PbS concentrate reaches 99.3%-99.6c70 with the mechanochemical activation of this concentrate. The insoluble residues after the leaching contain SiO2, S0, FeCO3 and PbSO4.

  20. Delayed effects of inhaled nitric acid aerosols in the rat: preliminary studies

    International Nuclear Information System (INIS)

    Rats that inhaled transuranic nitrate aerosols in a toxicology study were simultaneously exposed to aerosols of the suspending solution, nitric acid. Results indicated that exposure to nitric acid was associated with the finding of bone tumors. Other rats, exposed to low levels of inhaled Pu(NO3)4, showed one osteosarcoma in 79 rats examined

  1. Research on the Stability of Dimethyl Hydroxylamine-methyl Hydrazinein Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By the means of the comparison of the extraction of PU(Ⅲ) and plutonium in nitric acid mediumcontaining dimethyl hydroxylamine-methyl hydrazine and the analysis of the percent content of PU(Ⅳ) inthe system, the stability of dimethyl hydroxylamine-methyl hydrazine in nitric acid medium is

  2. Transportation impact analysis for the shipment of low specific activity nitric acid. Revisison 1

    International Nuclear Information System (INIS)

    This is in support of the Plutonium-Uranium Extraction (PUREX) Facility Low Specific Activity (LSA) Nitric Acid Shipment Environmental Assessment. It analyzes potential toxicological and radiological risks associated with transportation of PUREX Facility LSA Nitric Acid from the Hanford Site to Portsmouth VA, Baltimore MD, and Port Elizabeth NJ

  3. Transportation impact analysis for the shipment of low specific activity nitric acid. Revisison 1

    Energy Technology Data Exchange (ETDEWEB)

    Green, J.R.

    1995-05-16

    This is in support of the Plutonium-Uranium Extraction (PUREX) Facility Low Specific Activity (LSA) Nitric Acid Shipment Environmental Assessment. It analyzes potential toxicological and radiological risks associated with transportation of PUREX Facility LSA Nitric Acid from the Hanford Site to Portsmouth VA, Baltimore MD, and Port Elizabeth NJ.

  4. TBP 20% - diluent/HNO3/H2O liquid-liquid extraction system: equilibrium normalization data of nitric acid, ruthenium and zirconium

    International Nuclear Information System (INIS)

    The extraction behaviour of nitric acid, nitrosyl-ruthenium nitrate and zirconium hydroxide nitrate in the system tri-n-butyl phosphate (TBP) 20% - diluent was studied. The main purpose was to obtain enough data to elaborate process flowsheets for the treatment of irradiated uranium fuels. During the runs, the equilibrium diagrams of nitric acid, ruthenium and zirconium were settled. From the achieved data, the influence of nitric acid, ruthenium, zirconium and nitrate ions concentration in the aqueous phase was checked. Furthermore, the density and the surface tension of the aqueous and organic phases were determined, gathering the interfacial tension after the contact between the phases. A comparison among the obtained equilibrium data and the existing one from literature allowed the elaboration of mathematical models to express the distribution behaviour of nitric acid, ruthenium and zirconium as a function of nitrate ions concentration in the aqueous phase. The reduction of TBP concentration from 30% v/v (normally used) to 20% v/v, has shown no influence in the extraction behaviour of the elements. A decreasing in the distribution values was observed and that means an important factor during the decontamination of uranium from its contaminants, ruthenium and zirconium. (Author)

  5. PC-88A - impregnated polymeric beads. Preparation, characterization and application for extraction of Pu(IV) from nitric acid medium

    International Nuclear Information System (INIS)

    The extractant-impregnated polymeric beads (EIPBs), containing polyethersulfone as base polymer and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) as an extractant, were prepared by phase inversion method. These EIPBs were characterized by FTIR, TGA and SEM techniques. The beads were found to have excellent acid stability, since these did not exhibit any structural deformation or loss of the extractant into aqueous nitric acid solution (6 M), for a period of 15 d. The feasibility of Pu(IV) extraction, using these beads, from nitric acid solution was tested by batch equilibration method. Parametric dependence of Pu(IV) extraction on experimental variables, like strength of nitric acid, equilibration time, Pu(IV) concentration, etc., was investigated. The present study also addressed the important practical issues, like maximum loading capacity and the reusability of these beads. Under optimized conditions, equilibrium capacity and maximum loading capacity for Pu(IV) were found to be 2.03 and 7.50 mg per gram of the swollen beads, respectively. The reusability of the beads was also ascertained by repetitive extraction-stripping of Pu(IV) up to 7 cycles of operation, without significant change in their extraction performance. The extraction of Pu(IV) by the blank polymeric beads was observed to be almost negligible, under the similar experimental conditions. (orig.)

  6. Airborne measurements of the nitric acid partitioning in persistent contrails

    Directory of Open Access Journals (Sweden)

    Th. Peter

    2009-11-01

    Full Text Available This study reports the first systematic measurements of nitric acid (HNO3 uptake in contrail ice particles at typical aircraft cruise altitudes. During the CIRRUS-III campaign cirrus clouds and almost 40 persistent contrails were probed with in situ instruments over Germany and Northern Europe in November 2006. Besides reactive nitrogen, water vapor, cloud ice water content, ice particle size distributions, and condensation nuclei were measured during 6 flights. Contrails with ages up to 12 h were detected at altitudes 10–11.5 km and temperatures 211–220 K. These contrails had a larger ice phase fraction of total nitric acid (HNO3ice/HNO3tot = 6% than the ambient cirrus layers (3%. On average, the contrails contained twice as much HNO3ice as the cirrus clouds, 14 pmol/mol and 6 pmol/mol, respectively. Young contrails with ages below 1 h had a mean HNO3ice of 21 pmol/mol. The contrails had higher nitric acid to water molar ratios in ice and slightly higher ice water contents than the cirrus clouds under similar meteorological conditions. The differences in ice phase fractions and molar ratios between developing contrails and cirrus are likely caused by high plume concentrations of HNO3 prior to contrail formation. The location of the measurements in the upper region of frontal cirrus layers might account for slight differences in the ice water content between contrails and adjacent cirrus clouds. The observed dependence of molar ratios as a function of the mean ice particle diameter suggests that ice-bound HNO3 concentrations are controlled by uptake of exhaust HNO3 in the freezing plume aerosols in young contrails and subsequent trapping of ambient HNO3 in growing ice particles in older (age > 1 h contrails.

  7. Airborne measurements of the nitric acid partitioning in persistent contrails

    Directory of Open Access Journals (Sweden)

    D. Schäuble

    2009-06-01

    Full Text Available This study reports the first systematic measurements of nitric acid (HNO3 uptake in contrail ice particles at typical aircraft cruise altitudes. During the CIRRUS-III campaign cirrus clouds and almost 40 persistent contrails were probed with in situ instruments over Germany and Northern Europe in November 2006. Besides reactive nitrogen, water vapor, cloud ice water content, ice particle size distributions, and condensation nuclei were measured during 6 flights. Contrails with ages up to 8 hours were detected at altitudes 10–11.5 km and temperatures 211–220 K. These contrails had a larger ice phase fraction of total nitric acid (HNO3ice/HNO3tot = 6% than the ambient cirrus layers (3%. On average, the contrails contained twice as much HNO3ice as the cirrus clouds, 14 pmol/mol and 6 pmol/mol, respectively. Young contrails with ages below 1 h had a mean HNO3ice of 21 pmol/mol. The contrails had higher nitric acid to water molar ratios in ice and slightly higher ice water contents than the cirrus clouds under similar meteorological conditions. The differences in ice phase fractions and molar ratios between developing contrails and cirrus are likely caused by high plume concentrations of HNO3 prior to contrail formation. The location of the measurements in the top region of frontal cirrus layers might account for slight differences in the ice water content between contrails and adjacent cirrus clouds. The observed dependence of molar ratios as a function of the mean ice particle diameter suggests that ice-bound HNO3 concentrations are controlled by uptake of exhaust HNO3 in the freezing plume aerosols in young contrails and subsequent trapping of ambient HNO3 in growing ice particles in older (age > 1 h contrails.

  8. Extraction of uranium from nitric acid solutions by tributylphosphate/kerosene

    International Nuclear Information System (INIS)

    The extraction of nitric acid and hexavalent uranium from nitric acid and nitric acid containing uranium(VI) media by tributylphosphate (TBP)/kerosene has been studied, and all factors affecting the extraction process (time of mixing, uranium concentration, nitric acid concentration, TBP concentration, temperature) have been investigated. The equilibrium constant of the extraction reaction of uranium by TBP was found to be 102.464, 102.668 L4/mol4 at 25 C, and the enthalpy was -16.47, -23.07 k.J/mol for 0.5 M and 1 M nitric acid concentration respectively. The optimal conditions obtained from this study were applied on the purification of the Yellow cake resulted as a byproduct from the Pilot Plant of H3PO4 purification in the TSP fertilizer company in Homs. (Authors)

  9. Extraction of palladium from nitric acid medium by commercial resins with phosphinic acid, methylene thiol and isothiouronium moieties attached to polystyrene-divinylbenzene

    International Nuclear Information System (INIS)

    Commercially available polystyrene-divinylbenzene (PS-DVB) resins functionalized with isothiouronium (Tulsion CH-95), phosphinic acid (Tulsion CH-96) and methylene thiol (Tulsion CH-97) moieties have been used for separating palladium from nitric acid medium. Extraction of palladium has been studied as a function of time, concentration of nitric acid and palladium. The distribution coefficients (Kd, ml/g) of palladium on sulfur based resins (Tulsion CH-95 and Tulsion CH-97) are higher (5000-104 ml/g in 0.1M nitric acid) than on Tulsion CH-96 resin and decrease with increasing concentration of nitric acid. The initial rate of extraction of palladium by Tulsion CH-95 and Tulsion CH-97 resins was very rapid and the time required for the establishment of equilibrium was a function of palladium concentration in the aqueous phase. The rate data could be fitted by a second order rate equation and the magnitude of rate constant for the extraction of palladium by these resins (∼102M-1 x min-1) decreased in the order of: Tulsion CH-95 > Tulsion CH-97 > Tulsion CH-96. The extraction isotherms of Tulsion CH-95 were fitted by Langmuir adsorption model and the coefficients were obtained by regression. The extraction capacity of palladium on Tulsion CH-95 was found to be ∼20 mg/g at 3M nitric acid. Column experiments have been conducted and the data were fitted using Thomas model. A column utilization of 75% was achieved for the extraction of palladium by Tulsion CH-95 resin. (author)

  10. Method of separating multi-ingredient mixed nitric acid solution

    International Nuclear Information System (INIS)

    A multi-ingredient mixed nitric acid solution as high level liquid wastes is heated to a temperature higher than the denitrification temperature at which transuranium elements are converted from the form of nitrate compounds to oxides, and then water is added. The transuranium elements are converted into water insoluble oxides. On the contrary, since nuclides of fission products having extremely high denitrification temperatures are left in the form of nitrates as they are even after the heating and they are dissolved in water, only the transuranium elements can be easily separated. The solution selectively separated and removed only with the transuranium elements having long half decay times are vitrified by a usual method. Accordingly, the storage period of the vitrification products is extremely shortened, to improve the processing safety. (T.M.)

  11. Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defense pathways

    OpenAIRE

    Mur, Luis A. J.; Prats, Elena; Pierre, Sandra; Hall, Michael A.; Hebelstrup, Kim H

    2013-01-01

    Plant defense against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defense responses to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signaling pathways but no attempt has been made to integrate NO in...

  12. Chemical species of fission product ruthenium in the solution of irradiated uranium dioxide in nitric acid

    International Nuclear Information System (INIS)

    High performance liquid chromatography was applied to separate the ruthenium species in the solution of irradiated uranium dioxide in 1 N nitric acid. The separation column was made of a strongly acidic cation exchanger of sulfonic acid type in a Teflon tube. In order to avoid interconversion of the species during separation, elution of the species was performed by 1 N nitric acid without changing the concentration of nitric acid. With this method, not only cationic species but also anionic and neutral species were separated from each other with good resolution. More than 24 chemical species of ruthenium were separated. The ionic valences of the species were determined from their cation and anion exchange behavior in nitric acid. The main species were four anionic species, six neutral species, seven monovalent cations, three divalent cations and four trivalent cations. The relative abundance of the species was determined as a function of elapsed time from the dissolution of irradiated uranium dioxide. Equilibrium between the species was not established even a half-year after dissolution of the irradiated uranium dioxide in nitric acid solution. The extractabilities of the species were determined for a 100% TBP Tri-n-butyl phosphate)-1N nitric acid system. Four of them, two anionic apcies and two monovalent cations in the nitric acid solution, were extracted appreciably by TBP. (orig.)

  13. 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…

  14. Buffer capacities of podzolic and peat gleyic podzolic soils to sulfuric and nitric acids

    Science.gov (United States)

    Kuznetsov, N. B.; Alekseeva, S. A.; Shashkova, G. V.; Dronova, T. Ya.; Sokolova, T. A.

    2007-04-01

    Soil samples from the main genetic horizons of pale podzolic and peat gleyic podzolic soils from the Central Forest Reserve were subjected to a continuous potentiometric titration by sulfuric and nitric acids. The sulfate sorption capacity was determined in soil mineral horizons. The buffer capacity of mineral horizons of both soils to sulfuric acid was found to be higher than that to the nitric acid. This is explained by the sorption of sulfates via the mechanism of ligand exchange with the release of hydroxyl groups from the surfaces of Fe and Al hydroxide particles and edge faces of clay crystallites. The buffer capacity of organic horizons of the pale podzolic soil to sulfuric acid proved to be higher than that to nitric acid; in organic horizons of the peat gleyic podzolic soil, the buffer capacity to sulfuric acid was lower than that to nitric acid. The reasons for this phenomenon have yet to be investigated.

  15. The influence of nitric acid on the cloud processing of aerosol particles

    OpenAIRE

    Romakkaniemi, S.; Kokkola, H.; Lehtinen, K.E.J.; Laaksonen, A

    2006-01-01

    In this paper we present simulations of the effect of nitric acid (HNO3) on cloud processing of aerosol particles. Sulfuric acid (H2SO4) production and incloud coagulation are both affected by condensed nitric acid as nitric acid increases the number of cloud droplets, which will lead to smaller mean size and higher total surface area of droplets. As a result of increased cloud droplet number concentration (CDNC), the incloud coagulation rate is enhanced by a factor of 1–1.3, so that t...

  16. The relationship between cytokine level and nitric oxide content in aqueous humor after intraocular lens implantation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    AIM: To investigate the relationship between cytokine level and nitric oxide (NO) content in aqueous humor after intraocular lens implantation. METHODS: All New Zealand rabbits were divided randomly into three groups: (1) control group, (2) extracapsular cataract extraction group (ECCE), (3) extracapsular cataract extraction and posterior chamber intraocular lens implantation group (ECCE+IOL). The inflammation of all experimental rabbit eyes, including cornea edema and anterior chamber exudation were observed via zoom-photo slitlamp microscope 1,3,7,14,30 d postoperation. Meanwhile, aqueous humor was drawn for white blood cell (WBC) counting and classifying, and for NO-2/NO-3 and cytokine assay, including interleukin-2(IL-2), tumour necrosis factor-α(TNF-α). Statistics were taken by SPSS softwear. RESULTS: (1) Total WBC in aqueous humor were higher and anterior chamber exudation were more severe in ECCE+IOL group than that in ECCE group and control group. (2) The level of IL-2 and TNF-α and the content of NO-2/NO-3 in aqueous humor of ECCE+IOL group were higher than that in ECCE group and control group 1-14 d postoperation respectively, and it increased to peak value at 3-7 d postoperation and decreased gradually after two weeks postoperation. (3) The change regularity of IL-2, TNF-α and NO-2/NO-3 in each group were basically similar, i.e. when the level of cytokine (IL-2 and TNF-α) was normal, the content of NO-2/NO-3 was normal too, when the level of cytokine (IL-2 and TNF-α) increased, the content of NO-2/NO-3 increased too. CONCLUSION: The intraocular inflammation after ECCE+IOL was more severe than that after simple ECCE. NO, IL-2 and TNF-α play an important role in intraocular inflammation after intraocular lens implantation. The changes of IL-2 and TNF-α level was closely related with NO content in aqueous humor.

  17. Extraction of uranium(VI) and Thorium(IV) ions from nitric acid solutions by N,N,N',N'-tetrabutyladipicamide

    International Nuclear Information System (INIS)

    A new symmetrical diamide, the straight-chain alkyl substituted neutral tetrabutyladipicamide (TBAA) has been synthesized, characterized and used for the extraction of U(V) and Th(IV) from nitric acid solutions in a diluent composed of 50% 1,2,4-trimethylbenzene (TMB) and 50% kerosene (OK). Extraction distribution coefficients of (U(VI) and Th(IV) as a function of aqueous nitric acid concentration extractant concentration and temperature have been studied. Back-extraction of U(VI) and Th(IV) from organic phases by dilute nitric acid has been undertaken. From the data, the compositions of extracted species, equilibrium constants and enthalpies of extraction reactions have also been calculated. (author). 7 refs., 3 figs., 3 tabs

  18. Omega-3 fatty acids improve psychomotor performance via mechanism not related to nitric acid production

    Directory of Open Access Journals (Sweden)

    Marwan S. M. Al-Nimer

    2012-01-01

    Full Text Available Omega-3 fatty acids (ω-3FAs are essential polyunsaturated fats that protect the brain from cognitive impairment. It increases the activity of endothelial nitric oxide synthetase (eNOS and thereby increases the nitric acid (NO production. This study aimed to explore the effect of ω-3FAs on psychomotor performance and to relate this effect to the reactive nitrogen species. This study was conducted in Department of Pharmacology, College of Medicine, Al-Mustansiriya University in Baghdad, Iraq. Twenty healthy subjects, allocated randomly from medical college students, were participated in the single blind clinical trial. Participants were divided into two groups, each of ten subjects to receive either placebo or (ω-3FAs (750 mg single oral dose daily for 5 days. They were asked to perform psychomotor performance before and after 5 days of treatment, and venous blood was obtained for determination of serum nitric oxide (NO and peroxynitrite (ONOO. ω-3FAs treated group was significantly different from placebo-treated group in reducing choice and motor reaction times as well as the critical flicker frequency threshold. The serum levels of NO and ONOO in ω-3FAs-treated group did not significantly differ from placebo-treated group. Short term supplementation of ω-3FAs improves the psychomotor performance in young healthy subjects via a mechanism not related to the production of nitric oxide production. Inflorescence is a panicle few flowered and fruit is a capsule. The data of the results obtained were presented and discussed.

  19. Uptake of nitric acid by sub-micron-sized ice particles

    Science.gov (United States)

    Arora, O. P.; Cziczo, D. J.; Morgan, A. M.; Abbatt, J. P. D.; Niedziela, R. F.

    The uptake of gas phase nitric acid by half-micron-diameter ice crystals has been studied at 230 K by measuring the nitrate content of ice particles which have been exposed to 5 × 10-6 torr of nitric acid in a low temperature flow tube. A cold NaOH-coated denuder is used to distinguish gas-phase nitric acid from adsorbed nitric acid. Ice particle diameters were determined by fitting measured aerosol infrared extinction spectra to spectra calculated via Mie theory, and their number density is measured directly with a CN counter. Under conditions in which the surface is saturated and not all the gas-phase nitric acid adsorbs, the measured uptakes are 1.2 × 1014 molecules/cm² where the surface area is the geometric area of the particles. Within experimental uncertainties, this surface coverage is the same as that measured on thin films of ice formed by freezing liquid water. These results are the first quantitative study of the nitric acid uptake capacity of ice particles, and they provide additional support to the suggestion that ice and snow provide a route for the efficient scavenging of nitric acid from the atmosphere.

  20. Uptake of Gas-Phase Nitric Acid by Water-Ice Surfaces

    Science.gov (United States)

    Ullerstam, M.; Abbatt, J. P.

    2004-05-01

    Nitric acid is a widespread molecule found in the atmosphere. It is mainly removed from the troposphere by wet or dry deposition. In colder regions such as the upper troposphere and tropopause where cirrus clouds are formed nitric acid can also be scavenged by cirrus ice particles. The uptake of gas-phase nitric acid by water-ice films has been re-examined with a coated-wall flow tube coupled to a chemical-ionization mass spectrometer (CIMS) at 228K. Previous flow tube studies of this system have shown little dependence of the uptake over the partial pressure regime studied. In these studies the initial, short-term uptake has been the focus and the long term uptake has not been quantified. In this experimental setup it was possible to study the uptake of nitric acid at lower partial pressures resulting in a more atmospherically appropriate determination of the adsorption isotherm and the long term uptake has also been addressed. Measurement of the initial uptake coefficient representing a lower limit will also be presented. Finally, possible burial of nitric acid into the bulk of the ice during continuous growth of the ice film has been studied. In the atmosphere ice particles will be subject to cycles of evaporation and condensation which could cause the nitric acid to be encapsulated into the particle, especially since the major part of the adsorption has been proven to be irreversible. This could enhance the ice particles capacity of scavenging nitric acid.

  1. Effect of Nitric Acid Concentrations on Synthesis and Stability of Maghemite Nanoparticles Suspension

    Directory of Open Access Journals (Sweden)

    Irwan Nurdin

    2014-01-01

    Full Text Available Maghemite (γ-Fe2O3 nanoparticles have been synthesized using a chemical coprecipitation method at different nitric acid concentrations as an oxidizing agent. Characterization of all samples performed by several techniques including X-ray diffraction (XRD, transmission electron microscopy (TEM, alternating gradient magnetometry (AGM, thermogravimetric analysis (TGA, dynamic light scattering (DLS, and zeta potential. The XRD patterns confirmed that the particles were maghemite. The crystallite size of all samples decreases with the increasing concentration of nitric acid. TEM observation showed that the particles have spherical morphology with narrow particle size distribution. The particles showed superparamagnetic behavior with decreased magnetization values at the increasing concentration of nitric acid. TGA measurement showed that the stability temperature decreases with the increasing concentration of nitric acid. DLS measurement showed that the hydrodynamic particle sizes decrease with the increasing concentration of nitric acid. Zeta potential values show a decrease with the increasing concentration of nitric acid. The increasing concentration of nitric acid in synthesis of maghemite nanoparticles produced smaller size particles, lower magnetization, better thermal stability, and more stable maghemite nanoparticles suspension.

  2. Effect of nitric acid concentrations on synthesis and stability of maghemite nanoparticles suspension.

    Science.gov (United States)

    Nurdin, Irwan; Johan, Mohd Rafie; Yaacob, Iskandar Idris; Ang, Bee Chin

    2014-01-01

    Maghemite (γ-Fe2O3) nanoparticles have been synthesized using a chemical coprecipitation method at different nitric acid concentrations as an oxidizing agent. Characterization of all samples performed by several techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), alternating gradient magnetometry (AGM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta potential. The XRD patterns confirmed that the particles were maghemite. The crystallite size of all samples decreases with the increasing concentration of nitric acid. TEM observation showed that the particles have spherical morphology with narrow particle size distribution. The particles showed superparamagnetic behavior with decreased magnetization values at the increasing concentration of nitric acid. TGA measurement showed that the stability temperature decreases with the increasing concentration of nitric acid. DLS measurement showed that the hydrodynamic particle sizes decrease with the increasing concentration of nitric acid. Zeta potential values show a decrease with the increasing concentration of nitric acid. The increasing concentration of nitric acid in synthesis of maghemite nanoparticles produced smaller size particles, lower magnetization, better thermal stability, and more stable maghemite nanoparticles suspension. PMID:24963510

  3. Heterogeneous catalysis contribution for the denitration of aqueous nuclear radioactive waste with formic acid

    International Nuclear Information System (INIS)

    The chemical denitration aims to reduce the nitric acid concentration in nuclear fuel reprocessing aqueous wastes by adding formic acid as a reducing agent. The denitration reaction exhibits an induction period, which duration is related to the time needed by the key intermediate of the reaction, i.e. nitrous acid, to reach a threshold concentration in the reaction medium. The addition of a Pt/SiO2 catalyst in the reaction mixture suppresses the induction period of the chemical denitration. The aim of the present work is to identify the role of Pt/SiO2 in the catalytic denitration mechanism. The experimental work is based on the comparison of catalytic tests performed with various catalysts, in order to identify the intrinsic characteristics of Pt/SiO2 that might influence its activity for the reaction. Catalytic denitration results show that Pt/SiO2 acts only by speeding up the nitrous acid generation in the solution until its concentration reaches the threshold level of 0,01 mol L-1 in the experimental conditions. Catalysts activity is evaluated by quantifying the nitrous acid generated on the platinum surface during the induction period of the homogeneous denitration reaction. The large platinum aggregates reactivity is greater than the one of nano-sized particles. The study of the key step of the catalytic denitration reaction, the catalytic generation of nitrous acid, clarifies the role of Pt/SiO2. The homogeneous denitration is initiated thanks to a redox cycle on the catalyst surface: an initial oxidation of Pt0 by nitric acid, which is reduced into nitrous acid, followed by the reduction of the passivated 'Ptox' by formic acid. Furthermore, a platinum reduction by formic acid prior to the catalytic test prevents any platinum leaching from the catalyst into the nitric solution, being all the more significant as platinum dispersion is high. (author)

  4. Thermal Hazard Evaluation of Lauroyl Peroxide Mixed with Nitric Acid

    Directory of Open Access Journals (Sweden)

    Chi-Min Shu

    2012-07-01

    Full Text Available Many thermal runaway incidents have been caused by organic peroxides due to the peroxy group, –O–O–, which is essentially unstable and active. Lauroyl peroxide (LPO is also sensitive to thermal sources and is incompatible with many materials, such as acids, bases, metals, and ions. From the thermal decomposition reaction of various concentrations of nitric acid (HNO3 (from lower to higher concentrations with LPO, experimental data were obtained as to its exothermic onset temperature (T0, heat of decomposition (ΔHd, isothermal time to maximum rate (TMRiso, and other safety parameters exclusively for loss prevention of runaway reactions and thermal explosions. As a novel finding, LPO mixed with HNO3 can produce the detonation product of 1-nitrododecane. We used differential scanning calorimetry (DSC, thermal activity monitor III (TAM III, and gas chromatography/mass spectrometer (GC/MS analyses of the reactivity for LPO and itself mixed with HNO3 to corroborate the decomposition reactions and reaction mechanisms in these investigations.

  5. Thermal hazard evaluation of lauroyl peroxide mixed with nitric acid.

    Science.gov (United States)

    Tsai, Lung-Chang; You, Mei-Li; Ding, Mei-Fang; Shu, Chi-Min

    2012-01-01

    Many thermal runaway incidents have been caused by organic peroxides due to the peroxy group, -O-O-, which is essentially unstable and active. Lauroyl peroxide (LPO) is also sensitive to thermal sources and is incompatible with many materials, such as acids, bases, metals, and ions. From the thermal decomposition reaction of various concentrations of nitric acid (HNO3) (from lower to higher concentrations) with LPO, experimental data were obtained as to its exothermic onset temperature (T0), heat of decomposition (ΔHd), isothermal time to maximum rate (TMRiso), and other safety parameters exclusively for loss prevention of runaway reactions and thermal explosions. As a novel finding, LPO mixed with HNO3 can produce the detonation product of 1-nitrododecane. We used differential scanning calorimetry (DSC), thermal activity monitor III (TAM III), and gas chromatography/mass spectrometer (GC/MS) analyses of the reactivity for LPO and itself mixed with HNO3 to corroborate the decomposition reactions and reaction mechanisms in these investigations. PMID:22763742

  6. Bile acids increase intracellular Ca2+ concentration and nitric oxide production in vascular endothelial cells

    OpenAIRE

    Nakajima, Toshiaki; Okuda, Yukichi; Chisaki, Keigo; Shin, Wee-Soo; Iwasawa, Kuniaki; Morita, Toshihiro; Matsumoto, Akihiro; Suzuki, Jun-ichi; Suzuki, Seizi; Yamada, Nobuhiro; Toyo-Oka, Teruhiko; Nagai, Ryozo; Omata, Masao

    2000-01-01

    The effects of bile acids on intracellular Ca2+ concentration [Ca2+]i and nitric oxide production were investigated in vascular endothelial cells.Whole-cell patch clamp techniques and fluorescence measurements of [Ca2+]i were applied in vascular endothelial cells obtained from human umbilical and calf aortic endothelial cells. Nitric oxide released was determined by measuring the concentration of NO2−.Deoxycholic acid, chenodeoxycholic acid and the taurine conjugates increased [Ca2+]i concent...

  7. Nitric Acid-Treated Carbon Fibers with Enhanced Hydrophilicity for Candida tropicalis Immobilization in Xylitol Fermentation

    OpenAIRE

    Le Wang; Na Liu; Zheng Guo; Dapeng Wu; Weiwei Chen; Zheng Chang; Qipeng Yuan; Ming Hui; Jinshui Wang

    2016-01-01

    Nitric acid (HNO3)-treated carbon fiber (CF) rich in hydrophilic groups was applied as a cell-immobilized carrier for xylitol fermentation. Using scanning electron microscopy, we characterized the morphology of the HNO3-treated CF. Additionally, we evaluated the immobilized efficiency (IE) of Candida tropicalis and xylitol fermentation yield by investigating the surface properties of nitric acid treated CF, specifically, the acidic group content, zero charge point, degree of moisture and cont...

  8. Study on reduction and back extraction of Pu(IV) by urea derivatives in nitric acid conditions

    International Nuclear Information System (INIS)

    The reduction kinetics of Pu(IV) by hydroxyl-semicarbazide (HSC), hydroxyurea (HU) and di-hydroxyurea (DHU) in nitric acid solutions were investigated separately with adequate kinetic equations. In addition, counter-current cascade experiments were conducted for Pu split from U in nitric acid media using three kinds of reductant, respectively. The results show that urea derivatives as a kind of novel salt-free reductant can reduce Pu(IV) to Pu(III) rapidly in the nitric acid solutions. The stripping experimental results showed that Pu(IV) in the organic phase can be stripped rapidly to the aqueous phase by the urea derivatives, and the separation factors of plutonium /uranium can reach more than 104. This indicates that urea derivatives is a kind of promising salt-free agent for uranium/plutonium separation. In addition, the complexing effect of HSC with Np(IV) was revealed, and Np(IV) can be back-extracted by HSC with a separation factor of about 20

  9. Studies on photolysis of nitrosyl ruthenium complexes in nitric acid media

    International Nuclear Information System (INIS)

    The photolysis of nitrosyl ruthenium complexes in nitric acid media has been investigated in detail using low pressure mercury lamp (254 nm). The UV spectra of nitrosyl ruthenium complexes is also studied. The experimental results show that the photolysis of nitrosyl ruthenium in nitric acid media obeys pseudo-first order kinetics. The rate constant is affected by the concentration of nitric acid and has a maximum at 2 mol/L HNO3. In temperature range from 10 degree C to 40 degree C, the rate constant decreases with the increasing of the temperature

  10. Study of the sorption of nitric acid by carbons with a varying graphitization rate

    International Nuclear Information System (INIS)

    After having recalled some aspects of the crystalline structure of graphite, and the classification and main properties of lamellar complexes, the author of this research thesis outlines that the graphite-nitric acid complex belongs to the category of spontaneous lamellar complexes which are notably unsteady, or remain steady in presence of an excess of reactant. Then, this research thesis reports the study of the reaction of nitric acid on graphite as well as on pre-graphitic and partially graphitized carbons. The objective is to relate the carbon structure status to its reactivity with respect to nitric acid, and to study the evolution of this reactivity as graphitization progresses

  11. A study on the dissolution of uranium compounds(UO2, AUC) in nitric acid solutions

    International Nuclear Information System (INIS)

    The dissolution behavior of UO2 and AUC powder in nitric acid solutions was investigated to evaluate the performance of chemical decontamination process applicable to and internal surface of metallic system components such as tanks and piping in the uranium conversion plant. It was revealed that the dissolution of UO2 in nitric acid solutions containing low concentration of H2O2 was more effective than that in nitric acid solution without H2O2 as one of the conventional inorganic acid decontamination processes. AUC powder dissolved easily and continuously in nitric acid solutions before the solution pH attains about 3, but above that solution pH uranium concentration in the solution was lowered drastically by recrystallization. It was convinced that pH range of 2.5 ∼ 3 is desired in the decontamination of surface contaminated with AUC

  12. Stimulation of nitric oxide synthesis by the aqueous extract of Panax ginseng root in RAW 264.7 cells

    OpenAIRE

    Friedl, Roswitha; Moeslinger, Thomas; Kopp, Brigitte; Spieckermann, Paul Gerhard

    2001-01-01

    In this study, we investigated the effect of Panax ginseng root aqueous extracts upon inducible nitric oxide synthesis in RAW 264.7 cells. Panax ginseng root extract has been used in the Asian world for centuries as a traditional herb to enhance physical strength and resistance and is becoming more and more popular in Europe and North America.Incubation of murine macrophages (RAW 264.7 cells) with increasing amounts of aqueous extracts of Panax ginseng (0.05 – 0.8 μg μl−1) showed a dose depen...

  13. Interactions of nitric oxide with copper(II) dithiocarbamates in aqueous solution.

    Science.gov (United States)

    Díaz, Alicia; Ortiz, Mayreli; Sánchez, Ileana; Cao, Roberto; Mederos, Alfredo; Sanchiz, Joaquin; Brito, Felipe

    2003-07-01

    This is the first report on the formation of air-stable copper nitrosyl complexes. The interaction of nitric oxide, NO, with Cu(DTC)(2).3H(2)O (DTC: dithiocarbamate) and was studied in aqueous solution at pH 7.4 and 293 K. The stability constants were determined from UV-Vis data, using LETAGROP program. The high values obtained, log beta(1)=9.743(5) and log beta(2)=15.44(2) for Cu(ProDTC)(2)-NO, (ProDTC=L-prolinedithiocarbamate) and log beta(1)=8.723(5) and log beta(2)=11.45(2) for Cu(MorDTC)(2)-NO system, (MorDTC=morpholyldithiocarbamate), indicate the formation of two stable nitrosyl complexes, Cu(DTC)(2)NO and Cu(DTC)(2)(NO)(2). Coordinated NO is neither affected by the presence of air nor when the solution is purged with Ar. Cu(MorDTC)(2)NO.3H(2)O was isolated in the solid state and its nuNO (IR) band at 1682 cm(-1), but affected by temperature variations over 333 K. PMID:12818798

  14. Isothermal heat measurements of TBP-nitric acid solutions

    International Nuclear Information System (INIS)

    Net heats of reaction were measured in an isothermal calorimeter for TBP/HNO3 solutions at ambient pressure and temperatures above 100 degrees C. Carbon and nitrogen balances were performed giving the reaction stoichiometry. Rate expressions were derived and rate constants determined for both the single and two phase systems which included mass lost from the reacting system by evaporation. This mathematical model was fit to the experimental data (including the measured net heat and off-gas rate) gathered over a wide range of conditions. The oxidation rate constant was determined to be 5.4E-4 min-1 at 110 degrees C for an open open-quotes ventedclose quotes system as compared to >1E-3min-1 in a closed system. The heat released per unit material oxidized was also reduced due to a decrease in dissolved oxidants and an inefficient reduction of HNO3. Oxidation in the organic phase was found to be first order in nitric acid and pseudo-zero order in butylnitrate and water

  15. Study of the properties of dialkyl thiophosphoric acids. Application to the extraction of U, in phosphoric and nitric solutions

    International Nuclear Information System (INIS)

    A study is made of complex formation and liquid-liquid extraction of uranium (VI) by dialkyl-thiophosphoric acids of formula (RO)2POSH and by the synergic mixtures: dialkylthiophosphoric acids-phosphine oxides. The aqueous phases studied consist of concentrated phosphoric acid solutions and nitric acid solutions. Several methods, including distribution coefficient measurements, U.V., visible and infrared absorption spectrophotometries and magnetic resonance, were used to study the extraction mechanisms and the structures of species formed in the organic phase. The influence of different parameters (partition of extraction agent, dimerisation, acid ligand-phosphine oxide association, extraction of inorganic acids...) on the uranium (VI) distribution coefficients enabled the constants of complex formation in the aqueous phase and extraction in the organic phase to be determined. These various properties were compared with those of dialkyl phosphoric and dithiophosphoric acids. The mechanisms established prove that sulfur donors ligands form stable complexes with UO22+ ions although U(VI) is considered as a ''hard class a'' acceptor according to Ahrland's classification

  16. HIRDLS/Aura Level 3 Nitric Acid (HNO3) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Nitric Acid (HNO3) Zonal Fourier Coefficients" version 7 data product (H3ZFCHNO3) contains the entire mission (~3 years) of HIRDLS data...

  17. Time-resolved laser-induced fluorescence of UO22+ in nitric acid solutions

    International Nuclear Information System (INIS)

    A comparison between nitrogen and tripled Nd-YAG laser source for Time-Resolved Laser-Induced Fluorescence (TRLIF) of uranium in nitric acid solutions in the framework of on-line feasibility has been performed. Hence, for uranium on-line monitoring with fiber optics, nitrogen laser (337 nm), most usual source in TRLIF has several drawback; poor beam quality and non negligible nitric acid absorption at 337 nm. Tripled Nd-YAG laser (355 nm) despite lower uranium absorption coefficient has several advantages: no influence of nitric acid absorption, better beam quality, better fiber transmission and solid state technology. No significant difference for fluorescence spectra and lifetimes are observed for both lasers. Limit of detection for direct determination of uranium in nitric acid by TRLIF is in the μg/l (10-8 M) range for both lasers. (author)

  18. Fatigue crack propagation behaviors of zirconium and Ti-5Ta alloy in boiling nitric acid

    International Nuclear Information System (INIS)

    Fatigue crack propagation behaviors of zirconium (Zr) and titanium-5%tantalum (Ti-5Ta) alloy in boiling nitric acid were investigated by fatigue tests. The crack propagation rates (CPR) of them were measured as a function of the stress intensity factor range, ΔK. CPR of Zr in boiling nitric acid was markedly enhanced as compared with that in air at room temperature. On the other hand, any environmental acceleration effect and any fractographic difference were not observed in CPR tests of Ti-5Ta alloy. The fractograph of Zr tested in the nitric acid showed a river pattern type crack. The enhancement effect on CPR of Zr was interpreted with high susceptibility to stress corrosion cracking (SCC) in boiling nitric acid. (author)

  19. Critical evaluation of pressurized microwave-assisted digestion efficiency using nitric acid oxidizing systems (M7)

    International Nuclear Information System (INIS)

    Full text: The possibilities of enhancement of a medium-pressure microwave-assisted digestion system for sample preparation in trace element analysis of biological material was investigated. Based on optimal digestion conditions for oxidizing systems with nitric acid, different digestion procedures were examined to minimize residual carbon. The substitution of nitric acid and the addition of hydrogen peroxide and ozone to nitric acid was evaluated. The residual carbon content of the digestate was determined coulometrically. Addition of hydrogen peroxide during organic oxidation reactions does not lower the resolved carbon in the solution. Ozone was tested as an additional, potentially non-contaminating, digestion/oxidation system to the nitric acid used in the sample preparation method. (author)

  20. 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

  1. Extraction of nitric acid, technetium and palladium by bidentate carbamoylphosphonates

    Energy Technology Data Exchange (ETDEWEB)

    Gorski, B.; Kuca, L.; Petrzilova, H.

    1985-09-01

    The extraction of HNOsub(3), TcOsub(4)sup(-), and Pd by solutions of dibutyl N,N-diethylcarbomylmethylenephosphonate (DBDECMP) and dibutyl N,N-diethylcarbamoylphosphonate (DBDECP) in CClsub(4) was studied. At low aqueous acidities, HNOsub(3) is extracted by both extractants (S) as HNOsub(3) x S and HNOsub(3)xSsub(2), at > IM HNOsub(3) only HNOsub(3)xS is formed. The distribution of TcOsub(4)sup(-) and Pd(II) is nearly independent of HNOsub(3) concentration. A second power dependence on extractant concentration was found for the extraction of Pd(II) by DBDECMP and TcOsub(4)sup(-) by DBDECP, and a 4th power dependence for TcOsub(4)sup(-) - DBDECMP. (author). 9 refs.; 7 figs.

  2. Separation of 230Th (ionium) from uranium ores sulfuric acid and in nitric acid solutions

    International Nuclear Information System (INIS)

    230Th (ionium) is of interest for production of 231Pa, the Pa isotope with the longest half life, and for production of 232U which can be used in radionuclide batteries. Two procedures are presented which have been worked out for separation of 230Th from sulfuric acid and from nitric acid solutions. In the first case the effluents from the anion exchange resins are the starting material for recorvery of 230Th, in the second case the cation exchange resins which are for purification of U. The procedures selected are simple, economic and can be performed in any uranium mill or uranium purification plant without additional investments. (orig.)

  3. Third phase formation in the extraction of Th(NO3)4 by tri-2-methyl butyl phosphate from nitric acid media

    International Nuclear Information System (INIS)

    Third phase formation in the extraction of Th(IV) by tri-2-methyl butyl phosphate (T2MBP) in various diluents such as n-dodecane, n-tetradecane and n-hexadecane from nitric acid media has been investigated for the first time. The limiting organic concentration (LOC) and maximum organic concentration (MOC) as well as critical aqueous concentration (CAC) and saturated aqueous concentration (SAC) were measured as a function of equilibrium aqueous acidity. Data on LOC and MOC values have been generated with various concentrations of T2MBP (1.1 M, 1.38 M and 1.65 M) in n-dodecane at 303 K. LOC and CAC values have been measured for the extraction of Th(IV) by 1.1 M T2MBP/n-hexadecane at various temperatures (298 K, 303 K and 313 K) as a function of equilibrium aqueous acidity. Effect of temperature on third phase formation has been studied in the extraction of Th(IV) from its solution with near zero free acidity by 1.1 M T2MBP in n-tetradecane and n-hexadecane as diluents. Data on extraction of nitric acid in the absence and presence of Th(IV) by T2MBP/n-dodecane is also reported in this paper. (orig.)

  4. Study of Changes in a Palm-Shell-Based Activated Carbon Characteristics by Nitric Acid

    OpenAIRE

    W.M.A.W. Daud; A.H. Houshmand

    2010-01-01

    A palm-shell-based activated carbon (PSAC) was oxidized with nitric acid solutions at different conditions. A 2-level full factorial design was considered for experimental conditions. Adsorption of nitrogen at 77 K, and Temperature-Programmed Desorption (TPD) were used to study the oxidized PSAC. Although, oxidation by nitric acid decreases the surface area and pore volume of PSAC, however it creates a considerable amount of different oxygen groups on the surface of PSAC.

  5. Chemistry of ruthenium in nitric acid solution with special regard to nuclear fuel solutions

    International Nuclear Information System (INIS)

    A review is given concerning the published knowledge about the chemistry of ruthenium in nitric acid solution with special reference to nitric acid nuclear fuel solutions. Possibilities of the spectroscopic description of the different existing ruthenium complexes are discussed and papers are presented dealing with the estimation of the proportions of the different ruthenium compounds in nuclear fuel solutions. Finally, arguments are derived for the preparation of ruthenium-containing model solutions, which adequately simulate the composition of real nuclear fuel solutions. (author)

  6. A bibliographical review on the radiolysis of uranyl nitrate solutions in nitric acid medium

    International Nuclear Information System (INIS)

    A bibliographical study on the effects of ionizing radiation on uranyl nitrate solutions in nitric acid medium was performed, and the state of knowledge on this subject is presented. The main experimental and theoretical results on water, nitric acid and uranium solutions radiolysis are reviewed and critically evaluated. This paper provides a collection of references as an aid to the development of practical applications, and to stimulate new research on fundamental processes in these systems. (author)

  7. Actinoid sorption from nitric acid onto stainless steel. 1. Plutonium sorption and deposition

    International Nuclear Information System (INIS)

    Data are given on the sorption of plutonium from nitric acid onto 12Kh18N10T stainless steel. This is determined by the contact time, the temperature, the plutonium and nitric acid concentrations, and the element state. The uptake varies in the following sequence: Puh>> Pu(IV) > Pu(VI) > Pu(III). The plutonium deposition on reference specimens has been determined with periodic drying

  8. Solubility of uranyl nitrate in nitric acid solutions of aluminum nitrate

    International Nuclear Information System (INIS)

    The solubility of uranyl nitrate in nitric acid solutions of aluminum nitrate at 250C containing 10, 20 and 30 mass % of nitric acid has been studied by the isothermal method. The Schreinemakers method has been used to establish the composition of the solid phases, which has been confirmed by crystallographic and thermographic studies. Data are presented on the viscosity and density of saturated solutions

  9. Sorption of Pu(IV) on Aliquat-336 impregnated silica-gel from nitric acid - oxalic acid medium

    International Nuclear Information System (INIS)

    A new ion exchange material prepared by impregnating Aliquat-336 on silica-gel has been investigated for the recovery of plutonium from nitric-oxalic acid solutions. The distribution ratio of Pu(IV) was studied at various concentrations of nitric and oxalic acids. The presence of Al(III) and Fe(III) in the solution, enhances the uptake of Pu(IV). Pu(IV) breakthrough capacities (btc) have been determined using 2.5 ml bed of the ion exchange material column in the absence and the presence of Al(III) and Fe(III) nitrate. The elution behavior of Pu(IV) was also studied using nitric acid solutions containing reducing agents. More than 90% of plutonium could be recovered from nitric-oxalic acid solutions. (author)

  10. On the Influence of Nitrates on the Composition of Vapour Phase over Nitric Acid Solutions

    International Nuclear Information System (INIS)

    The paper contains the experimental data for vapour liquid equilibrium and boiling-point temperatures at a pressure of 760 mm Hg, for part of the nitrate - nitric acid - water systems. The authors study systems with nitrates of Al, Fe, Mg, Cu, Na and NH4. They describe in general terms a manner of calculating the evaporation process in waste solutions obtained from the reprocessing of irradiated fuel elements. The high-activity, nitric-acid waste solutions are formed during the extractive reprocessing of irradiated fuel elements. These solutions themselves constitute complex systems, composed of a series of nitrates, in addition to volatile components such as water and nitric acid. Evaporation is usually carried out to reduce the volume of the waste solutions before burial, and in the course of evaporation, nitric acid is driven off. The nitrates in the waste solutions have a definite influence on the distribution of nitric acid between the vapour and liquid phases during evaporation. The work described consists of an attempt to determine this influence for each nitrate, by investigating the vapour/liquid equilibrium in part of the nitrate - nitric acid - water systems. (author)

  11. The Chemistry Study Of Uranium And Transition Elements In Mixture Of Nitric Acid And Sulfuric Acid Were Done

    International Nuclear Information System (INIS)

    The uranium and transition elements were contained in the waste of technetium-99 generator productions to be formed by irradiated uranium. This waste medium is low concentration of nitric acid and sulfuric acid. The tendency of uranium in this medium to form uranyl sulfate complex, the compound of uranyl sulfate belong to heteropoly compounds and is an acid. The transition elements in mixture of nitric acid and sulfuric acid solutions have tendency to form cation complex compound According to difference of the chemical properties of uranium and transition elements, the base reagent can be used for recovery of uranium from this solution

  12. Progress report on nitric-phosphoric acid oxidation

    International Nuclear Information System (INIS)

    The purpose of this program has been to demonstrate a nitric-phosphoric acid destruction technology which can treat a heterogeneous waste stream. This technology is being developed to convert hazardous liquid and solid organics to inorganic gases and salts while simultaneously performing a surface decontamination of the noncombustible items. Pu-238 waste is an issue because it must be shipped to WIPP. However, the presence of organics and Pu-238 waste is an issue because it must be shipped to WIPP. However, the presence of organics and Pu-238 exceeds packaging requirements because of concerns of hydrogen generation. If the TRU can be separated from the organics, the allowable heat load of a container increases a factor of 25. More importantly, since the current shipping package is limited by volume and not heat loading, destroying the organic compounds and decontaminating noncombustible can potentially create a three-order magnitude decrease in the number of shipments that must be made to WIPP. The process envisioned will be configured to handle 1 million pounds (as of 12/91) of a wide range of solid TRU-contaminated waste of which 600,000 pounds is combustible. The process will oxidize the combustibles (a mixture of 14% cellulose, 3% rubber, 64% plastics, 9% absorbed oil, 4% resins and sludges, and 6% miscellaneous organics) without requiring separation from the 400,000 pounds of noncombustibles. The system is being developed to operate below 200 C at moderate pressures (0--15 psig). This report primarily discusses results obtained over the past 3 1/2 months and their impact on the feasibility of a pilot-scale system

  13. Nitric oxide production by visible light irradiation of aqueous solution of nitrosyl ruthenium complexes.

    Science.gov (United States)

    Sauaia, Marília Gama; de Lima, Renata Galvão; Tedesco, Antonio Claudio; da Silva, Roberto Santana

    2005-12-26

    [Ru(II)L(NH(3))(4)(pz)Ru(II)(bpy)(2)(NO)](PF(6))(5) (L is NH(3), py, or 4-acpy) was prepared with good yields in a straightforward way by mixing an equimolar ratio of cis-[Ru(NO(2))(bpy)(2)(NO)](PF(6))(2), sodium azide (NaN(3)), and trans-[RuL(NH(3))(4)(pz)] (PF(6))(2) in acetone. These binuclear compounds display nu(NO) at ca. 1945 cm(-)(1), indicating that the nitrosyl group exhibits a sufficiently high degree of nitrosonium ion (NO(+)). The electronic spectrum of the [Ru(II)L(NH(3))(4)(pz)Ru(II)(bpy)(2)(NO)](5+) complex in aqueous solution displays the bands in the ultraviolet and visible regions typical of intraligand and metal-to-ligand charge transfers, respectively. Cyclic voltammograms of the binuclear complexes in acetonitrile give evidence of three one-electron redox processes consisting of one oxidation due to the Ru(2+/3+) redox couple and two reductions concerning the nitrosyl ligand. Flash photolysis of the [Ru(II)L(NH(3))(4)(pz)Ru(II)(bpy)(2)(NO)](5+) complex is capable of releasing nitric oxide (NO) upon irradiation at 355 and 532 nm. NO production was detected and quantified by an amperometric technique with a selective electrode (NOmeter). The irradiation at 532 nm leads to NO release as a consequence of a photoinduced electron transfer. All species exhibit similar photochemical behavior, a feature that makes their study extremely important for their future application in the upgrade of photodynamic therapy in living organisms. PMID:16363866

  14. Ionisation constants of inorganic acids and bases in aqueous solution

    CERN Document Server

    Perrin, D D

    2013-01-01

    Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution, Second Edition provides a compilation of tables that summarize relevant data recorded in the literature up to the end of 1980 for the ionization constants of inorganic acids and bases in aqueous solution. This book includes references to acidity functions for strong acids and bases, as well as details about the formation of polynuclear species. This text then explains the details of each column of the tables, wherein column 1 gives the name of the substance and the negative logarithm of the ionization constant and column 2

  15. Evaporation and NARS Nitric Acid Mass Balance Summary: 2000--2005

    International Nuclear Information System (INIS)

    A compilation of the historical nitric acid processing data for the evaporation and nitric acid recycle system (NARS) in TA-55 has provided general acid mass balance trends, as well as the location of missing information in both the evaporation system and NARS data logs. The data were accumulated during the calendar years 2000 to 2005. After making a number of processing assumptions, the empirical system information was used to create an interactive spreadsheet that predicts, with moderate accuracy, some of the various stream variables for the combined evaporation and acid recycle processes. Empirical data and interactive calculations were compared to an Aspen Plus(trademark) simulation of the process

  16. Study of free acidity determinations in aqueous solution

    International Nuclear Information System (INIS)

    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)

  17. The resistance of ion exchangers to nitric acid and radiation. Pt. 3

    International Nuclear Information System (INIS)

    The stability to gamma radiation in the dose range from 0.1 to 2 MGy of the Wof MC 50 Chelon exchanger with functional groups of the aminoacetic acid and iminodiacetic acid type has been studied in the air-dry state as well as in the presence of nitric acid. To characterize the radiation-induced reaction it was necessary to determine the capacity of the COOH groups, the nitrogen content, and the amount and composition of radiolysis gas and record the infrared and mass spectra of the irradiated samples. In the case of irradiation in the air-dry state, in water, and in 1 n nitric acid, the main reaction is decarboxylation with G values of 13 +- 2, whereas irradiation in nitric acid in a range of concentration greater than or equal to 7 mol/l results in rapid oxidative breakdown of the functional groups of the resin being superimposed on the radiation-induced reaction. (orig.)

  18. Corrosion properties of high silicon iron-based alloys in nitric acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of copper and rare-earth elements on corrosion behavior of ~iigh silicon iron-based alloys in nitric acid was studied by means of static and loading current corrosion experiments. The anodic polarization curve was also made to discuss the corrosion mechanism. The examination on alloy microstructure and SEM corrosion pattern showed that when silicon content reached 14.5%, the Fe3Si phase appeared and the primary structure of the iron-base alloy was ferrite. When adding 4.57% copper in the iron alloy, its corrosion resistance in static diluted sulfuric acid was improved while its corrosion resistance and electrochemical corrosion properties in the nitric acid were decreased. In contrast, the addition of rare earth elements could improve the corrosion properties in all above conditions including in static diluted sulfuric acid and in nitric acid.

  19. Disposition and transportation of surplus radioactive low specific activity nitric acid. Volume 1, Environmental Assessment

    International Nuclear Information System (INIS)

    DOE is deactivating the PUREX plant at Hanford; this will involve the disposition of about 692,000 liters (183,000 gallons) of surplus nitric acid contaminated with low levels of U and other radionuclides. The nitric acid, designated as low specific activity, is stored in 4 storage tanks at PUREX. Five principal alternatives were evaluated: transfer for reuse (sale to BNF plc), no action, continued storage in Hanford upgraded or new facility, consolidation of DOE surplus acid, and processing the LSA nitric acid as waste. The transfer to BNF plc is the preferred alternative. From the analysis, it is concluded that the proposed disposition and transportation of the acid does not constitute a major federal action significantly affecting the quality of the human environment within the meaning of NEPA; therefore an environmental impact statement is not required

  20. Kinetics of reaction between acetic acid and Ag2+ in nitric acid medium

    International Nuclear Information System (INIS)

    The reaction kinetics between acetic acid and Ag2+ in nitric acid medium is studied by spectrophotometry. The effects of concentrations of acetic acid (HAc), H+, NO3- and temperature on the reaction are investigated. The rate equation has been determined to be -dc(Ag2+)/dt=kc(Ag2+)c(HAc)c-1(H+), where k = (610±15) (mol/L)-1·min-1 with an activation energy of about (48.8±3.5) kJ·mol-1 when the temperature is 25degC and the ionic strength is 4.0 mol/L. The reduction rate of Ag2+ increases with the increase of HAc concentration or temperature and the decrease of HNO3 concentration. However, the effect of NO3- concentrations on the reaction rate is negligible. (author)

  1. The bonding of heavy metals on nitric acid-etched coal fly ashes functionalized with 2-mercaptoethanol or thioglycolic acid

    International Nuclear Information System (INIS)

    Coal fly ash is a waste by-product of the coal fire industry, which generates many environmental problems. Alternative uses of this material would provide efficient solutions for this by-product. In this work, nitric acid-etched coal fly ash labelled with 2-mercaptoethanol or thioglycolic acid was assessed for retention of Al(III), As(III), Cu(II), Cd(II), Fe(III), Mn(II), Hg(II), Ni(II), Pb(II) and Zn(II) ions. The bonding characteristics between the organic compounds with the solid support, as well as with the metal ions, were evaluated using various surface analytical techniques. Visualization of the organically-functionalized coal fly ash particle was possible using scanning electron microscopy (SEM), while the elemental composition of the functionalized material, before and after retention of the metal ions, was obtained by energy dispersive (ED)-X ray spectrometry (XRS) and electrothermal atomic absorption spectrometry (ETAAS). Fourier transform infrared (FT-IR) spectrometry and Raman spectrometry were used to obtain information about the functional groups. It was found that some metal(oid) ions (As, Ni, Pb, Zn) were coordinated through the mercaptan group, while other metal(oid)s (Al, Cd, Cu, Fe, Hg, Mn) were apparently bonded to oxygen atoms. A low-cost and effective solid phase retention system for extraction of heavy metals from aqueous solutions was thus developed. - Graphical abstract: Nitric acid-etched coal fly ash labelled with 2-mercaptoethanol or thioglycolic acid was intended for the retention of heavy metals. The bonding characteristics between the organic compounds with the solid support, as well as with the metal ions, were evaluated using surface analytical techniques. - Highlights: • Coal fly ashes were organically-functionalized. • Organically-functionalized coal fly ashes were spectrometrically characterized. • Organically-functionalized coal fly ashes can be used as an effective solid sorbent for metal(oid)s. • This retention

  2. Spectrofluorimetric determination of nitric oxide at trace levels with 5,6-diamino-1,3-naphthalene disulfonic acid.

    Science.gov (United States)

    Zhang, Xian; Wang, Hong; Liang, Shu-Cai; Zhang, Hua-Shan

    2002-03-01

    Based on the selective reaction that 5,6-diamino-1,3-naphthalene disulfonic acid (DANDS) traps nitric oxide (NO) in the presence of dioxygen to yield the highly fluorescent form, 1-[H]-naphthotriazole-6,8-disulfonic acid in moderately alkaline medium, a new spectrofluorimetric method for the determination of NO has been reported. The method offered the advantage of specificity, sensitivity and a simple protocol for the direct detection of NO in aqueous solution. The linear calibration range for NO was 0.04-1.44 mumoll(-1) with a 3sigma detection limit of 0.6 nmoll(-1). The proposed method has been used to monitor the release of NO from S-nitrosocysteine, a NO-releasing agent. PMID:18968522

  3. Nitric oxide secretion in human conjunctival fibroblasts is inhibited by alpha linolenic acid

    OpenAIRE

    Erdinest, Nir; Shohat, Noam; Moallem, Eli; Yahalom, Claudia; Mechoulam, Hadas; Anteby, Irene; Ovadia, Haim; Solomon, Abraham

    2015-01-01

    Purpose It is known that both human conjunctival fibroblasts (HCF) and corneal epithelial (HCE) cells contribute to the inflammatory process in the ocular surface by releasing inflammatory cytokines. In addition, nitric oxide (NO) has an important role in inflammatory responses in the ocular surface. In the present study, we aimed to characterize the capacity of these cells to release nitric oxide in response to cytokines and Lipopolysaccharide (LPS), and show that Alpha-linoleic acid (ALA) i...

  4. Thermodynamics and kinetics of thermal decomposition of dibutylalkyl and dipentylalkyl phosphonate-nitric acid systems

    International Nuclear Information System (INIS)

    Highlights: • Thermal stability of neat and nitric acid solvated DBalP and DPalP have been studied for the first time. • Incompressible gases and reddish viscous or black solid residues were formed on decomposition. • Decomposition of acid solvated phosphonates was found to be exothermic and follows first order kinetics. • The thermodynamic and kinetic parameters were derived wherever possible. - Abstract: Thermal stability of neat and nitric acid-solvated dibutylalkyl and dipentylalkyl phosphonates was studied under closed air ambience using an adiabatic calorimeter. Enthalpies and kinetic parameters for the decomposition reaction were derived wherever possible and are reported for the first time. The neat compounds were found to be stable up to 555 K while the nitric acid-solvated phosphonates decomposed at lower temperatures (370–403 K) with exothermic rise in temperature and pressure invariably producing incompressible gases. Decomposition of all these acid-solvates followed first order kinetics. The rise in temperature and pressure was found to be strongly dependent on nitric acid content of the acid-solvate. While the neat phosphonates produced solid black residue, the acid-solvates produced a viscous reddish-brown residue on decomposition. Heat capacities (Cp), of acid-solvates (DBPrP·0.6HNO3, DBBP·0.6HNO3 and DBPP·0.6HNO3) were measured at constant pressure using a heat flux type differential scanning calorimeter in the temperature range 305–350 K

  5. Macro level extraction of U(VI) and Pu(IV) by tri-iso-amyl phosphate and tri-n-butyl phosphate from nitric acid media

    International Nuclear Information System (INIS)

    Batch extraction of Pu(IV) by 1.1 M Tri-iso-amyl phosphate (TiAP) in n-dodecane (DD) from plutonium nitrate solutions in nitric acid media has been investigated as a function of metal loading and equilibrium aqueous phase acidity at 303 K under high solvent loading conditions. Co-extraction behavior of U(VI) and Pu(IV) with 1.1 M solutions of trialkyl phosphates (TBP and TiAP) in n-DD from nitric acid media has also been compared by carrying out the extraction from a U-Pu feed solution (21% Pu to mimic PFBR MOX fuel composition) at 303 K. (author)

  6. Mechanism of the extraction of nitric acid and water by organic solutions of tertiary alkyl-amines

    International Nuclear Information System (INIS)

    The micellar aggregation of tri-alkyl-ammonium nitrates in low polarity organic solvents has been verified by viscosity, conductivity and sedimentation velocity measurements. The aggregation depends upon the polarity of solvent, the length of the alkyl radicals and the organic concentration of the various constituents (tri-alkyl-ammonium nitrate, tri-alkyl-amine, nitric acid, water). The amine salification law has been established and the excess nitric acid and water solubilities in the organic solutions have been measured. Nitric acid and water are slightly more soluble in micellar organic solutions than in molecular organic solutions. A description of excess nitric acid containing tri-alkyl-ammonium nitrate solutions is proposed. (author)

  7. Characteristics and mechanism of explosive reactions of Purex solvents with Nitric Acid at elevated temperatures

    International Nuclear Information System (INIS)

    This investigation was undertaken to make clear the energetic properties and mechanism of explosive decomposition of Purex solvent systems (TBP/n-Dodecane/HNO3) by Nitric Acid at elevated temperatures using a calorimetric technique (DSC, ARC) and a chromatographic technique (GC, GC/MS). The measurement of exothermic events of solvent-HNO3 reactions using DSC with a stainless steel sealed cell showed distinct two peaks with maxima at around 170 and 320degC, respectively. The peak at around 170degC was mainly attributed to the reactions of dealkylation products (n-butyl nitrate) of TBP and the solvent with nitric acid, and the peak at around 320degC was attributed to the exothermic decomposition of nitrated dodecanes formed in the foregoing exothermic reaction of dodecane with nitric acid. By using the data obtained in ARC experiments, activation energies of 123.2 and 152.5 kJ/mol were determined for the exothermic reaction of TBP with nitric acid and for the exothermic pyrolysis of n-butyl nitrate, respectively. Some possible pathways were considered for the explosive decomposition of TBP by nitric acid at elevated temperatures. (author)

  8. Effects of Nitric Acid Concentration on the Stability of Alumina Sols

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Alumina sols with a mlar ratio of 1: 50 between aluminum sec- butoxide ( ASB ) and H2 O werefabricated by adding various amounts of nitric acid.The particle shape, zeta potential, polydispersity and effective particle size of alumina sol were examined by a TEM, a zeta PALS granularity analyzer and a zetaPALS zeta potential analyzer, respectively.By analyzing the change of zeta potential and double- layer thickness with nitric acid concentration, the potential energy curves of colloidal particles were mapped on the basis of DLVO theory, and the effects of nitric acid concentration on the stability of alumina sols were intensively studied.The results show that for the alumina sols with a mol ratio of 1: 50 between ASB and H2 O, the total interaction energy of the colloidal particle is at a maximum when the nitric acid concentration is 0.22 mol/ L.Therefore, the stability of the colloid reaches optimum at the nitric acid concentration of 0.22 mol/L.

  9. Decomposition Studies of Triphenylboron, Diphenylborinic Acid and Phenylboric Acid in Aqueous Alkaline Solutions Containing Copper

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, C.L. [Westinghouse Savannah River Company, AIKEN, SC (United States); Peterson, R. A.

    1997-02-11

    This report documents the copper-catalyzed chemical kinetics of triphenylboron, diphenylborinic acid and phenylboric acid (3PB, 2PB and PBA) in aqueous alkaline solution contained in carbon-steel vessels between 40 and 70 degrees C.

  10. Investigation into nitric acid extraction by di-2-ethylhexylphosphoric acid and its acid zirconium (4) and hafnium (4) salts

    International Nuclear Information System (INIS)

    Using IR spectroscopy methods mechanism of nitric acid extraction by solutions of di-2-ethylhexylphosphoric acid HX and its zirconium (4) and hafnium (4) polymeric salts in decane is investigated. Di-2-ethylhexylphosphoric acid extracts HNO3 by usual coordination mechanism adding HNO3 molecules to P=O group of (XH)2 dimer by means of its proton. Zr4 and Hf4 acid salts add HNO3 molecules bidentately due to availability in polymeric molecules of extractant metal atoms - electron acceptors. Structure of separate fragments, being part of polymeric products of adding HNO3 to acid salts and containing nonequivalent POO-groups, is determined. IR spectra absorption band interpretation is carried out

  11. Observation of gaseous nitric acid production at a high-energy proton accelerator facility

    CERN Document Server

    Kanda, Y; Nakajima, H

    2005-01-01

    High-energy protons and neutrons produce a variety of radionuclides as well as noxious and oxidative gases, such as ozone and nitric acid, in the air mainly through the nuclear spallation of atmospheric elements. Samples were collected from the surfaces of magnets, walls, and floors in the neutrino beamline tunnel and the target station of the KEK 12-GeV proton synchrotron facility by wiping surfaces with filter paper. Considerably good correlations were found between the amounts of nitrate and tritium and between those of nitrate and /sup 7/Be. This finding gives evidence that at high-energy proton facilities, nitric acid is produced in the radiolysis of air in beam- loss regions. Also, the nitric acid on the surfaces was found to be desorbed and tended to be more uniform throughout the tunnel due to air circulation. The magnitude of diminishing from the surfaces was in the order of tritium>nitrate>/sup 7/Be1).

  12. Separation of strontium nitrate from nitric-acid extract during production of compound fertilizers

    International Nuclear Information System (INIS)

    The process is studied of isolation of a strontium-containing concentrate formed on decomposition of apatite by nitric acid with previous concentration of the nitric-acid extract by centrifuging or precipitation. The effect of the HNO3 concentration on the degree of isolation of strontium nitrate has been studied. It is shown that the strontium nitrate fraction in the nitric-acid extract in the solid phase is proportional to the HNO3 concentration. When using precipitation, the highest yield of Sr(NO3)2 to the concentrated product was obtained with the use of 54%HNO3. With the centrifuging method, the yield of the strontium nitrate to the concentrated product increases from 54 to 78% with respect to the apatite as the HNO3 concentration increases from 50 to 58%

  13. Observation of gaseous nitric acid production at a high-energy proton accelerator facility

    International Nuclear Information System (INIS)

    High-energy protons and neutrons produce a variety of radionuclides as well as noxious and oxidative gases, such as ozone and nitric acid, in the air mainly through the nuclear spallation of atmospheric elements. Samples were collected from the surfaces of magnets, walls, and floors in the neutrino beamline tunnel and the target station of the KEK 12-GeV proton synchrotron facility by wiping surfaces with filter paper. Considerably good correlations were found between the amounts of nitrate and tritium and between those of nitrate and 7Be. This finding gives evidence that at high-energy proton facilities, nitric acid is produced in the radiolysis of air in beam-loss regions. Also, the nitric acid on the surfaces was found to be desorbed and tended to be more uniform throughout the tunnel due to air circulation. The magnitude of diminishing from the surfaces was in the order of tritium>nitrate>7Be

  14. TESTING OF 304L STAINLESS STEEL IN NITRIC ACID ENVIRONMENTS WITH FLUORIDES AND CHLORIDES

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J.

    2010-10-04

    Impure radioactive material processed in nitric acid solutions resulted in the presence of chlorides in a dissolver fabricated from 304L stainless steel. An experimental program was conducted to study the effects of chloride in nitric acid/fluoride solutions on the corrosion of 304L stainless steel. The test variables included temperature (80, 95, and 110 C) and the concentrations of nitric acid (6, 12, and 14 M), fluoride (0.01, 0.1, and 0.2 M) and chloride (100, 350, 1000, and 2000 ppm). The impact of welding was also investigated. Results showed that the chloride concentration alone was not a dominant variable affecting the corrosion, but rather the interaction of chloride with fluoride significantly affected corrosion.

  15. Method and apparatus for processing ruthenium-containing nitric acid solution by evaporization

    International Nuclear Information System (INIS)

    In evaporization treatment of ruthenium-containing nitric acid in the reprocessing of spent fuels, evaporization of ruthenium is suppressed to improve the decontamination coefficient and corrosion resistance of the constituent materials for the apparatus. In view of the above, ruthenium ions in nitric acid are converted not merely into usual nitrosyl ruthenium complex but into nitrosyl ruthenium complex coordinated with nitro groups before evaporization processing. This can be attained by introducing gaseous nitrogen oxide as small bubbles by way of an introduction tube to a solution of ruthenium-containing nitric acid. Accordingly, when a solution containing nitro complex coordinated with nitro groups is sent into the evaporization tube for evaporation treatment, ruthenium nitrosyl-nitro complex can always be present at a concentration higher than a predetermined level in the evaporization tube to suppress the evaporization of ruthenium. (T.M.)

  16. Third phase formation in nitric acid extraction by n-octyl(phenyl)-n,n-diisobutylcarbamoylmethylphosphine oxide

    International Nuclear Information System (INIS)

    The third phase formation was studied as a function of n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and tri-n-butyl phosphate (TBP) concentrations and temperature in the extraction of nitric acid. The concentration fractions of CMPO and TBP in the second and the third phases were determined by gas chromatography. Both CMPO and TBP were found to be enriched in the third phase. The concentrations of nitric acid in the second and the third phases relatively agreed with the calculated concentrations based on the extraction equilibrium constants of nitric acid by CMPO and TBP. The extraction of Np with the third phase formation was also discussed. 21 refs., 4 figs., 3 tabs

  17. Polymerization of beta-amino acids in aqueous solution

    Science.gov (United States)

    Liu, R.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1998-01-01

    We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged alpha- and beta-amino acids in homogeneous aqueous solution. alpha-Amino acids can be oligomerized efficiently using CDI, but not by EDAC. beta-Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an alpha- and beta-dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.

  18. Acidic aqueous uranium electrodeposition for target fabrication

    International Nuclear Information System (INIS)

    Direct irradiation of targets inside nuclear research or multiple purpose reactors is a common route to produce 99Mo-99mTc radioisotopes. The electroplating of low enriched uranium over nickel substrate might be a potential alternative to produce targets of 235U. The electrochemistry of uranium at low temperature might be beneficial for an alternative route to produce 99Mo irradiation LEU targets. Electrodeposition of uranium can be made using ionic and aqueous solutions producing uranium oxide deposits. The performance of uranium electrodeposition is relatively low because a big competition with H2 evolution happens inside the window of electrochemical reduction potential. This work explores possibilities of electroplating uranium as UO22+ (Uranium-VI) in order to achieve electroplating uranium in a sufficient amount to be commercially irradiated in the future Brazilian RMB reactor. Electroplated nickel substrate was followed by cathodic current electrodeposition from aqueous UO2(NO3)2 solution. EIS tests and modeling showed that a film formed differently in the three tested cathodic potentials. At the lower level, (-1.8V) there was an indication of a double film formation, one overlaying the other with ionic mass diffusion impaired at the interface with nickel substrate as showed by the relatively lower admittance of Warburg component. (author)

  19. Reactivity of tributyl phosphate degradation products with nitric acid: Relevance to the Tomsk-7 accident

    International Nuclear Information System (INIS)

    The reaction of a degraded tributyl phosphate (TBP) solvent with nitric acid is thought to have caused the chemical explosion at the Tomsk-7 reprocessing plant at Tomsk, Russia in 1993. The estimated temperature of the organic layer was not high eneough to cause significant reaction of nitric acid with TBP or hydrocarbon diluent compounds. A more reactive organic compound was likely present in the organic layer that reacted with sufficient heat generation to raise the temperature to the point where an autocatalytic oxidation of the organic solvent was initiated. Two of the most likely reactive compounds that are present in degraded TBP solvents are n-butanol and n-butyl nitrate. The reactions of these compounds with nitric acid are the subject of this study. The objective of laboratory-scale tests was to identify chemical reactions that occur when n-butanol and n-butyl nitrate contact heated nitric acid solutions. Reaction products were identified and quantitified, the temperatures at which these reactions occur and heats of reaction were measured, and reaction variables (temperature, nitric acid concentration, organic concentration, and reaction time) were evaluated. Data showed that n-butyl nitrate is less reactive than n-butanol. An essentially complete oxidation reaction of n-butanol at 110-120 C produced four major reaction products. Mass spectrometry identified the major inorganic oxidation products for both n-butanol and n-butyl nitrate as nitric oxide and carbon dioxide. Calculated heats of reaction for n-butanol and n-butyl nitrate to form propionic acid, a major reaction product, are -1860 cal/g n-butanol and -953 cal/g n-butyl nitrate. These heats of reaction are significant and could have raised the temperature of the organic layer in the Tomsk-7 tank to the point where autocatalytic oxidation of other organic compounds present resulted in an explosion

  20. Studies on reaction runaways for Urex/Purex solvent-nitric acid and red-oil synthesis

    International Nuclear Information System (INIS)

    In PUREX/UREX processes for recycling of spent nuclear fuels, 30% TBP solvent is used, This solvent has a small solubility in the aqueous phase. During concentration of the process solutions by an evaporation route, a runaway reaction between TBP and nitric acid is initiated at above 130 deg. C, leading to rapid pressurization and finally containment failure if proper venting is not provided. Red oil was synthesized for the first time in India, and its physical properties as well as thermodynamic parameters for the reaction were determined. It was experimentally established that the presence of metallic nitrates was not essential for red-oil formation as thought earlier. Various experiments have been completed for single-phase as well as two-phase runs. The most important finding of this work was lowering of the limiting acid concentration from the conventional values. In fact, in these experiments, red oil could be formed even at 2 N aqueous acidity. Thus, safety guidelines based on the classical literature are obsolete. New guidelines for the red-oil-safety are required. (authors)

  1. Oxidation of hydroxylamine by nitrous and nitric acids. Model development from first principle SCRF calculations.

    Science.gov (United States)

    Raman, Sumathy; Ashcraft, Robert W; Vial, Marc; Klasky, Marc L

    2005-09-29

    Ab initio molecular orbital calculations have been performed to develop an elementary reaction mechanism for the autocatalytic and scavenging reactions of hydroxylamine in an aqueous nitric acid medium. An improved understanding of the titled reactions is needed to determine the "stability boundary of hydroxylamine" for safe operations of the plutonium-uranium reduction extraction (PUREX) process. Under the operating conditions of the PUREX process, namely, 6 M nitric acid, the reactive forms of hydroxylamine are NH2OH, NH3OH+, and the complex NH3OH.NO3, and those of nitrous acid are NO+, H2ONO+, N2O4, N2O3, NO2, and NO. High-level CBSQB3/IEFPCM and CBSQB3/COSMO calculations were performed using GAUSSIAN03 to investigate the energy landscape and to explore a large number of possible ion-ion, ion-radical, ion-molecule, radical-radical, radical-molecule, and molecule-molecule pathways available to the reactive forms of the reactants in solution. It was found that in solution the autocatalytic generation of nitrous acid proceeds through free radical pathways at low-hydroxylamine concentrations from unprotonated NH2OH via hydrogen abstraction. At high [NH3OH+], we suggest a possible involvement of the NH3ONO+ intermediate via the reaction NH2ONO + NO2 --> HNO + HONO + NO. The NH3ONO+ intermediate, in turn, is formed favorably via the ion-ion reactions of NH3OH+ with NO+ and/or the reaction between NO+ and hydroxylammonium nitrate (HAN). The intermediates involved in the scavenging reaction of nitrous acid by hydroxylamine are NH3ONO+, NH2ONO, NH2(NO)O, NH(NO)OH, and HONNOH and the rate-determining step is the 1,2-NO migration in NH2ONO leading to NH2(NO)O. Reactions NH2ONO --> NH2(NO)O and NH2(NO)O --> NH(NO)OH were studied with two explicit water molecules and the results are discussed in the context of the importance of the explicit treatment of solvent in the determination of the energetics and mechanism of these processes. The rate constants for the reactions were

  2. Phase equilibrium liquid-vapour in the nitrogen dioxide-nitric acid system

    International Nuclear Information System (INIS)

    Nitrogen dioxide being used as a coolant in some nuclear facilities, its production chemistry and purification techniques are of practical interest. The experimental dependence is obtained of the boiling temperature on the solution composition of nitric acid in nitrogen dioxide and of nitrogen dioxide in nitric acid at the atmospheric pressure by use of Cotrell's ebulliometer. The numerical solution of Gibbs-Duhem's equation in view of solution heats of the components gives the parameters of the phase equilibrium liquid-vapour. The results obtained are tabulated and recommended for designing rectification processes

  3. The dynamics of nitric acid production and the fate of nitrogen oxides

    OpenAIRE

    Russell, Armistead G.; McRae, Gregory J.; Cass, Glen R.

    1985-01-01

    A mathematical model is used to study the fate of nitrogen oxides (NO_x) emissions and the reactions responsible for the formation of nitric acid (HNO_3). Model results indicate that the majority of the NO_x inserted into an air parcel in the Los Angeles basin is removed by dry deposition at the ground during the first 24 h of travel, and that HNO_3 is the largest single contributor to this deposition flux. A significant amount of the nitric acid is produced at night by N_2O_5 hydrolysis. Per...

  4. Thermodynamic and kinetic modelling of the reduction of concentrated nitric acid

    International Nuclear Information System (INIS)

    This research thesis aimed at determining and quantifying the different stages of the reduction mechanism in the case of concentrated nitric acid. After having reported the results of a bibliographical study on the chemical and electrochemical behaviour of concentrated nitric media (generalities, chemical equilibriums, NOx reactivity, electrochemical reduction of nitric acid), the author reports the development and discusses the results of a thermodynamic simulation of a nitric environment at 25 C. This allowed the main species to be identified in the liquid and gaseous phases of nitric acid solutions. The author reports an experimental electrochemical investigation coupled with analytic techniques (infrared and UV-visible spectroscopy) and shows that the reduction process depends on the cathodic overvoltage, and identifies three potential areas. A kinetic modelling of the stationary state and of the impedance is then developed in order to better determine, discuss and quantify the reduction process. The application of this kinetic model to the preliminary results of an electrochemical study performed on 304 L steel is then discussed

  5. Material compatibility evaluation for DWPF nitric-glycolic acid-literature review

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Skidmore, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2013-06-01

    Glycolic acid is being evaluated as an alternative for formic and nitric acid in the DWPF flowsheet. Demonstration testing and modeling for this new flowsheet has shown that glycolic acid and glycolate has a potential to remain in certain streams generated during the production of the nuclear waste glass. A literature review was conducted to assess the impact of glycolic acid on the corrosion of the materials of construction for the DWPF facility as well as facilities downstream which may have residual glycolic acid and glycolates present. The literature data was limited to solutions containing principally glycolic acid.

  6. Stability of ion exchangers against treatment with nitric acid and radiation. Pt. 2

    International Nuclear Information System (INIS)

    The change in the sorption properties of chelating ion exchangers with amino acetic acid and amino diacetic acid groups of the type Wof MC 50, Chelex 100 and Dowex A-1 after treatment with nitric acid is examined. The nitric acid concentration is varied in the range 1-10.5 N; the reaction time varied from 0.5 to 25 h. The reaction temperature was 680C. By destruction of the amino diacetic acid groups the sorption properties are changed. The sorption of cations (Cs+ -0.019 N NH4C1) decreases, goes through a minimum and increases again when the COOH capacity is increased. The sorption of anions (TcO-4 -1 N HNO3) and anionic complexes (PdC142- -1 N HC1) decreases in correlation with the N-content. (orig.)

  7. The stability of ion exchangers towards nitric acid and radiation. 1

    International Nuclear Information System (INIS)

    The behaviour of the chelating ion exchangers Wofatit MC 50, Dowex A 1 and Chelex 100 with aminoacetic acid - and iminodiacetic acid-groups towards nitric in the range of the concentration 1 ... 10.5 mol/l and at temperatures 0C was determined. It is found that the COOH capacity and the N content are rapidly reduced leading to the formation of CO2 and N2. If the exposure to HNO3 continues there is again a rise in the COOH capacity. The i.r.- and mass spectra show that the iminodiacetic acid-groups are destroyed by nitrosative cleavage and CHO groups result, which are then oxidized to COOH groups. The mass spectrum shows that the aminoacetic acid-groups of the resin are nitrosated, which has also been confirmed by the use of nitric acid labelled with 15N. (author)

  8. Disposition of PUREX contaminated nitric acid the role of stakeholder involvement

    International Nuclear Information System (INIS)

    What does the United States space shuttle and the Hanford PUREX facility's contaminated nitric acid have in common. Both are reusable. The PUREX Transition Project has achieved success and, minimized project expenses and waste generation by looking at excess chemicals not as waste but as reusable substitutes for commercially available raw materials. This philosophy has helped PUREX personnel to reuse or recycle more than 2.5 million pounds of excess chemicals, a portion of which is the slightly contaminated nitric acid. After extensive public review, the first shipment of contaminated acid was made in May 1995. Removal of the acid was completed on November 6, 1995 when the fiftieth shipment left the Hanford site. This activity, which avoided dispositioning the contaminated acid as a waste, generated significantly more public input and concern than was expected. One of the lessons learned from this process is to not underestimate public perceptions regarding the reuse of contaminated materials

  9. 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...

  10. Characterisation of chitosan solubilised in aqueous formic and acetic acids

    OpenAIRE

    Esam A. El-Hefian

    2009-01-01

    The intrinsic viscosity of chitosan (MW 7.9 x 105 g mol-1) having a high degree of deacetylation and solubilised in aqueous formic and acetic acids was determined at room temperature. Contact angle and conductivity of the chitosan solutions were also studied. The values of critical coagulation concentration (CCC) were then obtained from the plots of contact angle or conductivity versus concentration.

  11. Investigation of the direct and indirect electrochemical oxidation of hydrazine in nitric acid medium on platinum

    International Nuclear Information System (INIS)

    In nuclear fuel processing by the PUREX process, the purification of plutonium in nitric acid medium requires the oxidation of Pu(III) to Pu(IV), and of hydrazinium nitrate to nitrogen. The study helped to characterize the electrochemical behavior of the oxidation of hydrazinium nitrate and the reduction of nitric acid to nitrous acid, a compound which can chemically oxidize hydrazinium nitrate and Pu(III). Electro-analytical studies on polycrystalline platinum showed that hydrazine is oxidized in two potential zones, which depend on the surface texture of the platinum anode. Electrolysis in separate compartments, carried out in medium-acid media (2 and 4 mo/l) in the potential zone where these processes take place, showed that, at 0.9 V/ECS, the hydrazine oxidation reactions involved are: a four-electron process (75 %) with nitrogen formation and a one-electron process (25 %) with formation of nitrogen and ammonium ion. By contrast, electrolysis carried out at 0.65 V/ECS (with reactivation of the electrode at - 0.2 V/ECS to remove the poison from the platinum) allowed the selective oxidation of hydrazine to nitrogen by the four-electron reaction. Nitric acid can only be reduced to nitrous acid in the absence of hydrazine. For medium-acid media (≤ 6 mol/l), this reaction takes place at potentials below - 0.2 V/ECS. However, the production rate of nitrous acid (partial order 0 with respect to nitric acid) is very low compared with the values obtained for strongly-acid media (6 to 10 mol/l) at the potential of - 0.1 V/ECS. Note that, in concentrated nitric medium, the selectivity of the reduction reaction is 47 to 85 % for nitrous acid, depending on the nitric acid concentration (6 to 10 mol/l) and the potential imposed (- 0.1 ≤ E ≤ 0.6 V/ECS). A kinetic study helped to determine the hydrazine oxidation rates as a function of the operating conditions. In all cases, the reaction rate is of partial order 0 with respect to hydrazine. These studies accordingly

  12. Determination of small amounts of nitric acid in the presence of large amounts of uranium (VI) and extraction of nitric acid into TBP solutions highly loaded with uranyl nitrate

    International Nuclear Information System (INIS)

    A new method for the determination of small amounts of nitric acid in the presence of large amounts of uranium(VI) was elaborated. The method is based on the precipitation of uranium(VI) as iodate and subsequent alkalimetric titration of the acid in the supernatant. The extraction of nitric acid and uranium(VI) with 30% TBP in dodecane was studied at high loading of the organic phase with uranyl nitrate and at 25, 40 and 600C. The results are compared with available published data on the extraction of nitric acid under similar conditions. (orig.)

  13. Intrinsic nitric oxide-stimulatory activity of lipoteichoic acids from different Gram-positive bacteria

    Czech Academy of Sciences Publication Activity Database

    Zídek, Zdeněk; Farghali, H.; Kmoníčková, Eva

    2010-01-01

    Roč. 23, č. 4 (2010), s. 300-310. ISSN 1089-8603 R&D Projects: GA ČR GA305/08/0535 Institutional research plan: CEZ:AV0Z50390512 Keywords : Lipoteichoic acid * Gram-positive bacteria * Nitric oxide Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.384, year: 2010

  14. Dissolution of sludges containing uranium dioxide and metallic uranium in nitric acid

    International Nuclear Information System (INIS)

    The dissolution in nitric acid of sludges containing uranium oxide and uranium has been modeled. That study has shown that it was necessary to continuously feed the dissolver to have an appropriate control of the reaction. If a unique procedure is deemed preferable, NH03 6M has been used

  15. K Basin Sludge Conditioning Testing: Nitric Acid Dissolution Testing of K East Canister Sludge

    International Nuclear Information System (INIS)

    This report describes tests performed by Pacific Northwest National Laboratory (PNNL) for Numatec Hanford Corporation (NHC) as part of the overall activities for the development of the K Basin Sludge Treatment System. These tests were conducted to examine the dissolution behavior of a K East Basin canister sludge composite in nitric acid at the following concentrations: 2 M, 4 M, 6 M, 7.8 M and 10 M and temperatures of 25 C and boiling. Assuming that the sludge was 100% uranium metal, a 4X stoichiometric excess of nitric acid was used for all testing, except that conducted at 4 M. In the 4 M nitric acid dissolution test, 50% excess nitric acid was used resulting in a dissolver solution with a significantly higher solids loading. The boiling tests were conducted for 11 hr, the 25 C dissolution tests were conducted from 24 hr to 2 weeks. For the 25 C dissolution testing, the weight percent residual solids was determined, however, chemical and radiochemical analyses were not performed

  16. Method for the manufacture of nitric acid soluble mixed oxide fuel pellets

    International Nuclear Information System (INIS)

    For the manufacture of nitric acid-soluble mixed oxide fuel pellets with adjustable proportions, the starting powder is ground down to a primary grain size of < 2 μm together with a halogen-free grinding aid and subsequently mixed. The change is then granulated in a rotating chamber, pressed into pellet form and sintered. (orig.)

  17. Susceptibility to stress corrosion cracking of zirconium and titanium alloy in nitric acid

    International Nuclear Information System (INIS)

    The susceptibility to stress corrosion cracking (SCC) of zirconium and titanium alloys used in nuclear fuel reprocessing plants was examined by the slow strain rate tensile test (SSRT) in nitric acid solutions by referencing those results obtained in silicone oil. Titanium alloys like Zr-39%Ti, Zr-15%Ti and Zr-5%Ti, Ti-5%Ta were used. Titanium alloys have not the susceptibility to SCC in nitric acid solutions. On the other hand zirconium have the susceptibility to SCC in the same solutions. In comparison with SSRT results of zirconium specimens with a notch in oil, the reduction ratio of time to failure in nitric acid solutions decreased with increasing temperature. The quasi-cleavage type SCC fracture morphology was observed on the fracture surface of specimens tested in nitric acid. In order to evaluate the effect of crystal anisotropy on SCC, L type specimens and C type specimens, which were machined out parallel and perpendicular to the rolling direction respectively were examined. The susceptibility to SCC of C type notched specimens was higher than that of L type notched specimens, because of the preferential texture of quasi-cleavage planes oriented along the cracking path. (author)

  18. Reaction of formaldehyde and nitric acid in a remotely operated thermosiphon evaporator

    International Nuclear Information System (INIS)

    Conditions have been developed for the safe and successful use of a method for reacting formaldehyde with excess nitric acid, while simulataneously concentrating a fissile uranium nitrate solution. This process, which is being conducted in a remotely operated thermosiphon evaporator, has been adapted to plant scale and is being used to process multikilogram batches

  19. Research on the Reaction Between Technetium and Hydrazine in Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The reaction between technetium and hydrazine in nitric acid medium was studied by the titration ofthe concentration of hydrazine and pursuing the concentration of heptavalent technetium along with time.It is approved that the reaction between technetium and hydrazine includes an inducing period, a fast

  20. Effect of neptunium ions on corrosion of stainless steel in nitric acid solution

    International Nuclear Information System (INIS)

    We have studied corrosion of a stainless steel in nitric acid solution containing neptunium. Using type 304L stainless steel, corrosion tests in boiling neptunium nitrate solution were conducted under immersion and heat-transfer condition. By the weight loss measurement of stainless steel and the quantitative analysis of metallic ions dissolved in solution, the corrosion rates of stainless steel were obtained. The surface morphology was observed by scanning electron microscopy. The corrosion acceleration mechanism was investigated by polarization measurement and spectrophotometry. The corrosion rate of stainless steel was accelerated by addition of neptunium in nitric acid solution. Preferential intergranular corrosion was observed. The corrosion of stainless steel was promoted under heat-transfer condition compared to immersion condition. In polarization measurements, the cathodic over-voltage was decreased; the cathodic current was increased by addition of neptunium. Spectrophotometric measurements showed the oxidization of neptunium in boiling nitric acid. The corrosion mechanism in nitric acid solution containing neptunium suggested the re-oxidation of neptunium. (author)

  1. Brightening of the global cloud field by nitric acid and the associated radiative forcing

    Directory of Open Access Journals (Sweden)

    R. Makkonen

    2012-08-01

    Full Text Available Clouds cool Earth's climate by reflecting 20% of the incoming solar energy, while also trapping part of the outgoing radiation. The effect of human activities on clouds is poorly understood, but the present-day anthropogenic cooling via changes of cloud albedo and lifetime could be of the same order as warming from anthropogenic addition in CO2. Soluble trace gases can increase water condensation to particles, possibly leading to activation of smaller aerosols and more numerous cloud droplets. We have studied the effect of nitric acid on the aerosol indirect effect with the global aerosol-climate model ECHAM5.5-HAM2. Including the nitric acid effect in the model increases cloud droplet number concentrations globally by 7%. The nitric acid contribution to the present-day cloud albedo effect was found to be −0.32 W m−2 and to the total indirect effect −0.46 W m−2. The contribution to the cloud albedo effect is shown to increase to −0.37 W m−2 by the year 2100, if considering only the reductions in available cloud condensation nuclei. Overall, the effect of nitric acid can play a large part in aerosol cooling during the following decades with decreasing SO2 emissions and increasing NOx and greenhouse gases.

  2. [Case of dyspnea due to toilet cleaner containing nitric acid for household use].

    Science.gov (United States)

    Yanagawa, Youichi; Matsukawa, Takehisa; Yokoyama, Kazuhito; Hirano, Yohei; Ri, Tetsunari; Aihara, Koichiro; Iba, Toshiaki; Tanaka, Hiroshi

    2013-09-01

    A 40-year-old male tried to clean a urinal at his home storing 900 mL of a toilet cleaner containing 9.8% nitric acid to remove calcium deposit, and clean the toilet floor for twenty minutes. Immediately after using the cleaner, he experienced eye irritation. He washed out the toilet cleaner. However, he thereafter experienced dyspnea, a compressive sensation in his chest, and chest and back pain about 40 minutes after the cleaning the toilet. He monitored his symptoms overnight and found them to gradually improve. However, the symptoms still remained the next morning and therefore he came to our department on foot. He had no particular past or family history. On arrival, his physiological findings and chest computed tomography scan were negative for any abnormalities. His arterial blood gas analysis revealed a mild abnormality of oxygenation. Observation without any drugs revealed that a complete remission of his symptoms occurred after approximately 4 weeks. Based on the results of the experiments, contact with the mucosal membrane and nitric acid gas produced by any accidentally coexisting metals or contact with moisture, including nitric acid produced by a reaction between CaCO3 and cleaner, may have been the mechanism of occurrence for the symptoms observed in this case. This is the first reported case of nitric acid poisoning due to the use of a toilet cleanser intended for household use. PMID:24224389

  3. Extraction of Palladium from Nitric Acid by Diamides of Di-picolinic Acid

    International Nuclear Information System (INIS)

    The most complicated and urgent problem of atomic industry consists in the safe isolation and storage of radioactive wastes. The long-lived radionuclides presented in high-level liquid wastes (HLLW) pose a potential threat to environment for hundreds and thousands of years. One of the possible ways to reduce the danger of HLLW storages is concerned with treatment of HLLW intended to recovery of long-lived radionuclides and their partitioning into separate fractions. The separation of the most hazardous radionuclides (like transplutonium elements (TPE)) to the individual fraction of low volume leads to decrease of the total volume of HLLW and therefore to decrease of solidified waste storage costs. It should be noted that only in the case of reprocessing it can be possible to recover individual radionuclides (or their fractions) into separate flows with further special approach to each of them. Partitioning of different HLLW is under investigation in many countries now. Numerous processes for recovery of Cs, Sr, TPE and REE have been already developed and tested. At the same time partitioning is only the first step on the road to the following synthesis of materials providing the safe storage of long-lived radionuclides over many thousands of years. The metallic palladium contained in HLLW seems to be a promising material for producing of matrices for incorporation of radioactive wastes. Different methods for palladium recovery have been investigated: reductive precipitation, electrochemical precipitation, sorption and extraction. Of prime importance are extraction methods. Phosphine oxides, carbamoyl-phosphine oxides, crown-ethers, oximes, sulfides and some other compounds were proposed as extractants towards palladium from nitric acid media. It is reasonable to recover palladium into individual fraction during waste partitioning. Diamides of malonic, di-glycolic and pyridine-dicarboxylic (di-picolinic) acids are intensively investigated as extractants for HLLW

  4. Tropospheric nitric acid columns from the IASI satellite instrument interpreted with a chemical transport model: Implications for parameterizations of nitric oxide production by lightning

    Science.gov (United States)

    Cooper, Matthew; Martin, Randall V.; Wespes, Catherine; Coheur, Pierre-Francois; Clerbaux, Cathy; Murray, Lee T.

    2014-08-01

    This paper interprets tropical tropospheric nitric acid columns from the Infrared Atmospheric Sounding Interferometer (IASI) satellite instrument with a global chemical transport model (GEOS-Chem). GEOS-Chem and IASI columns generally agree over the tropical ocean to within 10%. However, the GEOS-Chem simulation underestimates IASI nitric acid over Southeast Asia by a factor of 2. The regional nitric acid bias is confirmed by comparing the GEOS-Chem simulation with additional satellite (High Resolution Dynamics Limb Sounder, Atmospheric Chemistry Experiment Fourier Transform Spectrometer) and aircraft (Pacific Exploratory Mission (PEM)-Tropics A and PEM-West B) observations of the middle and upper troposphere. This bias appears to be driven by the lightning NOx parameterization, both in terms of the magnitude of the NOx source and the ozone production efficiency of concentrated lightning NOx plumes. We tested a subgrid lightning plume parameterization and found that an ozone production efficiency of 15 mol/mol in lightning plumes over Southeast Asia in conjunction with an additional 0.5 Tg N would reduce the regional nitric acid bias from 92% to 6% without perturbing the rest of the tropics. Other sensitivity studies such as modified NOx yield per flash, increased altitude of lightning NOx emissions, decreased convective mass flux, or increased scavenging of nitric acid required unrealistic changes to reduce the bias.

  5. Extraction behavior of molybdenum and zirconium with diisodecylphosphoric acid from nitric acid solution

    International Nuclear Information System (INIS)

    This study was performed mainly from the viewpoint of consumption of diisodecylphosphoric acid (DIDPA) by the extracted Mo and Zr to estimate extraction capacities. The number of DIDPA molecules consumed per one extracted Mo atom was four when the concentration of Mo in the aqueous phase was less than 10-3M and it decreased with increasing Mo concentration. Two molecules of DIDPA were consumed per one extracted Zr atom when the Zr concentration was high. Dependencies of the distribution ratio of Mo on the concentrations of Mo, DIDPA and HNO3 are also described. (author) 15 refs.; 7 figs

  6. Nitric Acid Revamp and Upgrading of the Alarm & Protection Safety System at Petrokemija, Croatia

    Directory of Open Access Journals (Sweden)

    Hoško, I.

    2012-04-01

    Full Text Available Every industrial production, particularly chemical processing, demands special attention in conducting the technological process with regard to the security requirements. For this reason, production processes should be continuously monitored by means of control and alarm safety instrumented systems. In the production of nitric acid at Petrokemija d. d., the original alarm safety system was designed as a combination of an electrical relay safety system and transistorized alarm module system. In order to increase safety requirements and modernize the technological process of nitric acid production, revamping and upgrading of the existing alarm safety system was initiated with a new microprocessor system. The newly derived alarm safety system, Simatic PCS 7, links the function of "classically" distributed control (DCS and logical systems in a common hardware and software platform with integrated engineering tools and operator interface to meet the minimum safety standards with safety integrity level 2 (SIL2 up to level 3 (SIL3, according to IEC 61508 and IEC 61511. This professional paper demonstrates the methodology of upgrading the logic of the alarm safety system in the production of nitric acid in the form of a logical diagram, which was the basis for a further step in its design and construction. Based on the mentioned logical diagram and defined security requirements, the project was implemented in three phases: analysis and testing, installation of the safety equipment and system, and commissioning. Developed also was a verification system of all safety conditions, which could be applied to other facilities for production of nitric acid. With the revamped and upgraded interlock alarm safety system, a new and improved safety boundary in the production of nitric acid was set, which created the foundation for further improvement of the production process in terms of improved analysis.

  7. Gamma-irradiation of malic acid in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-12-01

    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.

  8. Thermodynamics and kinetics of thermal decomposition of diamylamyl phosphonate-nitric acid systems

    International Nuclear Information System (INIS)

    Highlights: ► The thermal hazard characteristics of DAAP has been evaluated for the first time. ► The thermodynamic and kinetic parameters have also been derived wherever possible. ► The onset of decomposition of the acid-solvates depended on the nitric acid content. ► A clear trend was seen in the decomposition of acid-solvates of TBP, TiAP and DAAP. - Abstract: Thermal decomposition of neat diamylamyl phosphonate (DAAP), nitric acid-solvates of DAAP and 1.1 M DAAP/n-dodecane was studied calorimetrically in heat-wait-search mode for the first time. The neat DAAP decomposed beyond 500 K while DAAP·0.7HNO3, DAAP·HNO3 and DAAP·2.1HNO3 decomposed exothermally at 386, 381 and 366 K respectively, indicating the role of amount of nitric acid on decomposition. Mixture of DAAP and 8 M nitric acid decomposed at a lower temperature than the acid solvates with a larger excursion in temperature and pressure yielding hydrocarbons, CO2, CO, NOx and a reddish liquid or a black solid residue. Enthalpy of decomposition of DAAP·0.7HNO3, DAAP·HNO3 and DAAP·2.1HNO3 were found to be −237.7 ± 4.8, −348.9 ± 3.4 and −1002.1 ± 2.6 kJ mol−1 and the activation energy and pre-exponential factors were 127.5 ± 1.5, 121.8 ± 0.8 and 105.3 ± 1.2 kJ mol−1 and 9.0 × 1013, 1.4 × 1012 and 2.2 × 1010 lit mol−1 s 1, respectively. Heat capacity (Cp) of acid solvates were measured and used for deriving the enthalpy change.

  9. Nitric-phosphoric acid oxidation of solid and liquid organic materials

    International Nuclear Information System (INIS)

    Nitric-phosphoric acid oxidation has been developed specifically to address issues that face the Savannah River Site, other defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate SRS solid, Pu-contaminated job-control waste, the technology has also exhibited potential for remediating hazardous and mixed-hazardous waste forms. The process is unique to Savannah River and offers a valuable alternative to other oxidation processes that require extreme temperatures and/or elevated pressures. To address the broad categories of waste, many different organic compounds which represent a cross-section of the waste that must be treated have been successfully oxidized. Materials that have been quantitatively oxidized at atmospheric pressure below 180 degrees C include neoprene, cellulose, EDTA, tributylphosphate, and nitromethane. More stable compounds such as benzoic acid, polyethylene, oils, and resins have been completely decomposed below 200 degrees C and 10 psig. The process uses dilute nitric acid in a concentrated phosphoric acid media as the main oxidant for the organic compounds. Phosphoric acid allow nitric acid to be retained in solution well above its normal boiling point. The reaction forms NOx vapors which can be reoxidized and recycled using air and water. The addition of 0.001M Pd(II) reduces CO generation to near 1% of the released carbon gases. The advantages of this process are that it is straightforward, uses relatively inexpensive reagents, operates at relatively low temperature and pressure, and produces final solutions which are compatible with stainless steel equipment. For organic wastes, all carbon, hydrogen, and nitrogen are converted to gaseous products. If interfaced with an acid recovery system which converts NOx back to nitric acid, the net oxidizer would be oxygen from air

  10. Bile acid induced colonic irritation stimulates intracolonic nitric oxide release in humans.

    OpenAIRE

    F. Casellas; Mourelle, M; Papo, M; Guarner, F; Antolin, M; Armengol, J R; J. R. Malagelada

    1996-01-01

    AIM--To measure the intracolonic release of nitric oxide end products (nitrates plus nitrites) and eicosanoids in response to intraluminal irritation with deoxycholic acid (DCA). PATIENTS--Seven patients with irritable bowel syndrome. METHODS--The left colon was perfused with a solution with or without 3 mM deoxycholic acid. Aspirates were assayed for eicosanoids by specific radioimmuno-assay, and for nitrates plus nitrites by the Griess reaction. To confirm that stimulated colonic mucosa can...

  11. Extraction of uranium(VI) in nitric acid solution with supercritical carbon dioxide fluid containing tributylphosphate

    International Nuclear Information System (INIS)

    Extraction behaviors of U(VI) and selected fission product elements from HNO3 solution into a supercritical CO2 fluid containing tributylphosphate (TBP) were studied under equilibrium and dynamic extraction conditions. Uranium(VI) was found to be extracted in the supercritical CO2 phase as a form of UO2 (NO3)2(TBP)2 with a distribution ratio of, e.g., 2.2±0.3 for the extraction of 2 x 10-4 to 2 x 10-2 M U(VI) from 3 M HNO3 into supercritical CO2-0.3 M TBP mixture at 60 C and 15 MPa. The distribution ratio of U(VI) increased with an increase of HNO3 concentration (0.1-6 M) or TBP (0.1-0.3 M), along with a decrease of pressure (10-40 MPa) at 60 C, and with an increase of the temperature (40-80 C) at 15 MPa. A salting-out effect enhancing the distribution of U(VI) was observed by addition of a fairly high concentration of LiNO3 to the aqueous phase. Results of dynamic extraction using a continuous flow of supercritical CO2-TBP through the aqueous nitric acid solution showed that >98% of U(VI) could be exctracted from 3 M HNO3 + 3 M LiNO3 solution into supercritical CO2-0.08 M TBP (60 C, 15 MPa). Main fission product elements such as lanthanides, Cs, Sr, Ba, Zr, Mo, and Pd were hardly extracted into the supercritical CO2 phase under this condition, which suggests that the supercritical CO2 extraction is a feasible method for the separation and recovery of uranium from these elements. Since rapid and complete removal of the CO2 medium from the extracts is attained by gasification of CO2, the amount of the organic solvent waste generated in the extraction process can be largely minimized. Advantages of the supercritical CO2 extraction in its application to the separation process in the field of nuclear technology are discussed. (orig.)

  12. Corrosion res ance of stainless steels in media of nitric-acid decomposition of apatite

    International Nuclear Information System (INIS)

    Presented are results of investigation of corrosion resistance of stainless steels 06KhN28MDT, 08Kh21N6M2T, 08Kh22N5T and Kh18N10T in media initiating composition of pulp liquid phase of nitric acid decompositon of apatite (phosphoric acid, hydrofluoric acid and fluosilicic acid). Principle application possibility of economically-alloyed as to nickel the 08Kh21N62MT steels for the apparatus equipment of the process instead of highly alloyed 06KhN28MDT steel is established

  13. Solvent extraction of U(VI) and Th(IV) ions with N,N,N‘,N’—tetrabutylsuccinylamide from nitric acid solutions

    Institute of Scientific and Technical Information of China (English)

    王友绍; 孙思修; 等

    1996-01-01

    The solvent extraction of U(VI) and Th(IV) from nitric acid medium by N,N,N',N'-tetrabutylsuccinylamide(TBSA) in a diluent composed of 0.5 volume fraction trimethyl benzene(TMB) and 0.5 volume fraction kerosene(OK) has been studied.The distribution ratios of U(VI) and Th(IV) as a function of aqueous HON3 concentration,extractant concentration and temperature have been measured.From the data,the composition of extracted species,equilibrium constants and enthapies of extraction reaction are also calculated.

  14. Solvent extraction of U(VI) and Th(IV) ions with N,N,N',N'-tetrabutylsuccinylamide from nitric acid solutions

    International Nuclear Information System (INIS)

    The solvent extraction of U(VI) and Th(IV) from nitric acid medium by N,N,N',N'-tetrabutylsuccinylamide (TBSA) in a diluent composed of 0.5 volume fraction trimethyl benzene (TMB) and 0.5 volume fraction kerosene (OK) has been studied. The distribution ratios of U(VI) and Th(IV) as a function of aqueous HNO3 concentration, extractant concentration and temperature have been measured. From the data, the composition of extracted species, equilibrium constants and enthalpies of extraction reaction are also calculated

  15. A process for reductive plutonium stripping from an organic reprocessing solution into an aqueous, nitric solution by use of an electrolytic current

    International Nuclear Information System (INIS)

    A process for reductive plutonium stripping from an organic reprocessing solution into an aqueous, nitric solution by use of an electrolytic current, in which the aqueous solution is free of agents for the stabilization of the reduced valence of the plutonium, a HNO3 concentration in the range of 0.05 to 1.0 mol/l is established in the aqueous solution, and the reduction of Pu(IV) to Pu(III) is carried out at a maximum temperature of 400C. (orig./PW)

  16. Modification of cation-exchange properties of activated carbon by treatment with nitric acid

    International Nuclear Information System (INIS)

    The uptake of inorganic cations by high-surface-area activated carbon can be increased by an order of magnitude by controlled exposure to high concentrations of nitric acid at elevated temperatures. Distribution coefficients of cations are also increased. Oxidation treatment causes some loss in particle strength. Acid strength of the functional groups from the nitric acid treatment is greater than those of the starting material. Surface area measurements from small-angle neutron scattering indicate that the increase in effective ion-exchange capacity is not accompanied by gross changes in the structure of the material. 13C-NMR on solid samples suggests that the concentration of carboxyl and phenolic functional groups in the carbon is increased by the treatment

  17. Improvement in electrochemical capacitance of activated carbon from scrap tires by nitric acid treatment

    Science.gov (United States)

    Han, Yan; Zhao, Ping-Ping; Dong, Xiao-Ting; Zhang, Cui; Liu, Shuang-Xi

    2014-12-01

    Activated carbon (AC) obtained from the industrial pyrolytic tire char is treated by concentrated nitric acid (AC-HNO3) and then used as the electrode material for supercapacitors. Surface properties and electrochemical capacitances of AC and ACHNO3 are studied. It is found that the morphology and the porous texture for AC and AC-HNO3 have little difference, while the oxygen content increases and functional groups change after the acid treatment. Electrochemical results demonstrate that the AC-HNO3 electrode displays higher specific capacitance, better stability and cycling performance, and lower equivalent series resistance, indicating that AC obtained from the industrial pyrolytic tire char treated by concentrated nitric acid is applicable for supercapacitors.

  18. Flotation-nitric acid leach procedure for increasing uranium recovery from a refractory ore

    International Nuclear Information System (INIS)

    The Bureau of Mines investigated a flotation-nitric acid leach procedure as part of the goal to maximize minerals and metals recovered from primary and secondary domestic resources. Studies were conducted on an ore that contained carbon-bearing and sulfide mineralization that rendered a portion of the ore refractory (resistant) to conventional leaching technology. The procedure investigated for treating the ore consisted of the following: (1) separation by flotation of the carbonaceous and sulfidic components from the ore, (2) leaching the flotation concentrate with nitric acid at 1000 to 1100C, (3) leaching the flotation tailings with sulfuric acid, and (4) processing the combined leached slurries in a conventional manner to recover yellow cake. In step 2, HNO3 is converted to gaseous products from which it is regenerated by reacting these products with air and water for further leaching. An overall uranium extraction of 96% was achieved by this procedure

  19. Influence of Oxide Film to Stress Corrosion Cracking of Zirconium in Boiling Nitric Acid Solution

    International Nuclear Information System (INIS)

    Nuclear fuel reprocessing process acts an important role of nuclear energy cycle. In Japan, a commercial reprocessing plant has been operating at the Rokkasho reprocessing plant. Purex process that is used nitric acid and dodecane with tributyl phosphate for solvent has been adopted in the plant. Boiling nitric acid is applied to dissolve oxide spent nuclear fuel. In the boiling nitric acid solution, plant material corrodes severely and intergranular corrosion is observed in stainless steels. In order to avoid corrosion in such severe environment, some equipment in the plants has been made of zirconium, which has excellent corrosion resistance in nitric acid solutions. However, it has been known that zirconium has stress corrosion cracking (SCC) susceptibility in concentrated HNO3 with nobler corrosion potential. Nobler corrosion potential causes breakdowns of passive film having excellent protective performance and raises SCC susceptibility of zirconium in nitric acid solutions. Therefore, it is important to clarify the relationship among potential, growth and the breakdown of oxide film for the SCC initiation mechanism. In this study, we investigated the oxide film growth of zirconium with various potentials in boiling nitric acid solutions. Electrochemical tests and immersion tests with various applied potentials conducted in boiling 3. 6 and 9 mol.dm-3 HNO3. The potentials in the immersion tests were set at 1.3, 1.4 and 1.5 V vs. sat. KCl-Ag/AgCl electrode (SSE). These were in the region of trans-passive state of zirconium in boiling nitric acid solution. The test durations were 10, 100 and 500 h. After the corrosion tests, cross-sectional observations of oxide films were conducted. From the results of anodic polarization curves of zirconium in boiling nitric acid, passivity region was observed through rest potential to about 1.5 V in boiling 6 mol.dm-3 HNO3. Rapid increase of current density was observed at the potential attributed to transition from passivity

  20. The influence of nitric acid on the cloud processing of aerosol particles

    Directory of Open Access Journals (Sweden)

    S. Romakkaniemi

    2006-01-01

    Full Text Available In this paper we present simulations of the effect of nitric acid (HNO3 on cloud processing of aerosol particles. Sulfuric acid (H2SO4 production and incloud coagulation are both affected by condensed nitric acid as nitric acid increases the number of cloud droplets, which will lead to smaller mean size and higher total surface area of droplets. As a result of increased cloud droplet number concentration (CDNC, the incloud coagulation rate is enhanced by a factor of 1–1.3, so that the number of interstitial particles reduces faster. In addition, sulfuric acid production occurs in smaller particles and so the cloud processed aerosol size distribution is dependent on the HNO3 concentration. This affects both radiative properties of aerosol particles and the formation of cloud droplets during a sequence of cloud formation-evaporation events. It is shown that although the condensation of HNO3 increases the number of cloud droplets during the single updraft, it is possible that presence of HNO3 can actually decrease the cloud droplet number concentration after several cloud cycles when also H2SO4 production is taken into account.

  1. Amino Acids Catalyzed Direct Aldol Reactions in Aqueous Micelles

    Institute of Scientific and Technical Information of China (English)

    PENG Yi-Yuan; WANG Qi; DING Qiu-Ping; HE Jia-Qi; CHENG Jin-Pei

    2003-01-01

    @@ Since the discovery of its roles as a good small-organic-molecule catalyst in intramolecular aldol reactions, pro line has drawn considerable attention in synthetic chemistry due to its similarity to the type-Ⅰ aldolases. Recently,List and others have reported some new direct asymmetric intermolecular reactions catalyzed by proline, including aldol, Mannich, Michael, and other analogous reactions. Except for two recent examples, [1,2] proline catalyzed aldol reactions in aqueous micelles have not been reported, nor have other amino acids as organocatalysts in directly catalyzing aldol reaction been reported. Herein we wish to present our recent results regarding environmentally be nign direct aldol reactions catalyzed by amino acids including proline, histidine and arginine in aqueous media.

  2. Ternary mutual diffusion in aqueous (ethambutol dihydrochloride + hydrochloric acid) solutions

    International Nuclear Information System (INIS)

    Highlights: • Ternary diffusion coefficients for aqueous system ethambutol dihydrochloride and hydrochloric acid. • Diffusion of ethambutol dihydrochloride driven by hydrochloric acid gradients. • Coupled diffusion as indicated by cross-diffusion coefficients. - Abstract: Ternary mutual diffusion coefficients measured by the Taylor dispersion method are reported for aqueous solutions of {ethambutol dihydrochloride (1) + HCl (2)} at 25 °C and various carrier solution compositions. Mutual diffusion coefficients estimated from limiting ionic conductivities using Nernst equations are used to discuss the composition dependence of the measured diffusion coefficients. 1H NMR studies, combined with DFT calculations, confirm a fully extended conformation for the diprotonated form of the drug present under these conditions, and are consistent with an electrostatic mechanism for the strongly coupled diffusion of diprotonated ethambutol and HCl

  3. Recovery of nitric acid from simulated acidic high level radioactive waste using pore-filled anion exchange membranes

    International Nuclear Information System (INIS)

    Acidic waste is generated at different stages of nuclear fuel cycle. The waste contains minor amounts of actinides (241Am, Pu, Np) along with large number of long-lived radionuclides such as 137Cs, 90Sr, 106Ru etc. Before disposal or storage, the overall activity of the waste needs to be reduced. Along with this, the high amount of acid present in the waste needs to be removed. In this study, DD has been used to recover nitric acid from acidic solutions with compositions similar to radioactive waste using pore-filled anion exchange membranes

  4. Characterisation of chitosan solubilised in aqueous formic and acetic acids

    Directory of Open Access Journals (Sweden)

    Esam A. El-hefian

    2009-11-01

    Full Text Available The intrinsic viscosity of chitosan (MW 7.9 x 105 g mol-1 having a high degree of deacetylation and solubilised in aqueous formic and acetic acids was determined at room temperature. Contact angle and conductivity of the chitosan solutions were also studied. The values of critical coagulation concentration (CCC were then obtained from the plots of contact angle or conductivity versus concentration.

  5. 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...

  6. Solubility of chlorine in aqueous hydrochloric acid solutions.

    Science.gov (United States)

    Alkan, Mahir; Oktay, Münir; Kocakerim, M Muhtar; Copur, Mehmet

    2005-03-17

    The solubility of chlorine in aqueous hydrochloric acid solutions was studied. The effects of HCl concentration and temperature on the solubility were evaluated, and the thermodynamic parameters of the dissolution were calculated. It was found that the solubility isotherms had a minimum at about 0.5M HCl concentration at all the temperatures studied and that solubility decreased with the increase of temperature at all the HCl concentration range investigated. PMID:15752843

  7. Mediated electrochemical oxidation of organic wastes using a Co (III) mediator in a nitric acid based system

    International Nuclear Information System (INIS)

    An electrochemical cell with a Co(III) mediator and nitric acid electrolyte provides efficient destruction of organic and mixed wastes. The organic waste is concentrated in the anolyte reservoir, where the mediator oxidizes the organics and insoluble transuranic compounds and is regenerated at the anode until the organics are converted to CO2. The nitric acid is an excellent oxidant that facilitates the destruction of the organic components. The anode is not readily attacked by the nitric acid solution, thus the cell can be used for extended continual operation without electrode replacement. 2 figs

  8. Studies on the sorption of Pu(IV) on alumina microspheres from nitric acid - oxalic acid solutions

    International Nuclear Information System (INIS)

    Sorption of Pu(IV) on alumina microspheres prepared by the sol-gel procedure has been investigated for the recovery of plutonium from nitric acid-oxalic acid solutions. Distribution ratio for Pu(IV) between alumina microspheres and nitric acid-oxalic acid have been determined. The influence of the mode of preparation and heat treatment of these microspheres, on the sorption of Pu(IV) have been investigated. Pu(IV) breakthrough capacities have been determined using a 5 ml bed of alumina with solutions of Pu(IV) in 1M HNO3 + 0.05M H2C2O4 and 0.5M HNO3 + 0.05M H2C2O4. The elution behavior of Pu(IV) loaded on these microspheres were studied using nitric acid solutions containing different oxidising and reducing agents. Investigations were also carried out to fix the activity in the alumina matrix by heat treatment. (author)

  9. Solvent extraction of nitric acid, uranium (VI) and thorium (IV) by N, N, N', N'-tetrahexylsuccinylamide

    International Nuclear Information System (INIS)

    A new kind of diamide N,N,N',N'-tetrahexylsuccinylamide (THSA) was synthesized, characterized and used for the extraction of HNO3, U(VI) and Th(IV) in a diluent composed of 0.5 volume fraction 1,2,4-trimethyl benzene (TMB) and 0.5 volume fraction kerosene (OK). Extraction distribution coefficients of U(VI) and Th(IV) as functions of aqueous nitric acid concentration, extractant concentration, temperature and salting-out agent (LiNO3) have been studied, and it is found that THSA as an extractant is superior to TBP for extraction of U(VI) and Th(IV). Back extraction was also studied. At low acidity, the main adduct of THSA and HNO3 is HNO3·THSA. THSA·(HNO3)2 and THSA·(HNO3)3 are also found at high acidity. The compositions of extracted species, apparent equilibrium constants and enthalpies of extraction reactions have also been calculated

  10. Determination of plutonium in nitric acid solution by spectrophotometry of Pu(VI), (2)

    International Nuclear Information System (INIS)

    Effects of co-existing agent and of Pu(IV)-polymer formation on the oxidation of Pu(IV) to Pu(VI) by Ce(IV) has been investigated in connection with the spectrophotometric determination of plutonium in nitric acid solution which includes the measurement of absorbance at 833 nm due to Pu(VI) after oxidizing plutonium ion into Pu(VI). Hydrogen peroxide and nitrite ions were dealt with as interfering species because these are most main radiolysis products in nitric acid solution. If 4 times or more concentration of Ce(IV) than that of hydrogen peroxide or nitrite ion is added to the sample solution, plutonium ion can be converted to Pu(VI) quantitatively even in the presence of these agents. Plutonium(IV) forming its polymer is hard to be oxidized to Pu(VI) by Ce(IV). The oxidation rate of Pu(IV)-polymer increases with the increase of the acid concentration of the solution. It takes, however, more than 1 hour to attain complete oxidation of polymer into Pu(VI) even in 3 M nitric acid solution. (author)

  11. Nitric Acid-Treated Carbon Fibers with Enhanced Hydrophilicity for Candida tropicalis Immobilization in Xylitol Fermentation

    Directory of Open Access Journals (Sweden)

    Le Wang

    2016-03-01

    Full Text Available Nitric acid (HNO3-treated carbon fiber (CF rich in hydrophilic groups was applied as a cell-immobilized carrier for xylitol fermentation. Using scanning electron microscopy, we characterized the morphology of the HNO3-treated CF. Additionally, we evaluated the immobilized efficiency (IE of Candida tropicalis and xylitol fermentation yield by investigating the surface properties of nitric acid treated CF, specifically, the acidic group content, zero charge point, degree of moisture and contact angle. We found that adhesion is the major mechanism for cell immobilization and that it is greatly affected by the hydrophilic–hydrophilic surface properties. In our experiments, we found 3 hto be the optimal time for treating CF with nitric acid, resulting in an improved IE of Candida tropicalis of 0.98 g∙g−1 and the highest xylitol yield and volumetric productivity (70.13% and 1.22 g∙L−1∙h−1, respectively. The HNO3-treated CF represents a promising method for preparing biocompatible biocarriers for multi-batch fermentation.

  12. Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jiao, E-mail: qujiao@bhu.edu.cn [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China); Luo, Chunqiu, E-mail: fplj_lcq@163.com [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Zhang, Qian; Cong, Qiao [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Yuan, Xing [School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China)

    2013-04-01

    Highlights: ► An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ► An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ► This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production.

  13. Fractionation of microimpurities during precipitation of basic zirconium sulfate out of nitric acid solutions

    International Nuclear Information System (INIS)

    A study was made on fractionation of microimpurities during precipitation of basic zirconium sulfate out of concentrated with respect to ZrO2 nitric acid solutions. Investigation into fractionation of Sc(3), Cr(3), Mn(2), Fe(3), Co(2), CU(2), Zn(2) and Y(3) microirpurities during hydrolytic precipitation of basic zirconium sulfate out of nitric acid solutions showed that a majority of microimpurities are characterized by high distribution factors and concentrate in mother liquor. Adsorption isotherms were constructed for Cu(2) and Fe(3) microimpurities. The assumption about the effect of microimpurity nature (ionic charge and radius, the electron structure) on precipitation mechanism was made on the base of obtained data

  14. Evaluation of the Magnesium Hydroxide Treatment Process for Stabilizing PFP Plutonium/Nitric Acid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Mark A.; Schmidt, Andrew J.; Delegard, Calvin H.; Silvers, Kurt L.; Baker, Aaron B.; Gano, Susan R.; Thornton, Brenda M.

    2000-09-28

    This document summarizes an evaluation of the magnesium hydroxide [Mg(OH)2] process to be used at the Hanford Plutonium Finishing Plant (PFP) for stabilizing plutonium/nitric acid solutions to meet the goal of stabilizing the plutonium in an oxide form suitable for storage under DOE-STD-3013-99. During the treatment process, nitric acid solutions bearing plutonium nitrate are neutralized with Mg(OH)2 in an air sparge reactor. The resulting slurry, containing plutonium hydroxide, is filtered and calcined. The process evaluation included a literature review and extensive laboratory- and bench-scale testing. The testing was conducted using cerium as a surrogate for plutonium to identify and quantify the effects of key processing variables on processing time (primarily neutralization and filtration time) and calcined product properties.

  15. Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid

    International Nuclear Information System (INIS)

    Highlights: ► An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ► An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ► This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production

  16. Passive Sampler for Measurements of Atmospheric Nitric Acid Vapor (HNO3 Concentrations

    Directory of Open Access Journals (Sweden)

    Andrzej Bytnerowicz

    2001-01-01

    Full Text Available Nitric acid (HNO3 vapor is an important nitrogenous air pollutant responsible for increasing saturation of forests with nitrogen and direct injury to plants. The USDA Forest Service and University of California researchers have developed a simple and inexpensive passive sampler for monitoring air concentrations of HNO3. Nitric acid is selectively absorbed on 47-mm Nylasorb nylon filters with no interference from particulate NO3-. Concentrations determined with the passive samplers closely corresponded with those measured with the co-located honeycomb annular denuder systems. The PVC protective caps of standardized dimensions protect nylon filters from rain and wind and allow for reliable measurements of ambient HNO3 concentrations. The described samplers have been successfully used in Sequoia National Park, the San Bernardino Mountains, and on Mammoth Mountain in California.

  17. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    Science.gov (United States)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili

    2014-10-01

    In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  18. Effect of carrier concentration on transportation of thorium from nitric acid medium across supported liquid membrane using Aliquat 336 as carrier

    International Nuclear Information System (INIS)

    Thorium transportation across supported liquid membrane from nitric acid as a function of carrier concentration and feed acidity is studied. Thorium transportation increased with nitric acid concentration till 5 M feed acidity and decreased after wards. Thorium permeability coefficient varies greatly as a function of carrier concentration depending on the feed acidity conditions. (author)

  19. Photosynthetic and growth responses of Schima superba seedlings to sulfuric and nitric acid depositions.

    Science.gov (United States)

    Yao, Fang-Fang; Ding, Hui-Ming; Feng, Li-Li; Chen, Jing-Jing; Yang, Song-Yu; Wang, Xi-Hua

    2016-05-01

    A continuing rise in acid deposition can cause forest degradation. In China, acid deposition has converted gradually from sulfuric acid deposition (SAD) to nitric acid deposition (NAD). However, the differing responses of photosynthesis and growth to depositions of sulfuric vs. nitric acid have not been well studied. In this study, 1-year-old seedlings of Schima superba, a dominant species in subtropical forests, were treated with two types of acid deposition SO4 (2-)/NO3 (-) ratios (8:1 and 0.7:1) with two applications (foliar spraying and soil drenching) at two pH levels (pH 3.5 and pH 2.5) over a period of 18 months. The results showed that the intensity, acid deposition type, and spraying method had significant effects on the physiological characteristics and growth performance of seedlings. Acid deposition at pH 2.5 via foliar application reduced photosynthesis and growth of S. superba, especially in the first year. Unlike SAD, NAD with high acidity potentially alleviated the negative effects of acidity on physiological properties and growth, probably due to a fertilization effect that improved foliar nitrogen and chlorophyll contents. Our results suggest that trees were damaged mainly by direct acid stress in the short term, whereas in the long term, soil acidification was also likely to be a major risk to forest ecosystems. Our data suggest that the shift in acid deposition type may complicate the ongoing challenge of anthropogenic acid deposition to ecosystem stability. PMID:26797956

  20. Search for an in-line nitric acid analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Gallagher, K. Y.; Johnson, C. M.

    1980-10-01

    A literature search was conducted to identify possible techniques for measuring mineral acid normality in the presence of heavy metal salts, undissolved solids, and high radiation fields. Of the techniques noted, eight were identified that could be applicable to the objective. The possibilities were reduced to two methods, which warrant further investigation. These two are refractometry and a modified coulometric-polarographic method. All methods are discussed in detail followed by rationale for including or rejecting each for further investigation.

  1. Search for an in-line nitric acid analyzer

    International Nuclear Information System (INIS)

    A literature search was conducted to identify possible techniques for measuring mineral acid normality in the presence of heavy metal salts, undissolved solids, and high radiation fields. Of the techniques noted, eight were identified that could be applicable to the objective. The possibilities were reduced to two methods, which warrant further investigation. These two are refractometry and a modified coulometric-polarographic method. All methods are discussed in detail followed by rationale for including or rejecting each for further investigation

  2. Radiolysis studies of uranyl nitrate solution in nitric acid medium

    International Nuclear Information System (INIS)

    The radiolysis of acidic uranyl nitrate solutions was investigated using Co-60 gamma radiation. Hydrogen peroxide was determined as a function of increasing dose. The UV-vis absorption spectra of the irradiated solutions were measured and the spectral changes were analyzed. The increasing dose increases the absorbance intensities, possibly by an increment in nitrate concentration produced by radiolysis, which can originate the formation of different uranyl complexes in solution. (author)

  3. Study on the Reaction Between Methyl Hydrazine and Formaldehyde in Nitric Acid Medium

    Institute of Scientific and Technical Information of China (English)

    LI; Chuan-bo; CAO; Zhi; BIAN; Xiao-yan; XIAN; Liang; YAN; Tai-hong; ZHENG; Wei-fang

    2012-01-01

    <正>To make sure whether the reaction between formaldehyde and methyl hydrazine (MMH) could happen in dilute nitric acid solution, the condensation reaction between the two ones was investigated at 16 ℃. The reaction was slow and it took over 5 hours to reach the balance and the solution turned yellow at last. The maximum absorption peaks of the product existed at 340 nm and 400-450 nm, respectively.

  4. Pb(II) leaching from waste CRT funnel glass in nitric acid solutions

    OpenAIRE

    A. Strzałkowska; M. Wojtala; J. Siwka

    2012-01-01

    Purpose: The paper presents experimental results of Pb (II) leaching from waste CRT funnel glass using solution of nitric acid (V) . This work focused on examining the impact of concentration and particle size on the leaching percentage of Pb (II) from funnel glass.Design/methodology/approach: Material for the investigation was crushed and sieved. Leaching was carried out using working solutions pfrom co repared ncentrated HNO3 and mechanical stirrer.Findings: The received results show the po...

  5. Comparison of anion exchange resins for recovering plutonium from nitric acid waste

    International Nuclear Information System (INIS)

    Microreticular and macroreticular anion exchange resins were compared for their capability of recovering plutonium from nitric acid waste streams. Plutonium breakthrough capacity and elution behavior of the resins were determined as a function of resin properties. Small-bead microreticular resins with a polystyrene matrix containing 4% divinylbenzene cross-linkage showed the best performance. Of the 20- to 50-mesh resins, the macroreticular resin, Amberlite IRA-938, gave the highest plutonium breakthrough capacity and eluted plutonium the fastest

  6. Nitric Acid Revamp and Upgrading of the Alarm & Protection Safety System at Petrokemija, Croatia

    OpenAIRE

    Hoško, I.; Zečević, N.; Pavlaković, S.

    2012-01-01

    Every industrial production, particularly chemical processing, demands special attention in conducting the technological process with regard to the security requirements. For this reason, production processes should be continuously monitored by means of control and alarm safety instrumented systems. In the production of nitric acid at Petrokemija d. d., the original alarm safety system was designed as a combination of an electrical relay safety system and transistorized alarm module system. I...

  7. Procedure of Destructive Chemical Recovery of Precious Metals in Nitric Acid Production

    OpenAIRE

    Ljubičić, M.; Zečević, N.

    2012-01-01

    The heart of the nitric acid production process is the chemical reactor containing a platinum-based catalyst pack and an associated catchment system, which allows the ammonia oxidation reaction to take place efficiently. Under the severe operating conditions imposed by the high-pressure ammonia oxidation process, the catalyst gauzes experience progressive deterioration, as shown by the restricted surface of the catalyst wires, the loss of catalytic activity and the loss of catalytic materials...

  8. Trans Fatty Acids Induce Vascular Inflammation and Reduce Vascular Nitric Oxide Production in Endothelial Cells

    OpenAIRE

    Iwata, Naomi G.; Pham, Matilda; Rizzo, Norma O.; Cheng, Andrew M.; Maloney, Ezekiel; Kim, Francis

    2011-01-01

    Intake of trans fatty acids (TFA), which are consumed by eating foods made from partially hydrogenated vegetable oils, is associated with a higher risk of cardiovascular disease. This relation can be explained by many factors including TFA's negative effect on endothelial function and reduced nitric oxide (NO) bioavailability. In this study we investigated the effects of three different TFA (2 common isomers of C18 found in partially hydrogenated vegetable oil and a C18 isomer found from rumi...

  9. Autoclave leaching of molybdenite concentrates with catalytic additives of nitric acid

    Science.gov (United States)

    Smirnov, K. M.; Raspopov, N. A.; Shneerson, Ya. M.; Lapin, A. Yu.; Bitkov, G. A.; Men'shikov, Yu. A.; Paskhin, P. N.; Kirichenko, V. P.

    2010-07-01

    The scientific theoretical prerequisites for the use of small additives of nitric acid for the intensification of the autoclave oxidative leaching (AOL) of sulfide concentrates are checked in order to increase the degree of extraction of the base metal with a simultaneous decrease in the cost of the process. The technological parameters of the AOL conditions applied to molybdenite are also refined, and recommendations for a practical application of the apparatus of the process and for a decrease in its cost are made.

  10. Effect of Nitric Acid Concentrations on Synthesis and Stability of Maghemite Nanoparticles Suspension

    OpenAIRE

    Irwan Nurdin; Mohd Rafie Johan; Iskandar Idris Yaacob; Bee Chin Ang

    2014-01-01

    Maghemite (γ-Fe2O3) nanoparticles have been synthesized using a chemical coprecipitation method at different nitric acid concentrations as an oxidizing agent. Characterization of all samples performed by several techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), alternating gradient magnetometry (AGM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta potential. The XRD patterns confirmed that the particles were maghemite. The crysta...

  11. Effects of composite restorations on nitric oxide and uric acid levels in saliva

    OpenAIRE

    Nilgun Akgul; Pinar Gul; Hamit Hakan Alp; Ahmet Kiziltunc

    2015-01-01

    Background and Aims: Dental materials that are used in dentistry should be harmless to oral tissues, and should, therefore, not contain any leachable toxic and diffusible substances capable of causing side effects. This study was intended to investigate the effects on salivary nitric oxide (NO) and uric acid (UA) levels after application of dental composite filling materials to healthy volunteers. Materials and Methods: A total of 52 individuals (32 female and 20 male) participated in the stu...

  12. Heterogeneous formation of polar stratospheric clouds – Part 1: Nucleation of nitric acid trihydrate (NAT)

    OpenAIRE

    C. R. Hoyle; I. Engel; Luo, B. P.; Pitts, M.C.; Poole, L. R.; Grooß, J.-U.; Peter, T

    2013-01-01

    Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoriti...

  13. Heterogeneous formation of polar stratospheric clouds – Part 1: Nucleation of nitric acid trihydrate (NAT)

    OpenAIRE

    C. R. Hoyle; I. Engel; Luo, B. P.; Pitts, M.C.; Poole, L. R.; J.-U. Grooß; Peter, T

    2013-01-01

    Satellite based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For t...

  14. Investigation of scandium nitrate-nitric acid-water-tributylphosphate system. 1. Scandium extraction isotherms

    International Nuclear Information System (INIS)

    Distribution of scandium between 100% tbp and 0.2-1.2 mole/l scandium in the 2.7-12.3 mole/l nitric acid is investigated. It is shown that Sc extracts in undiluted tbp, equilibrium with 6-12 mole/l HNO3, contain approximately from one to five molecules pro atom of scandium in the extracted Sc-complex. 14 refs.; 2 figs

  15. Reactivity of the uranium (U(IV)/U(VI)) and the plutonium (Pu(III)/Pu(IV)) in nitric aqueous solution under ultrasound; De l'influence des ultrasons sur la reactivite de l'uranium (U(IV)/U(VI)) et du plutonium (PU(III)/PU(IV)) en solution aqueuse nitrique

    Energy Technology Data Exchange (ETDEWEB)

    Venault, L

    1998-07-01

    To minimize the volumes of solid waste and industrial effluents generated at the end of cycle, particularly in the spent nuclear fuel reprocessing industry, research is currently under way on so-called innovative processes, designed to induce chemical reactions without adding reagent to the media. Among these processes, the use of ultrasound can prove advantageous, and the purpose of this study is to assess accurately the potential for its application. In the present context, this work shows that the transmission of an ultrasonic wave in aqueous nitric acid solution leads to: the accumulation of nitrous acid in solution, until a steady-sate concentration is reached; the removal of nitrogen monoxide and nitrogen dioxide in the gas stream. The initial kinetics of the formation of HNO{sub 2} in solution was quantified as a function of the nitric acid concentration and the ultrasound intensity. It was also shown than an excess of nitrous acid in nitric solution decomposes under the effect of ultrasound. It is also possible to accumulate hydrogen peroxide in solution during the ultrasonic irradiation of aqueous nitric acid solutions in the presence of a chemical species (N{sub 2}H{sub 5}{sup +}, NH{sub 2}SO{sub 3}H...) which reacts rapidly with HNO{sub 2}, preventing the reduction of H{sub 2}O{sub 2} by HNO{sub 2}. The mechanisms of HNO{sub 2} formation and decomposition, and the mechanism of H{sub 2}O{sub 2} formation during the ultrasonic irradiation of aqueous nitric acid solutions, are presented. Control of H{sub 2}O{sub 2} or HNO{sub 2} in a nitric acid medium under the effect of an ultrasonic wave can be exploited to control redox reactions of uranium and plutonium ions, particularly with respect to the oxidation of U and Pu (U(IV){yields} U(IV) or Pu(III) {yields} Pu(IV)) and the reduction of Pu (Pu(IV){yields} Pu(III). The redox behavior of uranium and plutonium ions in aqueous nitric solution subject to an ultrasonic flux is interpreted in term of effects

  16. Permeation behavior of yttrium from nitric acid medium with DNPPA in hollow fibre membrane module

    International Nuclear Information System (INIS)

    High purity yttrium finds applications in superconductors, phosphors, as additives in alloys, in cancer treatment, etc. Monazite mineral contains ∼ 4% yttrium apart from other rare earths. Its separation from the leach solution obtained from processing monazite is primarily done by solvent extraction using di 2-ethyl hexyl phosphoric acid (D2EHPA) and 2-ethyl hexyl 2-ethyl hexyl phosphonic acid (EHEHPA) as extractants. Recently, use of di nonyl phenyl phosphoric acid (DNPPA) in separating metal ions from highly acidic solution has gained importance due to its low pKa value (2.54). It is worth exploring DNPPA for rare earth separation from acidic solutions. Amongst various separation techniques, hollow fibre membrane offer low capital and operating cost, low energy, solvent inventory and high concentration factors. In the present investigation an attempt has been made to study the permeation behavior of Y (III) from nitric acid medium in a hollow fibre supported liquid membrane (HFSLM) module with DNPPA as carrier

  17. Amide functionalized Calix-Benzocrown-6 ionophore for extraction of cesium from highly concentrated nitric acid medium

    International Nuclear Information System (INIS)

    A series of novel calix(4)arene-benzocrown-6 amide (CBCA) ligands in 1,3-alternate conformations with amidic group attached to aromatic ring of the polyether ring network have been synthesised and evaluated for extraction of caesium from nitric acid medium (1-10M). Isodecyl alcohol (IDA) and o-nitrophenyl hexyl ether (o-NPHE) modified calix/dodecane have been used for extraction studies. The extraction of Cs increases with nitric acid concentration, the maxima is obtained at ∼ 4.5M for calix-benzo-crown-6 (CBC) used as standard, whereas, in case of CBCA this maxima reaches to ∼ 8M nitric acid concentration. This difference is attributed to neutralization of nitric acid by intramolecular buffering effect of amidic group of CBCA. (author)

  18. Kinetics of Reaction Between Tc(Ⅶ) and Monomethylhydrazine or Dimethylhydroxylamine in Nitric Acid Medium Containing Plutonium

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The chemical reaction kinetics research of Tc(Ⅶ) with monomethylhydrazine or dimethylhydroxy-lamine in nitric acid medium demonstrated that Tc(Ⅶ) hardly reacts with the salt-free reagents during the

  19. Application of Primary Abatement Technology for Reduction of N2O Emmision in Petrokemija Nitric Acid Production

    OpenAIRE

    Ćosić, L.; Zečević, N.

    2013-01-01

    Industrial nitric acid production by oxidation of gaseous ammonia with Ostwald procedure produces an unwanted by-product – colorless nitrous oxide, N2O. As emission of N2O represents a very serious problem due of its huge contribution to global warming, certain measures focused on its maximum reduction should be undertaken. Minimization of N2O emission in nitric acid production can be achieved in different parts of the process flow, depe...

  20. Chemical reaction calculation simulation of redox behavior of metal ions and the like in the nitric acid solution

    International Nuclear Information System (INIS)

    It is known that corrosion rate of stainless steel in nitric acid solution is affected by the valence change of oxidizing metallic ions. In this study, we conducted redox reaction analyses using chemical reaction calculation model to clarify the mechanism of valence change. We obtained that the oxidization of metallic ions in the solution is not only caused by nitric acid but also nitrogen oxides. (author)

  1. 4.2. The kinetics of nitric acid decomposition of calcined borosilicate raw material of Ak-Arkhar Deposit

    International Nuclear Information System (INIS)

    Present article is devoted to kinetics of nitric acid decomposition of calcined borosilicate raw material of Ak-Arkhar Deposit. The dependence of nitric acid decomposition of calcined boric raw material for extraction of boron oxide on temperature (20-100 deg C) and process duration (15-60 minutes) was defined. It was defined that at temperature increasing the extraction rate of boron oxide increases from 20.8 to 78.6%.

  2. The solubility of thorium fluoride in nitric acid-hydrofluoric acid solution between 25 and 1000C

    International Nuclear Information System (INIS)

    The solubility of thorium fluoride in 4, 8, and 13 M nitric acid solutions was measured as a function of fluoride concentration at 25, 50 and 1000C. The behavior of the solubility is best explained by the existence in solution of the species ThFsub(n)sup((4-n)+), where n has values between 0 and 4. Equilibrium quotients for the stepwise complexation of thorium by fluoride are calculated. (author)

  3. Novel amino acids: synthesis of furoxan and sydnonimine containing amino acids and peptides as potential nitric oxide releasing motifs.

    Science.gov (United States)

    Nortcliffe, Andrew; Botting, Nigel P; O'Hagan, David

    2013-07-28

    The incorporation of furoxan and sydnonimine ring systems into amino acid side chains is demonstrated with the preparation of four novel amino acids which carry these nitric oxide-releasing motifs. N-((4-Nitrophenoxy)carbonyl)-3-phenylsydnonimine 9 and bis(phenylsulfonyl)furoxan 10 are the key intermediates for introducing the heterocycle side chains onto appropriate amine and alcohol functionalities respectively. Furoxan 5 and 7 both displayed NO release based on determination of nitrite production. Orthogonal amino acid protecting group strategies were deployed to demonstrate that the amino acids could be incorporated into peptide frameworks. By way of demonstration the amino acids were placed centrally into several tripeptide motifs. Griess test assays showed that these amino acids released NO in the presence of γ-glutathione (GST). PMID:23753002

  4. Sulfuric, hydrochloric, and nitric acid-catalyzed triacetone triperoxide (TATP) reaction mixtures: an aging study.

    Science.gov (United States)

    Fitzgerald, Mark; Bilusich, Daniel

    2011-09-01

    The organic peroxide explosive triacetone triperoxide (TATP) is regularly encountered by law enforcement agents in various stages of its production. This study utilizes solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) to examine sulfuric acid-, hydrochloric acid-, and nitric acid-catalyzed TATP syntheses during the initial 24 h of these reactions at low temperatures (5-9°C). Additionally, aging of the reaction mixtures was examined at both low and ambient temperatures (19-21°C) for a further 9 days. For each experiment, TATP could be readily identified in the headspace above the reaction mixture 1 h subsequent to the combination of reagents; at 24 h, TATP and diacetone diperoxide (DADP) were prominent. TATP degraded more rapidly than DADP. Additionally, chlorinated acetones chloroacetone and 1,1,-dichloroacetone were identified in the headspace above the hydrochloric acid-catalyzed TATP reaction mixture. These were not present when the catalyst was sulfuric acid or nitric acid. PMID:21595692

  5. Dissolution of thorium/uranium mixed oxide in nitric acid-hydrofluoric acid solution

    International Nuclear Information System (INIS)

    The dissolution process of thorium oxide and mixed uranium-thorium oxide is studied, as a step of the head-end of the fuel reprocessing. An extensive bibliography was analysed, concerning the main aspects of the system, specially the most important process variables. Proposed mechanisms and models for the thorium oxide dissolution are presented. The laboratory tests were performed in two phases: at first, powdered thoria was used as the material to be dissolved. The objective was to know how changes in he concentrations of the dissolvent solution components HNO3, HF and Al(NO3)3 affect the dissolution rate. The tests were planned according to the fractional factorial method. Thes results showed that it is advantageous to work with powdered material, since the reaction occurs rapidly. And, if the Thorex solution (HNO3 13M, HF 0.05M and Al(NO3)3 0.10M) is a suitable dissolvent, it was verified that it is possible to reduce the concentration of either nitric or fluoridric acid, without reducing the reaction rate to an undesirable value. It was also observed significant interaction between the components of the dissolvent solution. In the second phase of the tests, (Th, 5%U)O2 sintered pellets were used. The main goals were to know the pellets dissolution behaviour and to compare the results for different pellets among themselves. It was observed that the metallurgical history of the material strongly influences its dissolution, specially the density and the microstructure. It was also studied how the (Th,U)O2 mass/Thorex solution volume ratio affects the time needed to obtain an 1 M Th/liter solution. The activation energy for the reaction was obtained. (Author)

  6. Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pitchaiah, K.C.; Sujatha, K.; Rao, C.V.S. Brahmmananda; Subramaniam, S.; Sivaraman, N.; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

    2015-06-01

    In recent years, Supercritical Fluid Extraction (SFE) technique has been widely used for the extraction of metal ions. In the present study, extraction of uranium from nitric acid medium was investigated using supercritical carbon dioxide (Sc-CO{sub 2}) containing various organophosphorous compounds such as trialkyl phosphates e.g. tri-iso-amyl phosphate (TiAP), tri-sec-butyl phosphate (TsBP) and tri-n-butyl phosphate (TBP), dialkylalkyl phosphonates, e.g. diamylamyl phosphonate (DAAP) and dibutyl butyl phosphonate (DBBP), dialkyl hydrogen phosphonates, e.g. dioctyl hydrogen phosphonate (DOHP), dioctylphosphineoxide (DOPO), trioctyl phosphine oxide (TOPO), n-octylphenyl N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) and di-2-ethyl-hexyl phosphoric acid (HDEHP). Some of these ligands have been investigated for the first time in the supercritical phase for the extraction of uranium. The extraction efficiency of uranium was studied with TiAP, DAAP and DBBP as a function of nitric acid concentration; the kinetics of the equilibration period (static extraction) and transportation of the metal complex (dynamic extraction) was investigated. The influence of pressure and temperature on the extraction behaviour of uranium with DAAP was studied from 4 N HNO{sub 3}. The extraction efficiency of uranium from 4 N nitric acid medium was found to increase in the order of phosphates < phosphonates < HDEHP < TOPO < CMPO. In the case of phosphates and phosphonates, the maximum extraction of uranium was found to be from 4 N HNO{sub 3} medium. The acidic extractants, HDEHP and DOHP showed relatively higher extraction at lower acidities. The relative extraction of uranium and thorium from their mixture was also examined using Sc-CO{sub 2} containing phosphates, phosphonates and TOPO. The ligand, TsBP provided better fractionation between uranium and thorium compared to trialkyl phosphates, dialkyl alkyl phosphonates and TOPO.

  7. Supercritical fluid extraction of uranium and thorium from nitric acid medium using organophosphorous compounds

    International Nuclear Information System (INIS)

    In recent years, Supercritical Fluid Extraction (SFE) technique has been widely used for the extraction of metal ions. In the present study, extraction of uranium from nitric acid medium was investigated using supercritical carbon dioxide (Sc-CO2) containing various organophosphorous compounds such as trialkyl phosphates e.g. tri-iso-amyl phosphate (TiAP), tri-sec-butyl phosphate (TsBP) and tri-n-butyl phosphate (TBP), dialkylalkyl phosphonates, e.g. diamylamyl phosphonate (DAAP) and dibutyl butyl phosphonate (DBBP), dialkyl hydrogen phosphonates, e.g. dioctyl hydrogen phosphonate (DOHP), dioctylphosphineoxide (DOPO), trioctyl phosphine oxide (TOPO), n-octylphenyl N,N-diisobutyl carbamoylmethylphosphine oxide (CMPO) and di-2-ethyl-hexyl phosphoric acid (HDEHP). Some of these ligands have been investigated for the first time in the supercritical phase for the extraction of uranium. The extraction efficiency of uranium was studied with TiAP, DAAP and DBBP as a function of nitric acid concentration; the kinetics of the equilibration period (static extraction) and transportation of the metal complex (dynamic extraction) was investigated. The influence of pressure and temperature on the extraction behaviour of uranium with DAAP was studied from 4 N HNO3. The extraction efficiency of uranium from 4 N nitric acid medium was found to increase in the order of phosphates < phosphonates < HDEHP < TOPO < CMPO. In the case of phosphates and phosphonates, the maximum extraction of uranium was found to be from 4 N HNO3 medium. The acidic extractants, HDEHP and DOHP showed relatively higher extraction at lower acidities. The relative extraction of uranium and thorium from their mixture was also examined using Sc-CO2 containing phosphates, phosphonates and TOPO. The ligand, TsBP provided better fractionation between uranium and thorium compared to trialkyl phosphates, dialkyl alkyl phosphonates and TOPO.

  8. Dephosphorization of Steelmaking Slag by Leaching with Acidic Aqueous Solution

    Science.gov (United States)

    Qiao, Yong; Diao, Jiang; Liu, Xuan; Li, Xiaosa; Zhang, Tao; Xie, Bing

    2015-12-01

    In the present paper, dephosphorization of steelmaking slag by leaching with acidic aqueous solution composed of citric acid, sodium hydroxide, hydrochloric acid and ion-exchanged water was investigated. The buffer solution of C6H8O7-NaOH-HCl system prevented changes in the pH values. Kinetic parameters including leaching temperature, slag particle size and pH values of the solution were optimized. The results showed that temperature has no obvious effect on the dissolution ratio of phosphorus. However, it has a significant effect on the dissolution ratio of iron. The dephosphorization rate increases with the decrease of slag particle size and the pH value of the solution. Over 90% of the phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30% below the optimal condition. Leaching kinetics of dephosphorization follow the unreacted shrinking core model with a rate controlled step by the solid diffusion layer, the corresponding apparent activation energy being 1.233 kJ mol-1. A semiempirical kinetic equation was established. After leaching, most of the nC2S-C3P solid solution in the steelmaking slag was selectively dissolved in the aqueous solution and the iron content in the solid residue was correspondingly enriched.

  9. The influence of temperature on REE and TPE sorption by sulfocation exchangers from nitric acid solutions

    International Nuclear Information System (INIS)

    Data of numerical and physical experiments on rare earths sorption from nitric acid solutions on the KU-2 sulfocationite, depending on temperature, are presented. It is shown that capacity in terms of europium at the temperature of 70 deg C for solutions with acidity exceeding 1.0 mol/l and in the range of europium concentrations 0.023-0.0428 mol/l increases by 20-30%. At increased temperature the width of sorptional front increases significantly. The calculated data are isomorphous to sorption process observed in the experiment. 4 refs.; 3 figs.; 2 tabs

  10. Supercritical fluid extraction of uranium from nitric acid employing crown ether

    International Nuclear Information System (INIS)

    Selective extraction and separation of uranium from various matrices is imperative due to its importance as nuclear fuel material. Supercritical fluid extraction of uranium from nitric acid medium employing CO2 as supercritical fluid and di-tert-butyldibenzo-18-crown-6 as co-solvent has been investigated. PFOA was employed as counter ion. Effects of various parameters e.g. pressure, temperature, time of extraction, acidity of medium, metal-to-crown and crown- to-counter ion ratio, on extraction efficiency were examined. Under optimized condition, an extraction efficiency of (58±5)% was obtained. (author)

  11. Electrochemical behaviour of niobium and niobium passive films in nitric acid solutions

    International Nuclear Information System (INIS)

    Electrochemical behaviour of bare niobium and phosphoric acid anodized niobium electrodes is investigated in nitric acid solutions. Electrochemical impedance spectroscopy and polarisation techniques have been used to investigate the open-circuit growth of the passive film. The stability of the anodic oxide film has been studied as a function of the formation voltage, formation current density and concentration of the ambient electrolyte. The results show that the Nb-Nb2O5-1M HNO3 does not behave as a perfect dielectric. The flat band potential and donor concentration of the semiconducting anodic oxide film have been calculated from the Mott-Schottky plots. (author)

  12. 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.

  13. Solvent Extraction of Zr(IV) from Nitric Acid Solutions using CYANEX 272, CYANEX 301 and CYANEX 302

    International Nuclear Information System (INIS)

    The extraction of Zr(IV) from nitric acid solutions using CYANEX 272 (bis(2,4,4-trimethylpentyl) phosphinic acid), bis (2,4,4-trimethylpentyl) dithio phosphinic acid (CYANEX 301) or (bis(2,4,4-trimethylpentyl) mono phosphinic acid (CYANEX 302) in kerosene has been investigated. The various factors affecting the extraction process of Zr(IV) by each of the investigated extractants such as contact time, loading capacity, extractant, metal ion and nitric acid concentration as well as temperature, are separately investigated. The stripping of the extracted zirconium from loaded organic solutions is also carried out using different stripping reagents. The results are compared and the potential advantages of each extractant over the others are exploited in terms of higher loading capacity and selectivity, less nitric acid extraction, equilibration period and reagent concentration

  14. Extraction and stripping behaviour of tri-iso-amyl phosphate and tri-n-butyl phosphate in n-dodecane with U(VI) in nitric acid media

    International Nuclear Information System (INIS)

    Batch extraction of U(VI) by 1.1 M solution of tri-iso-amyl phosphate (TiAP) in n-dodecane (n-DD) from uranyl nitrate solutions in nitric acid media has been investigated as a function of metal loading and equilibrium aqueous phase acidity at 303 K. A method adopted for free acidity determination by using a mixture of potassium oxalate and sodium fluoride for complexing U(VI) has been validated by comparing the data generated in the present study with literature data available for tri-n-butyl phosphate (TBP) under identical conditions. Extraction and stripping behaviour of 1.1 M TiAP/n-DD-U(VI)/HNO3 and 1.1 M TBP/n-DD-U(VI)/HNO3 systems have been compared by carrying out extraction, scrubbing and a series of stripping in cross-current mode. Stripping behaviour of both the solvents loaded with U(VI) and HNO3 has also been investigated as a function of time to understand the effects of nitric acid induced degradation on stripping.

  15. FY13 GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATIONS OF THE DWPF CHEMICAL PROCESS CELL WITH SIMULANTS

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.; Zamecnik, J.; Best, D.

    2014-03-13

    Savannah River Remediation is evaluating changes to its current Defense Waste Processing Facility flowsheet to replace formic acid with glycolic acid in order to improve processing cycle times and decrease by approximately 100x the production of hydrogen, a potentially flammable gas. Higher throughput is needed in the Chemical Processing Cell since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the safety significant gas chromatographs and the potential for production of flammable quantities of hydrogen, eliminating the use of formic acid is highly desirable. Previous testing at the Savannah River National Laboratory has shown that replacing formic acid with glycolic acid allows the reduction and removal of mercury without significant catalytic hydrogen generation. Five back-to-back Sludge Receipt and Adjustment Tank (SRAT) cycles and four back-to-back Slurry Mix Evaporator (SME) cycles were successful in demonstrating the viability of the nitric/glycolic acid flowsheet. The testing was completed in FY13 to determine the impact of process heels (approximately 25% of the material is left behind after transfers). In addition, back-to-back experiments might identify longer-term processing problems. The testing was designed to be prototypic by including sludge simulant, Actinide Removal Product simulant, nitric acid, glycolic acid, and Strip Effluent simulant containing Next Generation Solvent in the SRAT processing and SRAT product simulant, decontamination frit slurry, and process frit slurry in the SME processing. A heel was produced in the first cycle and each subsequent cycle utilized the remaining heel from the previous cycle. Lower SRAT purges were utilized due to the low hydrogen generation. Design basis addition rates and boilup rates were used so the processing time was shorter than current processing rates.

  16. Effect of nitric acid on pretreatment and fermentation for enhancing ethanol production of rice straw.

    Science.gov (United States)

    Kim, Ilgook; Lee, Bomi; Park, Ji-Yeon; Choi, Sun-A; Han, Jong-In

    2014-01-01

    In this study, nitric acid (HNO₃) was evaluated as an acid catalyst for rice straw pretreatment, and, after neutralization, as a sole nitrogen source for subsequent fermentation. Response surface methodology was used to obtain optimal pretreatment condition with respect to HNO₃ concentration (0.2-1.0%), temperature (120-160 °C) and reaction time (1-20 min). In a condition of 0.65% HNO₃, 158.8 °C and 5.86 min, a maximum xylose yield of 86.5% and an enzymatic digestibility of 83.0% were achieved. The sugar solution that contained nitrate derived from the acid catalyst supported the enhancement of ethanol yield by Pichia stipitis from 10.92 g/L to 14.50 g/L. The results clearly reveal that nitric acid could be used not only as a pretreatment catalyst, but also as a nitrogen source in the fermentation process for bioethanol production. It is anticipated that the HNO₃-based pretreatment can reduce financial burden on the cellulosic bioethanol industry by simplifying after-pretreatment-steps as well as providing a nitrogen source. PMID:24274544

  17. Estimation of the Production of Ozone and Nitric Acid in a Proton Accelerator Facility of the Proton Engineering Frontier Project

    International Nuclear Information System (INIS)

    The operation of the high-energy particle accelerator leads to the production of not only radioactive gases, but also radiolytic noxious gases, such as ozone and nitrogen compounds in the air of the facility. Of the radiolytic products, ozone production is usually taken into account for the evaluation of the heath hazard in the operation of the particle accelerator facilities, owing to its high radiolytic yield and much lower maximum acceptable concentration. Nitrogen compounds do not commonly constitute a heath hazard but are of important concern because of its chemical properties of being a strong acid and a strong oxidizing agent. Among the nitrogen compounds, nitric acid is a principal radiolytic compound produced in large quantities and has a potential for the corrosion of the components in the facility. It has founded that at a high-energy proton accelerator facility, nitric acid was produced in the radiolysis of air in beam-loss region. The nitric acid was desorbed on the surface of the magnet, walls, floors and local lead shields. It also tends to be more uniform through the tunnel due to air circulation. In these backgrounds, the production of ozone and nitric acid in proton accelerator facility from Proton Engineering Frontier Project (PEFP) was estimated in this study, because very strong radiation environment leads to an abundant production of nitric acid in such a high-current proton accelerator

  18. Trans fatty acids induce vascular inflammation and reduce vascular nitric oxide production in endothelial cells.

    Directory of Open Access Journals (Sweden)

    Naomi G Iwata

    Full Text Available Intake of trans fatty acids (TFA, which are consumed by eating foods made from partially hydrogenated vegetable oils, is associated with a higher risk of cardiovascular disease. This relation can be explained by many factors including TFA's negative effect on endothelial function and reduced nitric oxide (NO bioavailability. In this study we investigated the effects of three different TFA (2 common isomers of C18 found in partially hydrogenated vegetable oil and a C18 isomer found from ruminant-derived-dairy products and meat on endothelial NF-κB activation and nitric oxide (NO production. Human endothelial cells were treated with increasing concentrations of Elaidic (trans-C18:1 (9 trans, Linoelaidic (trans-C18:2 (9 trans, 12 trans, and Transvaccenic (trans-C18:1 (11 trans for 3 h. Both Elaidic and Linoelaidic acids were associated with increasing NF-κB activation as measured by IL-6 levels and phosphorylation of IκBα, and impairment of endothelial insulin signaling and NO production, whereas Transvaccenic acid was not associated with these responses. We also measured superoxide production, which has been hypothesized to be necessary in fatty acid-dependent activation of NF-κB. Both Elaidic acid and Linoelaidic acid are associated with increased superoxide production, whereas Transvaccenic acid (which did not induce inflammatory responses did not increase superoxide production. We observed differential activation of endothelial superoxide production, NF-κB activation, and reduction in NO production by different C18 isomers suggesting that the location and number of trans double bonds effect endothelial NF-κB activation.

  19. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    Science.gov (United States)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi

    2016-05-01

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO3 + 0.05 M NaF. Complexing the fluoride ions either with Al(NO3)3 or ZrO(NO3)2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO3 + 0.05 M NaF, when complexed with 0.15 M ZrO(NO3)2. XPS analysis confirmed the presence of TiO2 and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance.

  20. The reducibility of sulphuric acid and sulphate in aqueous solution

    International Nuclear Information System (INIS)

    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 100oC. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300oC. 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 50-130oC, 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

  1. Assessing the Parameterization of Nitric Oxide Emissions By Lightning in a Chemical Transport Model with Nitric Acid Columns from the IASI Satellite Instrument

    Science.gov (United States)

    Cooper, M.; Martin, R.; Wespes, C.; Coheur, P. F.; Clerbaux, C.; Murray, L. T.

    2014-12-01

    Nitrogen oxides (NOx ≡ NO + NO2) in the free troposphere largely control the production of ozone (O3), an important greenhouse gas and atmospheric oxidant. As HNO3 is the dominant sink of tropospheric NOx, improved understanding of its production and loss mechanisms can help to better constrain NOx emissions, and in turn improve understanding of ozone production and its effect on climate. However, this understanding is inhibited by the scarcity of direct measurements of free tropospheric HNO3, particularly in the tropics. We interpret tropical tropospheric nitric acid columns from the IASI satellite instrument with a global chemical transport model (GEOS-Chem). Overall GEOS-Chem generally agrees with IASI, however we find that the simulation underestimates IASI nitric acid over Southeast Asia by a factor of two. The bias is confirmed by comparing the GEOS-Chem simulation with additional satellite (HIRDLS, ACE-FTS) and aircraft (PEM-Tropics A and PEM-West B) observations of the middle and upper troposphere. We show that this bias can be explained by the parameterization of lightning NOx emissions, primarily from the misrepresentation of concentrated subgrid lightning NOx plumes. We tested a subgrid lightning plume parameterization and found that an additional 0.5 Tg N with an ozone production efficiency of 15 mol/mol would reduce the regional nitric acid bias from 92% to 6% without perturbing the rest of the tropics. Other sensitivity studies such as modified NOx yield per flash, increased altitude of lightning NOx emissions, or changes to convective mass flux or wet deposition of nitric acid required unrealistic changes to reduce the bias. This work demonstrates the importance of a comprehensive lightning parameterization to constraining NOx emissions.

  2. Extraction and thermodynamic behavior of U(VI) and Th(IV) from nitric acid solution with tri-isoamyl phosphate

    International Nuclear Information System (INIS)

    The extraction behavior of U(VI) and Th(IV) with tri-isoamyl phosphate-kerosene (TiAP-KO) from nitric acid medium was investigated in detail using the batch extraction method as a function of aqueous-phase acidity, TiAP concentration and temperature, then the thermodynamic parameters associated with the extraction were derived by the second-law method. It could be noted that the distribution ratios of U(VI) or Th(IV) increased with increasing HNO3 concentration until 6 or 5 M from 0.1 M. However, a good separation factor (D U(VI)/D Th(IV)) of 88.25 was achieved at 6 M HNO3, and the stripping of U(VI) from TiAP-KO with deionized water or diluted nitric acid was easier than that of Th(IV). The probable extracted species were deduced by log D-log c plot at different temperatures as UO2(NO3)2 x (TiAP)(1-2) and Th(NO3)4 x (TiAP)(2-3), respectively. Additionally, ΔH, ΔG and ΔS for the extraction of U(VI) and Th(IV) revealed that the extraction of U(VI) by TiAP was an exothermic process and was counteracted by entropy change, while the extraction of Th(IV) was an endothermic process and was driven by entropy change. (author)

  3. Temperature and composition effect on the volumic masses of uranium and plutonium nitric acid solutions

    International Nuclear Information System (INIS)

    With an oscillating U-tube densimeter, we measured at different temperatures the volumic masses of uranium, plutonium and nitric acid solutions. By multiple linear regression analysis we found the representative equation of the different parameters in fluence on the volumic mass. We have obtained from the tabulated data the representative equation of the pure water between 15 and 400C with a better precision than 2.10-5g.cm-3. From our own results we have obtained the equations concerning the nitric acid between 0 and 8 M at 200C, then between 15 and 400C. The agreement with our experimental results and with the tabulated data at 200C is in some 10-4g.cm-3 range. At last the general equation which comprises the above found terms is in concordance with the experimental results in +- 1,2.10-3g.cm-3 bracket in the scanned range (200C 0C - 2 M 3] -1 -1 - 1 gl-1 -1). Nevertheless we are not able to explain the difference of 2,3.10-3 g.cm-3 between the constant term of this equation and the choosed origin (the volumic mass of the pure water at 200C). The variations observed between our results and these determined in other laboratories for two constituents systems may be explain by errors in free acidity measurements where these is still no complete agreement between laboratories

  4. Evaluation of various Crown ethers for the supercritical fluid extraction of uranium from nitric acid medium

    International Nuclear Information System (INIS)

    Various crowns have been evaluated for supercritical fluid extraction of uranium from nitric acid medium employing HPFOA as counter ion. Uranium extraction efficiency was found to be influenced by cavity size of crown ether and nature of substituents. Complexation tendency of UO22+ increases with increasing cavity size of crown ether. Electron withdrawing substituents decreased the extraction efficiency which could be attributed to decrease in the basicity of four oxygen atoms and hence their bonding ability. Whereas electron donating substituents increased the efficiency due to increases in basicity of oxygen atoms and hence in increase in bonding ability. (author)

  5. Nitric oxide functions in both methyl jasmonate signaling and abscisic acid signaling in Arabidopsis guard cells

    OpenAIRE

    Saito, Naoki; Nakamura, Yoshimasa; Mori, Izumi C.; Murata, Yoshiyuki

    2009-01-01

    Intracellular components in methyl jasmonate (MeJA) signaling remain largely unknown, to compare those in well-understood abscisic acid (ABA) signaling. We have reported that nitric oxide (NO) is a signaling component in MeJA-induced stomatal closure, as well as ABA-induced stomatal closure in the previous study. To gain further information about the role of NO in the guard cell signaling, NO production was examined in an ABA- and MeJA-insensitive Arabidopsis mutant, rcn1. Neither MeJA nor AB...

  6. Hypergolic Burning of Formylidene and Furfurylidene amines with Red Fuming Nitric Acid as Oxidizer

    Directory of Open Access Journals (Sweden)

    S. P. Panda

    1977-04-01

    Full Text Available Six p-formylidene and six p-furfurylideneamines were synthesized and their ignition delay with red fuming nitric acid (RFNA were measured by cup test method using a high speed camera. Structure - hypergolicity correlation revealed that a p-methyl group inhibits hypergolicity whereas a p-methoxy group accelerates it. Similarly oxidizable non-conjugated benzene rings increase hypergolicity whereas conjugated benzene rings decrease it. On compacting, the p-formylidene anisidine was found to be hypergolic with an ignition delay less than 100 milliseconds.

  7. Direct Synthesis of Phenol from Benzene on an Activated Carbon Catalyst Treated with Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    Cui-hong Chen; Jia-quan Xu; Ming-ming Jin; Gui-ying Li; Chang-wei Hu

    2011-01-01

    Commercially available coal-based activated carbon was treated by nitric acid with different concentrations and the resultant samples were used as catalysts for the direct hydroxylation of benzene to phenol in acetonitrile. Boehm titration, X-ray photoelectron spectroscopy,scanning electron microscope coupled with an energy dispersive X-ray microanalyzer, and Brunauer-Emmett-Teller method were used to characterize toe samples. The number of carboxyl groups on the surface was found to be the main factor affecting the catalytic activity. An optimum catalytic performance with a yield of 15.7% and a selectivity of 87.2% to phenol was obtained.

  8. Rocket Performance of Red Fuming Nitric Acid with Blends of Norbornadiene, Carene and Cardanol

    OpenAIRE

    R. Chhibber; C. Prabhakaran; Kulkarni, S. G.; S.P. Panda

    1992-01-01

    The fuel blends of nornornadiene and carene (50:50 by weight) and norbornadiene, carene and cardanol (40:40:20 by weight) exhibit synergistic hypergolic ignition with red fuming nitric acid (RFNA) as oxidiser. These fuel blends have been evaluated by theoretical calculations of performance parameters and subsequently verified by static firing in a 10 kg/sub f/ thruster at a chamber pressure of around 20 atm, using RFNA (with 21 per cent N/sub 2/O/sub 4/ by weight) as oxidiser. The theo...

  9. Corrosion of high purity Fe-Cr-Ni alloys in 13 N boiling nitric acid

    International Nuclear Information System (INIS)

    Corrosion in boiling nitric acid was investigated for high purity Fe-18%Cr-12%Ni alloys and type 304L stainless steels (SS). Owing to very low impurity concentration, the solution treated high purity alloys show almost no intergranular corrosion while the type 304L SS show severe intergranular corrosion. Both in the high purity alloys and type 304L SS, aging treatments ranging from 873 K to 1073 K for 1 h enhance intergranular corrosion. During the aging treatments, impurities should be segregated to the grain boundaries. The corrosion behaviors were discussed from a standpoint of impurity segregation to grain boundaries. This study is of importance for purex reprocessing of spent fuels

  10. Determination of U(VI) and Pu(IV) in nitric acid solutions with derivative spectroscopy

    International Nuclear Information System (INIS)

    The authors study the absorption spectra and fourth derivative spectra (FDS) of U(VI) and Pu(IV) in nitric acid solutions and the effect of impurities on FDS. The concentrations of U(VI) and Pu(IV) with peak-zero method at 415 nm and peak-area method between 472.5-479.5 nm are determined, respectively. When CHNO3 or CNO3- is in 1.5-3.0 mol/l, U(VI) can be directly determined by FDS, with the analysis deviation -4 mol/l

  11. Study of immiscibilities in the trilaurylamine - dodecane - nitric acid - plutonium system

    International Nuclear Information System (INIS)

    Phase equilibrium in systems made up of trilaurylamine, dodecane, nitric acid tetravalent plutonium is shown by drawing the triangular diagrams. the study of these diagrams provides informations concerning the causes of immiscibility. Heterogeneity of the organic mixtures can be related to some characteristics of the components- dipole moment, molecular polarizability and hydrogen bond exchanging ability-Depending on these, some rules may be established which can be used to make a proper choice of an additive in order to improve the miscibility. As an application a study on the partial substitution of dodecane with decalin, in plutonium extraction experiments, has been done showing a possible improvement of the extraction process. (author)

  12. Supercritical fluid extraction of uranium and thorium from nitric acid solutions with organophosphorus reagents

    International Nuclear Information System (INIS)

    Extraction techniques for the recovery of uranium and transuranic elements from acid waste solutions are important in nuclear waste management. This paper examines the feasibility of extracting uranyl and thorium ions from nitric acid solutions with supercritical CO2 containing the different organophosphorus reagents. In this study, an organophosphorus reagent is dissolved in supercritical CO2 by passing the fluid through a reagent vessel placed upstream of the sample vessel in the extractor. Using TBPO or TOPO in supercritical CO2, effective extraction of uranyl and thorium ions can be achieved even in dilute HNO3 solutions, thus yielding the possibility of reducing acidic waste volumes in nuclear waste treatment. The results may form the basis of a novel extraction process for the treatment of acidified nuclear wastes, while minimizing the production of secondary wastes. 12 refs., 2 figs., 2 tabs

  13. Transport of uranium from nitric acid solution by non-dispersive solvent extraction using a hollow fiber contactor

    International Nuclear Information System (INIS)

    Transport behaviour of uranium from nitric acid medium was investigated using hollow fiber non-dispersive extraction technique. The effect of feed acidity and carrier concentration was studied in counter current mode at a feed flow rate of 3.5 mL/s and an organic phase flow rate of 4.5 mL/s. (author)

  14. Adsorption of itaconic acid from aqueous solutions onto alumina

    Directory of Open Access Journals (Sweden)

    JELENA J. GULICOVSKI

    2008-08-01

    Full Text Available Itaconic acid, IA (C5H6O4, was investigated as a potential flocculant for the aqueous processing of alumina powders. The adsorption of IA, as a function of its concentration and pH value of the solution, onto the alumina surface was studied by the solution depletion method. The stability of the suspensions in the presence of itaconic acid was evaluated in light of the surface charge of the alumina powder used, the degree of dissociation of IA, as well as the sedimentation behavior and rheology of the suspensions. It was found that the adsorption process is extremely pH dependent; the maximum adsorption of IA onto alumina surface occurring at a pH close to the value of the first IA dissociation constant, pKa1. Also, IA does not influence the value of the point of zero charge of alumina. It was shown that IA represents an efficient flocculant for concentrated acidic alumina suspensions.

  15. Anode material selection criteria for selective oxidation of inorganic compounds in nitric acid media

    International Nuclear Information System (INIS)

    Significant progress has been made since the 19606 in developing highly effective anode materials for electrochemical processes, The problem areas currently facing electrochemistry researchers include investigating new composite materials obtained by grafting or doping, improving fabrication techniques to extend the lifetime of the materials while maintaining their selectivity, studying their electrochemical properties and relating them to the material structure. Research on materials with high oxygen over-potentials-materials on which water oxidation is kinetically affected, and which open an electro-activity window on high potentials (2.0 VESH or greater) - has opened new avenues such as the use of various metallic oxide deposits. Two oxide classes were identified from a structural standpoint on the basis of their water oxidation properties: chemisorbed active oxygen anodes (e.g. PtOx, IrO2 or RuO2) and physi-sorbed active oxygen anodes (e.g. SnO2 or PbO2). Selective electrochemical generation of powerful oxidants between 1.4 and 2.0 VESH in concentrated nitric acid media is used in the context of the nuclear fuel cycle, and the potential advantages of new materials with a high oxygen over-potential-other than widely used platinum-have attracted attention. The relevant physical, chemical and electrochemical properties of such materials were therefore investigated to assess their selective oxidation performance. The study focused in particular on identifying the specific aspects of concentrated nitric acid media in the processes occurring at the electrode/solution interface, using linear and cyclic voltammetry, imposed-potential electrolysis and impedance spectroscopy. This approach allowed characterization of the electron charge transfer kinetics of the medium (nitric acid, compared with other acids such as methane sulfonic acid) and of the selected redox couple (Ag(II)/Ag(I) in this case). The tests covered a wide range of materials, including IrO2, SnO2, PbO2

  16. Radiation chemistry of amino acids and peptides in aqueous solutions

    International Nuclear Information System (INIS)

    Radiation chemistry relevant to radiation preservation of high protein foods is reviewed. Some conclusions concerning the chemistry of irradiated amino acids, peptides, and proteins have been derived from product analysis of γ-irradiated solutions while the main mechanistic considerations result from the chemistry and kinetics of free radical intermediates observed by pulse radiolysis. The precursors of chemistry in not too concentrated solutions (-, OH, and H. Their reactivity with molecules and their preference for characteristic groups within the molecule are discussed. The reviewed reactions of the model systems are accountable for a variety of radiolytic products found in irradiated foods. From detailed understanding of radiation chemistry in aqueous and frozen systems formation of many classes of compounds can be predicted or entirely eliminated in order to corroborate and extend the conclusions reached from the animal feeding experiments concerning the formation of toxic, mutagenic, and carcinogenic compounds and/or reduction of the nutritional value of foods

  17. Surface oxide growth on platinum electrode in aqueous trifluoromethanesulfonic acid

    Science.gov (United States)

    Furuya, Yoshihisa; Mashio, Tetsuya; Ohma, Atsushi; Dale, Nilesh; Oshihara, Kenzo; Jerkiewicz, Gregory

    2014-10-01

    Platinum in the form of nanoparticles is the key and most expensive component of polymer electrolyte membrane fuel cells, while trifluoromethanesulfonic acid (CF3SO3H) is the smallest fluorinated sulfonic acid. Nafion, which acts as both electrolyte and separator in fuel cells, contains -CF2SO3H groups. Consequently, research on the electrochemical behaviour of Pt in aqueous CF3SO3H solutions creates important background knowledge that can benefit fuel cell development. In this contribution, Pt electro-oxidation is studied in 0.1 M aqueous CF3SO3H as a function of the polarization potential (Ep, 1.10 ≤ Ep ≤ 1.50 V), polarization time (tp, 100 ≤ tp ≤ 104 s), and temperature (T, 278 ≤ T ≤ 333 K). The critical thicknesses (X1), which determines the applicability of oxide growth theories, is determined and related to the oxide thickness (dox). Because X1 > dox for the entire range of Ep, tp, and T values, the formation of Pt surface oxide follows the interfacial place-exchange or the metal cation escape mechanism. The mechanism of Pt electro-oxidation is revised and expanded by taking into account possible interactions of cations, anions, and water molecules with Pt. A modified kinetic equation for the interfacial place exchange is proposed. The application of the interfacial place-exchange and metal cation escape mechanisms leads to an estimation of the Ptδ+-Oδ- surface dipole (μPtO), and the potential drop (Vox) and electric field (Eox) within the oxide. The Pt-anion interactions affect the oxidation kinetics by indirectly influencing the electric field within the double layer and the surface oxide.

  18. Stainless steels with low contents in residual elements for nitric acid environments. Influence of melting processes

    International Nuclear Information System (INIS)

    Nitric acid solutions, as they are for instance employed in the chemical treatment of nuclear fuels, do not apparently pose any more corrosion problems and the safe use of the several steels is well documented. The most difficult corrosion problems are next those related to ''tunnel'' penetrations, in the hot-rolling direction (longitudinal). This phenomenon can be quite important such as to imperial complex structures. Up to the last few years, the only manner to eliminate such ''tunnel'' corrosions was to carry out special operations of remelting and refining under careful selected slag (Electro Slag Remelting or ESR). It turns out indeed that non metallic inclusions are the prime factors in this type of corrosion. Well adapted ladle refining processes made possible to obtain equivalent results at lower costs, while purity and cleanliness are improved to such a degree that a steel of type Cr 18 - Ni 10 thus produced exhibit a nearly absolute resistance to intergranular corrosion in the 14 N (65%) boiling nitric acid (the Huey test) whatever the ''sensitization'' treatment, between 10000C and 6000C. In view of its very high tolerance to varied thermal cycles and of the near complete disappearance of any ''tunnel'' corrosion, such a steel is of great interest when complex parts are produced, by machining forged or rolled metal, which is then assembled by welding techniques or procedures which would be forbidden in the case of usual Cr 18 -Ni 10 steels. Similar improvements are also obtained on the two other special steels used in nitric environments: Cr 25 - Ni 20 - C <= 0,020 (Nb) and Cr 17 - Ni 14 - Si 4 - C <= 0,015 (Nb)

  19. Procedure of Destructive Chemical Recovery of Precious Metals in Nitric Acid Production

    Directory of Open Access Journals (Sweden)

    Ljubičić, M.

    2012-07-01

    Full Text Available The heart of the nitric acid production process is the chemical reactor containing a platinum-based catalyst pack and an associated catchment system, which allows the ammonia oxidation reaction to take place efficiently. Under the severe operating conditions imposed by the high-pressure ammonia oxidation process, the catalyst gauzes experience progressive deterioration, as shown by the restricted surface of the catalyst wires, the loss of catalytic activity and the loss of catalytic materials. The higher the pressure of gaseous ammonia oxidation, the greater the loss of platinum group metals from the surface of the applied selective heterogeneous catalysts. Total losses for one batch over the whole period of using selective heterogeneous catalysts may account in the range from 20 to 40 % of the total installed quantity of precious metals. An important part of the platinum removed from the platinum-rhodium alloy wires can be recovered at the outlet of the reactor by means of palladium catchment gauzes. However, this catchment process, which is based on the great ability of palladium to alloy with platinum, is not 100 % effective and a fraction of the platinum and practically all of the rhodium lost by the catalyst wires, evades the catchment package and is then deposited in other parts of the plant, especially heat exchangers. From the above mentioned operating equipment, the retained mass of precious metals can be recovered by the technical procedure of non-destructive and destructive chemical solid-liquid extraction.Shown is the technical procedure of destructive chemical recovery of preheater and boiler for preheating and production of steam by applying sulfuric acid (w = 20 % and subsequent procedure of raffination of derived sludge, to the final recovery of precious metals. The technical procedure of destructive chemical recovery of precious metals from preheater and boiler for preheating and production of steam in nitric acid production is

  20. Single-cycle method for partitioning of trivalent actinides using completely incinerable reagents from nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, Jammu; Venkatesan, K.A.; Antony, M.P.; Srinivasan, T.G.; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

    2014-10-01

    A new approach, namely 'Single-cycle method for partitioning of Minor Actinides using completely incinerable ReagenTs' (SMART), has been explored for the separation of Am(III) from Eu(III) present in nitric acid medium. The extraction behavior of Am(III) and Eu(III) in a solution of an unsymmetrical diglycolamide, N,N,-didodecyl-N',N'-dioctyl-3-oxapentane-1,5-diamide (D{sup 3}DODGA), and an acidic extractant, N,N-di-2-ethylhexyl diglycolamic acid (HDEHDGA), in n-dodecane was studied. The distribution ratio of both these metal ions in D{sup 3}DODGA-HDEHDGA/n-dodecane initially decreased with increase in the concentration of nitric acid reached a minimum at 0.1 M nitric acid followed by increase. Synergic extraction of Am(III) and Eu(III) was observed at nitric acid concentrations above 0.1 M and antagonism at lower acidities. Contrasting behavior observed at different acidities was probed by the slope analysis of the extraction data. The study revealed the involvement of both D{sup 3}DODGA and HDEHDGA during synergism and increased participation of HDEHDGA during antagonism. The stripping behavior of Am(III) and Eu(III) from the loaded organic phase was studied as a function of nitric acid, DTPA, and citric acid concentrations. The conditions needed for the mutual separation of Am(III) and Eu(III) from the loaded organic phase were optimized. Our studies revealed the possibility of separating trivalent actinides from HLLW using these completely incinerable reagents. (orig.)

  1. Single-cycle method for partitioning of trivalent actinides using completely incinerable reagents from nitric acid medium

    International Nuclear Information System (INIS)

    A new approach, namely 'Single-cycle method for partitioning of Minor Actinides using completely incinerable ReagenTs' (SMART), has been explored for the separation of Am(III) from Eu(III) present in nitric acid medium. The extraction behavior of Am(III) and Eu(III) in a solution of an unsymmetrical diglycolamide, N,N,-didodecyl-N',N'-dioctyl-3-oxapentane-1,5-diamide (D3DODGA), and an acidic extractant, N,N-di-2-ethylhexyl diglycolamic acid (HDEHDGA), in n-dodecane was studied. The distribution ratio of both these metal ions in D3DODGA-HDEHDGA/n-dodecane initially decreased with increase in the concentration of nitric acid reached a minimum at 0.1 M nitric acid followed by increase. Synergic extraction of Am(III) and Eu(III) was observed at nitric acid concentrations above 0.1 M and antagonism at lower acidities. Contrasting behavior observed at different acidities was probed by the slope analysis of the extraction data. The study revealed the involvement of both D3DODGA and HDEHDGA during synergism and increased participation of HDEHDGA during antagonism. The stripping behavior of Am(III) and Eu(III) from the loaded organic phase was studied as a function of nitric acid, DTPA, and citric acid concentrations. The conditions needed for the mutual separation of Am(III) and Eu(III) from the loaded organic phase were optimized. Our studies revealed the possibility of separating trivalent actinides from HLLW using these completely incinerable reagents. (orig.)

  2. The liquid membrane for extraction of Yttrium and Dysprosium from Acid Nitric

    International Nuclear Information System (INIS)

    The determination of surfactant in liquid membrane has been done. The surfactant is span-80 (sorbitol-monooleate), the liquid membrane phase was the organic phase (O), the internal liquid phase (W) with ratio O/W = 1, and surfactant. The organic phase using D2EHPA in the kerosene and the internal liquid phase using aqua des or acid nitric. The determination of surfactant with variation of span-80 (0,25 - 2%) in the liquid membrane volume. The speed of stirrer was 3500 rpm in 20 minute. The ratio of liquid membrane phase form and external phase (aqua des or acid nitric) was 1, the speed of stirrer was 350 rpm in 10 minute (permeation process). The liquid phase and the liquid membrane phase was separated and then determinated the volume of liquid membrane, the result of percentage of span-80 was 0,25 % volume. The extraction of yttrium and dysprosium in 2 M HNO3 was Kdy = 2.945 and KdDy = 0.019

  3. Separation of Technetium in Nitric Acid Solution With an Extractant Impregnated Resin

    International Nuclear Information System (INIS)

    An extractant impregnated resin (EIR) was prepared by impregnation of Aliquat 336 into Amberlite XAD-4 for separation of technetium from rhodium in nitric acid solution. The prepared EIR showed high preference for rhenium (chemical analogue of technetium) over rhodium. The adsorption isotherms for rhenium were described well by Langmuir equation in both the single and multi-component systems. Maximum adsorption capacities obtained by modelling the isotherms of rhenium were 2.01 meq g-1 and 1.97 meq g-1 for the single and the multi-component systems, respectively. Column tests were also performed to confirm the separation efficiency of rhenium using a jacketed glass column (diam. 11 x L 150). The EIR column showed successful separation of rhenium with the breakthrough volume of about 122 BV for the breakthrough concentration of 0.08. Also the breakthrough data were modelled successfully by assuming a homogeneous diffusion model in the particle phase. The diffusivities obtained from the modelling were in the order of 10-7 cm2 min-1 for a rhenium. The rhenium adsorbed on the bed could be eluted with a high purity by using a nitric acid solution. (authors)

  4. Homogeneous nucleation rates of nitric acid dihydrate (NAD at simulated stratospheric conditions – Part II: Modelling

    Directory of Open Access Journals (Sweden)

    O. Möhler

    2006-01-01

    Full Text Available Activation energies ΔGact for the nucleation of nitric acid dihydrate (NAD in supercooled binary HNO3/H2O solution droplets were calculated from volume-based nucleation rate measurements using the AIDA (Aerosol, Interactions, and Dynamics in the Atmosphere aerosol chamber of Forschungszentrum Karlsruhe. The experimental conditions covered temperatures T between 192 and 197 K, NAD saturation ratios SNAD between 7 and 10, and nitric acid molar fractions of the nucleating sub-micron sized droplets between 0.26 and 0.28. Based on classical nucleation theory, a new parameterisation for ΔGact=A×(T ln SNAD−2+B is fitted to the experimental data with A=2.5×106 kcal K2 mol−1 and B=11.2−0.1(T−192 kcal mol−1. A and B were chosen to also achieve good agreement with literature data of ΔGact. The parameter A implies, for the temperature and composition range of our analysis, a mean interface tension σsl=51 cal mol−1 cm−2 between the growing NAD germ and the supercooled solution. A slight temperature dependence of the diffusion activation energy is represented by the parameter B. Investigations with a detailed microphysical process model showed that literature formulations of volume-based (Salcedo et al., 2001 and surface-based (Tabazadeh et al., 2002 nucleation rates significantly overestimate NAD formation rates when applied to the conditions of our experiments.

  5. U.S. Department of Energy radioactive nitric acid shipping campaign

    International Nuclear Information System (INIS)

    This report is about the disposal of a large quantity of chemicals previously used in the Plutonium/Uranium Extraction Plant (PUREX). Several alternatives were considered for disposal of the over 700,000 liters of this radiologically contaminated nitric acid. These alternatives included sugar denitration, biodenitrification, calcination, chemical conversion to solid sodium nitrate or to ammonium nitrate, or decontamination and re-use. Another alternative was to solicit interest from others that might be able to utilize this material in its current condition. British Nuclear Fuels Inc., located in the United Kingdom, expressed interest in this alternative. DOE Headquarters requested Westinghouse Hanford Company (WHC) Transportation and Packaging group to investigate the feasibility of transferring the radiologically contaminated nitric acid to the United Kingdom. Shipments began in May 1995, and were monitored with DOE's satellite tracking system TRANSCOM. This shipping campaign was successfully completed, with no incidents, and savings realized for cleanup of the PUREX facility in excess of $37 million. This process will be duplicated at the Savannah River Site, with cooperation between SRS and Hanford personnel sharing lessons learned

  6. Nitric acid extraction with monoamide and diamide monitored by second harmonic generation at the water/dodecane interface

    International Nuclear Information System (INIS)

    The interfacial properties of the DEHiBA and DMDBTDMA extractant molecules used in the nuclear industry are examined to obtain a better understanding of ion transfer across the water/oil interface. Optical second harmonic generation (SHG) is used in combination with bulk nitric acid titration and interfacial tension (IFT) measurements. First, the amphiphilic properties of both extractant molecules are characterized by static IFT. Second, real time SHG experiments and titration are carried out to follow the kinetics of nitric acid extraction. The SHG intensity evolution is strongly dependant on the extractant concentration in the organic phase and the SHG intensity fluctuations are correlated with the nitric acid flux across the interface. It suggests that these intensity fluctuations are the signature of a strong modification of extractant concentration at the interface that is maximal close to a critical aggregation concentration of extractant in the organic phase. (authors)

  7. Oxidation-reduction reactions of simple hydroxamic acids and plutonium(IV) ions in nitric acid

    OpenAIRE

    Carrott, M. J.; Fox, O. D.; LeGurun, G.; Jones, C J; Mason, C; Taylor, Robin; Andrieux, Fabrice; Boxall, Colin

    2008-01-01

    Simple hydroxamic acids such as formo- and aceto-hydroxamic acids have been proposed as suitable reagents for the separation of either Pu and/or Np from U in modified or single cycle Purex based solvent extraction processes designed to meet the emerging requirements of advanced fuel cycles. The stability of these hydroxamic acids is dominated by their decomposition through acid hydrolysis. Kinetic studies of the acid hydrolysis of formo- and acetohydroxamic acids are reported in the absence a...

  8. Microwave-assisted digestion procedures for biological samples with diluted nitric acid: identification of reaction products.

    Science.gov (United States)

    Gonzalez, Mário H; Souza, Gilberto B; Oliveira, Regina V; Forato, Lucimara A; Nóbrega, Joaquim A; Nogueira, Ana Rita A

    2009-07-15

    Microwave-assisted sample preparation using diluted nitric acid solutions is an alternative procedure for digesting organic samples. The efficiency of this procedure depends on the chemical properties of the samples and in this work it was evaluated by the determination of crude protein amount, fat and original carbon. Soybeans grains, bovine blood, bovine muscle and bovine viscera were digested in a cavity-microwave oven using oxidant mixtures in different acid concentrations. The digestion efficiency was evaluated based on the determination of residual carbon content and element recoveries using inductively coupled plasma optical emission spectrometry (ICP OES). In order to determine the main residual organic compounds, the digests were characterized by nuclear magnetic resonance ((1)H NMR). Subsequently, studies concerning separation of nitrobenzoic acid isomers were performed by ion pair reversed phase liquid chromatography using a C18 stationary phase, water:acetonitrile:methanol (75:20:5, v/v/v)+0.05% (v/v) TFA as mobile phase and ultraviolet detection at 254 nm. Sample preparation based on diluted acids proved to be feasible and a recommendable alternative for organic sample digestion, reducing both the reagent volumes and the variability of the residues as a result of the process of decomposition. It was shown that biological matrices containing amino acids, proteins and lipids in their composition produced nitrobenzoic acid isomers and other organic compounds after cleavage of chemical bonds. PMID:19559896

  9. Thermodynamics of uranium extraction from nitric acid solution by TBP loaded on inert supporting material

    International Nuclear Information System (INIS)

    Thermodynamic investigation of the extraction of both uranium(VI) and uranium(IV) from nitric acid solutions using tri-n-butyl phosphate (TBP) loaded on polyacrylic acid polymer (SM-7) as an inert supporting material has been done using batch technique. The effect of temperature on the equilibrium extraction values has been utilized to evaluate the change in standard thermodynamic quantities (viz. ΔH, ΔS, and ΔG). The Freundlich isotherm was successfully applied to the extraction data of both metal ions. The Dubinin-Radushkevich (D-R) isotherm was found to be valid only in case of U(IV) extraction. Based on the D-R expression, the maximum extraction capacity of loaded TBP and the mean free energy of U(IV) extraction have been determined. (author)

  10. Investigation of uranium sorption from nitric acid solutions by different ion exchange materials

    International Nuclear Information System (INIS)

    One acquired data on U sorption from the reference nitric acid solutions based on the ion-exchange resins varying in the rank. The KRF-20 phosphoric acid cationite, the ampholyte with the iminodiphosphonic groups (S-950) and the cationite with the mixed phosphonic and sulfogroups (S-957) were shown to manifest the best sorption characteristics as to U. One determined the dependences of the static exchange capacity of the above-mentioned resins on HNO3 concentration, the values of the capacity prior to breakthrough (CPB) as to U, as well as the U sorption isotherms at HNO3 concentration equal to 1 and 3 mole/l. One showed the possibility of the desorption of the absorbed U by Na2CO3 hot solutions

  11. Electrochemical oxidation of 243Am(III) in nitric acid by a terpyridyl-derivatized electrode

    Energy Technology Data Exchange (ETDEWEB)

    Dares, C. J.; Lapides, A. M.; Mincher, B. J.; Meyer, T. J.

    2015-11-05

    A high surface area, tin-doped indium oxide electrode surface-derivatized with a terpyridine ligand has been applied to the oxidation of trivalent americium to Am(V) and Am(VI) in nitric acid. Potentials as low as 1.8 V vs. the saturated calomel electrode are used, 0.7 V lower than the 2.6 V potential for one-electron oxidation of Am(III) to Am(IV) in 1 M acid. This simple electrochemical procedure provides, for the first time, a method for accessing the higher oxidation states of Am in non-complexing media for developing the coordination chemistries of Am(V) and Am(VI) and, more importantly, for separation of americium from nuclear waste streams.

  12. Radiation-chemical behaviour of Rh(3) in perchloric and nitric acid media

    International Nuclear Information System (INIS)

    Rhodium(3) behaviour in solutions of concentrated (> 1 mol/l) nitric and perchloric acids under 60Co gamma radiation with dose rate of 3.5 Gy/s has been studied. It is shown that in case of nitrate solution irradiation by doses up to 2x104 Gy, rhodium(3) concentration does not change. Rhodium(3) proved to be stable in perchlorate solutions in case of irradiation by doses up to 3x104 Gy; however, in the presence of organic acids and alcohols its reduction to methane occurred. Kinetic characteristics of rhodium(3) reduction by ethyl alcohol by the doses up to 4x104 Gy have been ascertained, reduction mechanism being considered. 6 refs.; 4 figs.; 1 tab

  13. Low temperature fabrication of 5-10 nm SiO2/Si structure using advanced nitric acid oxidation of silicon (NAOS) method

    International Nuclear Information System (INIS)

    We have developed the advanced nitric acid oxidation of Si (NAOS) method to form relatively thick (5-10 nm) SiO2/Si structure with good electrical characteristics. This method simply involves immersion of Si in 68 wt% nitric acid aqueous solutions at 120 deg. C with polysilazane films. Fourier transform infrared absorption (FT-IR) measurements show that the atomic density of the NAOS SiO2 layer is considerably high even without post-oxidation anneal (POA), i.e., 2.28 x 1022 atoms/cm2, and it increases by POA at 400 deg. C in wet-oxygen (2.32 x 1022 atoms/cm2) or dry-oxygen (2.30 x 1022 atoms/cm2). The leakage current density is considerably low (e.g., 10-5 A/cm2 at 8 MV/cm) and it is greatly decreased (10-8 A/cm2 at 8 MV/cm) by POA at 400 deg. C in wet-oxygen. POA in wet-oxygen increases the atomic density of the SiO2 layer, and decreases the density of oxide fixed positive charges.

  14. ADSORPTION FROM AQUEOUS SOLUTION ONTO NATURAL AND ACID ACTIVATED BENTONITE

    Directory of Open Access Journals (Sweden)

    Laila Al-Khatib

    2012-01-01

    Full Text Available Dyes have long been used in dyeing, paper and pulp, textiles, plastics, leather, paint, cosmetics and food industries. Nowadays, more than 100,000 commercial dyes are available with a total production of 700,000 tones manufactured all over the world annually. About 10-15% of dyes are being disposed off as a waste into the environment after dyeing process. This poses certain hazards and environmental problems. The objective of this study is to investigate the adsorption behavior of Methylene Blue (MB from aqueous solution onto natural and acid activated Jordanian bentonite. Both bentonites are firstly characterized using XRD, FTIR and SEM techniques. Then batch adsorption experiments were conducted to investigate the effect of initial MB concentration, contact time, pH and temperature. It was found that the percentage of dye removal was improved from 75.8% for natural bentonite to reach 99.6% for acid treated bentonite. The rate of MB removal followed the pseudo second order model with a high correlation factor. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. The Langmuir isotherm model was found more representative. The results indicate that bentonite could be employed as a low cost adsorbent in wastewater treatment for the removal of colour and dyes.

  15. 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.

  16. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    OpenAIRE

    Kabljanac, Ž.; Herjavec, I.; Mikoč, K.; Vdović, D.; Ljubičić, M.; Zečević, N.

    2011-01-01

    This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comp...

  17. Modelling of nitric acid production in the Advanced Cold Process Canister due to irradiation of moist air

    International Nuclear Information System (INIS)

    This report summarises the work performed for SKB of Sweden on the modelling of nitric acid production in the gaseous environment of the Advanced Cold Process Canister (ACPC). The model solves the simultaneous chemical rate equations describing the radiation chemistry of He/Ar/N2/O2/H2O gas mixture, involving over 200 chemical reactions. The amount of nitric acid produced as a function of time for typical ACPC conditions has been calculated using the model and the results reported. 11 refs, 11 figs, 1 tab

  18. State-of-the-art for the production of nitric acid with regard to the IPPC directive

    International Nuclear Information System (INIS)

    The aim of this study is to describe state-of-the-art technologies for nitric acid production in view of the IPPC-directive. The study gives a general survey of applied technologies, starting materials, and emissions (incl. wastes and residual materials) specific to the production of nitric acid. An essential feature of the study is to point out the potential of reduction of atmospheric pollutants. Process integrated measures and end-of-pipe technologies for the reduction of air emissions are described. Cost estimates for selected end-of-pipe technologies are given. The specific situation in Austria is described. (author)

  19. Separation of uranium from solid (U, Pu, Ag) oxide analytical waste: effect of batch size and nitric acid molarity

    International Nuclear Information System (INIS)

    Earlier we had studied the effect of leaching of a solid analytical waste of (U,Pu)O2 and AgCl with nitric acid of different molarities for identical as well as varying time intervals and the effect of leaching of this waste with nitric acid as a function of batch size (5,10, 20 g). In the present work, the effect of multistep leaching of a 25 g lot of this analytical waste with 4 and 8 M HNO3 was studied. The concentrations of U, Pu and silver were determined using ICP-AES. The results are discussed in this report. (author)

  20. The effect of nitric acid exposure on Galileo spacecraft titanium alloy Ti-6Al-4V propellant tanks

    Science.gov (United States)

    Hsieh, Cheng; O'Donnell, Tim; Yavrouian, Andre

    1990-01-01

    The Ti-6Al-4V-constructed retropropulsion-module tanks of the Galileo spacecraft were purged with nitrogen tetroxide in order to wait out a major launch rescheduling; nitric acid is among the residual products of such an operation. A test program was conducted on representative samples to ascertain the fracture toughness and stress corrosion threshold of the tanks' material, in view of Space Shuttle safety and mission-reliability requirements. It was found that the tanks' structural integrity was not degraded by nitric acid exposure.

  1. Extraction of U(VI) and Th(IV) in nitric acid medium with N,N,N',N'-tetrahexylsuccinylamide

    International Nuclear Information System (INIS)

    The extraction mechanisms of U(VI) and Th(IV) in nitric acid solutions with N,N,N',N'-tetrahexylsuccinylamide (THSA) were described. The effects of nitric acid concentration, THSA concentration and temperature on the distribution coefficients of U(VI) and Th(IV), and the back extraction behaviours of U(VI) and Th(IV) from organic phase were studied. The compositions of the complex are found to be UO2(NO3)2·THSA and Th(NO3)4·2THSA. The equilibrium constants and thermodynamical functions of the extraction reactions have been calculated

  2. Isolation of actinides and lanthanides by flotation from nitric acid solutions in the form of the complexes with diphosphinedioxides

    International Nuclear Information System (INIS)

    Isolation of europium, plutonium (4) and americium by ionic flotation from nitric acid solutions (1-5 mol/l HNO3), using diphosphinedioxides as surfactant-precipitator, was investigated. Increase in the metal isolation degree with an increase in flotation agent consumption was ascertained. When flotation agent is in excess, required for precipitation completeness, the metals studied are noticeably extracted from moderately concentrated solutions of nitric acid (3-3.5 mol/l), moreover, tolyl-containing diphosphinedioxide per one flotation operation extracts ∼90 % of plutonium, ∼75 % of americium and >75 % of europium

  3. Electrochemical corrosion investigations on austenitic CrNi-steels in nitric acid with and without additions of metal ions

    International Nuclear Information System (INIS)

    The aim of the present work was to develop an electrochemical short-time test procedure for detecting intergranular corrosion (IGC) susceptibility of austenitic CrNi-steels in strongly oxidizing media, as e.g. concentrated nitric acid. This procedure should cover the test parameters of the usually applied ASTM Standard Huey Test, which is performed in boiling 14.4 n nitric acid. The described electrochemical test procedure - a potentiostatic polarisation of steel specimens in the transpassive range - is presented as an alternative to the Huey Test with equivalent results, but with a reduced testing time. (orig./IHOE)

  4. 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.

  5. INTERACTION OF AQUEOUS SOLUTIONS OF CHLORINE WITH MALIC ACID, TARTARIC ACID, AND VARIOUS FRUIT JUICES, A SOURCE OF MUTAGENS

    Science.gov (United States)

    The interactions of aqueous solutions of chlorine with some fruit acids (citric acid, DL-malic acid, and L-tartaric acid) at different pH values were studied. iethyl ether extraction followed by GC/MS analysis indicated that a number of mutagens (certain chlorinated propanones an...

  6. Involvement of Nitric Oxide on Calcium Mobilization and Arachidonic Acid Pathway Activation during Platelet Aggregation with different aggregating agonists

    OpenAIRE

    Banerjee, Debipriya; Mazumder, Sahana; Kumar Sinha, Asru

    2016-01-01

    Platelet aggregation by different aggregating agonists is essential in the normal blood coagulation process, the excess of which caused acute coronary syndrome (ACS). In all cases, the activation of arachidonic acid by cycloxygenase was needed for the synthesis of thromboxane A2 (TXA2) but the mechanism of arachidonic acid release in platelets remains obscure. Studies were conducted to determine the role of nitric oxide (NO), if any, on the release of arachidonic acid in platelets. The cytoso...

  7. Transport of neodymium from nitric acid solution by non-dispersive solvent extraction using a hollow fiber contactor

    International Nuclear Information System (INIS)

    Transport behaviour of neodymium from nitric acid medium was investigated using hollow fiber non-dispersive extraction technique employing a mixture of di-nonyl phenyl phosphoric acid (DNPPA) and tri-n-octylphosphine oxide (TOPO) in petrofin as the solvent. The effect of feed acidity and Nd concentration was studied in counter current mode at a feed as well as organic phase flow rate of 100 mL/min. (author)

  8. Ion flotation behaviour of thirty-one metal ions in mixed hydrochloric/nitric acid solutions.

    Science.gov (United States)

    Hualing, D; Zhide, H

    1989-06-01

    The ion flotation of 31 metal ions in hydrochloric/nitric acid solution with the cationic surfactant cetylpyridinium chloride was investigated. A 25-ml portion of 0.27-2.87 x 10(-4)M metal ion and 1.8-6.0 x 10(-4)M cetylpyridinium chloride solution in 0.17-3.4M acid mixture ([HCl]:[HNO(3)] = 2.4:1) was subjected to flotation in a cell, 22.5 cm high and 4.0 cm in diameter, for 5 min, with nitrogen bubbles. Ir(IV), Pt(IV), Ge(IV), Sn(IV), Bi(III), Au(III), Tl(III), Pd(II) and Sn(II) were floated from solution in 95-100% yield; Ru(III), Rh(III), Ir(III), Hg(II), Ag(I) and Tl(I) were partly floated, while Cr(VI), Ti(IV), Zr(IV), Ga(III), In(III), Fe(III), Sb(III), Al(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), CD(II) and Pb(II) were floated with less than 20% yield. The flotation behaviour of these metal ions in the mixed acid system was compared with that in hydrochloric acid. The flotation is more efficient in the mixed acid system. PMID:18964771

  9. Synthesis and characterization of N,N,N',N'-tetrabutylsuccinamide as extractant for uranium(VI) and thorium(IV) ions from nitric acid solution

    International Nuclear Information System (INIS)

    Synthesis and characterization of N,N,N',N'-tetrabutylsuccinamide (TBSA) was carried out and used for the extraction of U(VI) and Th(IV) from nitric acid solutions. Toluene was found to be the most suitable diluent for TBSA compared with the other diluents tested. Extraction distribution ratios (D) of U(VI) and Th(IV) have been studied as a function of aqueous HNO3 concentrations, NO3- ion concentration, TBSA concentration and temperature. The results obtained indicated that U(VI) and Th(IV) are mainly extracted as UO2(NO3)2 x 2TBSA and Th(NO3)4 x TBSA, respectively, and the IR spectra of the extracted species have been investigated. The values of thermodynamic functions have been calculated. Back-extraction of U(VI) and Th(IV) from organic phases was also studied. (author)

  10. Analysis of a two-phase system of mass transfer and electro-reduction of uranium(VI) in nitric acid-hydrazine media

    International Nuclear Information System (INIS)

    Simulation for a dynamic analysis of the electrolytic preparation of U(IV) in two-phases system, which consisted of mass transfer of U(VI) from TBP phase into HNO3 solution and electrolytic reduction of U(VI) to U(IV) at a cathode in aqueous phase, was carried out in order to establish the most suitable operating condition and best electrode area as basic design data for the system. It was found that maintaining an appropriate mass transfer rate was more significant rather than enlarging the surface area of the cathode for more effective production yield of U(IV). The electrode area and the operation time affected deeply the production composition of U(IV) in the resulting aqueous phase. And optimal electrode areas were evaluated to meet production criteria of U(IV) of resulting solution in several system conditions. Though about 0.37M HNO3 was preferable to prepare the solution of U(IV), nitric acid concentration should be higher than 0.5M to prevent a hydrolysis of U(IV) in the aqueous phase. 6 figs., 24 refs. (Author)

  11. 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.

  12. Kinetics of reduction of nitric acid by electrochemical method and validation of cell design for plant application

    International Nuclear Information System (INIS)

    Employing electrochemical method, the concentration of nitric acid had been reduced from 4 to about 0.5 M, under constant current/potential conditions in batch mode, for the purpose of optimizing the process parameters for the destruction of nitric acid in radioactive liquid waste, with good energy efficiency. Based on the rate constants determined from the batch process, a cell assembly in cylindrical configuration was designed for the electro-reduction of nitric acid in continuous mode, in radioactive environment. The steady state concentration of the acid at the outlet was compared with that concentration calculated using model equation and the agreement between the two sets of data was found to be reasonable. Cyclic voltammetric runs were recorded to understand the reduction behavior of nitric acid on platinum electrode. The results revealed the reduction of nitrate ion to be a quasi–reversible process and for the scan rate of 0.1 V s−1, values of 3.3 × 10−6 cm2 s−1 and 1.37 × 10−3 cm s−1 were computed for the diffusion coefficient and heterogeneous electron transfer rate constant, respectively

  13. Formation of nitric and organic acids by the irradiation of ground water in a spent fuel repository

    International Nuclear Information System (INIS)

    The formation of nitric acid has been reported in the literature, e g in connection with studies of glass leaching during irradiation. These experiments were carried out in order to evaluate the behaviour of glass as a matrix for highly radioactive waste. The presence of a nitrogen containing gas phase has been found to be important for the yield of the reaction. The formation of organic acids by radiolysis of carbonate solutions has been reported. The literature on the formation of organic and nitric acids have been surveyed and discussed. A conservative estimate of the formation of nitric and organic acids has been made based on dissolved nitrogen and carbonate in groundwater in a spent fuel repository. Outside a 10 cm thick copper canister containing spent fuel (the Swedish KBS-3 concept) the conservatively estimated total production of nitric, formic, and oxalic acids after 1 million years is 0.08 mol HNO 3, 0.06 mol HCOOH, and 0.04 mol (COOH) 2. For a thinner version of this canister with a wall thickness of only 1 cm, the conservatively estimated total production after 1 million years is 5 mol HNO 3, 4 mol HCOOH, and 3 mol (COOH) 2. (Author)

  14. The extraction of uranium (VI) and plutonium (IV) from nitric acid solutions with N,N-dialkyl substituting amides

    International Nuclear Information System (INIS)

    The use of N,N-di-2-methylheptyl acetamide (DMHAA),N,N-di-butylbutylamide(DBBA) and N,N-di-butylheptylamide(DBHA) as extractants for the extraction of nitric acid, U(VI) and Pu(IV) from the nitric acid solution has been investigated. The molar ratios of DBHA-HNO3 and DBHA-UO2(NO3)2 complexes are found to be 1:1 and 2:1 respectively. The complexes of both nitric acid and uranyl nitrate with these amides are highly soluble in aromatic diluent such as toluene without any formation of the third phase. The results show that, by modifying the length of the substitute chain and the degree of branch chain, some substituted amides might be found with which U(VI) and Pu(IV) could be co-extracted at moderate nitric acid solution and Pu(IV) could be preferably stripped at low acidity, and the separation of U(VI) and Pu(IV) could be accomplished without reductant of U(VI) and Pu(IV) in amide extraction

  15. Nitric oxide metabolism and indole acetic acid biosynthesis cross-talk in Azospirillum brasilense SM.

    Science.gov (United States)

    Koul, Vatsala; Tripathi, Chandrakant; Adholeya, Alok; Kochar, Mandira

    2015-04-01

    Production of nitric oxide (NO) and the presence of NO metabolism genes, nitrous oxide reductase (nosZ), nitrous oxide reductase regulator (nosR) and nitric oxide reductase (norB) were identified in the plant-associated bacterium (PAB) Azospirillum brasilense SM. NO presence was confirmed in all overexpressing strains, while improvement in the plant growth response of these strains was mediated by increased NO and indole-3-acetic acid (IAA) levels in the strains. Electron microscopy showed random distribution to biofilm, with surface colonization of pleiomorphic Azospirilla. Quantitative IAA estimation highlighted a crucial role of nosR and norBC in regulating IAA biosynthesis. The NO quencher and donor reduced/blocked IAA biosynthesis by all strains, indicating their common regulatory role in IAA biosynthesis. Tryptophan (Trp) and l-Arginine (Arg) showed higher expression of NO genes tested, while in the case of ipdC, only Trp and IAA increased expression, while Arg had no significant effect. The highest nosR expression in SMnosR in the presence of IAA and Trp, along with its 2-fold IAA level, confirmed the relationship of nosR overexpression with Trp in increasing IAA. These results indicate a strong correlation between IAA and NO in A. brasilense SM and suggest the existence of cross-talk or shared signaling mechanisms in these two growth regulators. PMID:25700632

  16. Optical properties of chitosan in aqueous solution of L- and D-ascorbic acids

    Science.gov (United States)

    Malinkina, Olga N.; Shipovskaya, Anna B.; Kazmicheva, Olga F.

    2016-04-01

    The optical properties of aqueous chitosan solutions in L- and D-ascorbic acids were studied by optical rotatory dispersion and spectrophotometry. The specific optical rotation [α] of all chitosan solutions tested was positive, in contrast to aqueous solutions of the ascorbic acid enantiomers, which exhibit an inverse relationship of [α] values. Significant differences in the absolute values of [α] of the chitosan solutions at polymer-acid ratios exceeding the equimolar one were found.

  17. Extraction of lanthanide(III) and uranyl(VI) from nitric acid solution by malonamides

    International Nuclear Information System (INIS)

    The extractive properties of two malonamide extractants, DMDBO3NPDA and DMDBMA were investigated for the extraction of lanthanide(III) and uranyl(VI) ions in benzene-nitric acid systems. It was found that DMDBO3NPDA has a higher extractive capacity than DMDBMA. The difference in their extracting capacities is discussed, based on the enthalpy changes for the extraction reactions and IR data for complexes of metal nitrates with malonamides. In addition, the applicability of a mixed solvent of n-dodecane and some aliphatic alcohols as a diluent for DMDBO3NPDA was examined. the longer the carbon chain and the higher the concentration of the aliphatic alcohol, the more the phase compatibility improves. The distribution ratios of neodymium(III) ion increase with an increase in the carbon chain length of linear aliphatic alcohol and with a decrease in its concentration

  18. Pb(II leaching from waste CRT funnel glass in nitric acid solutions

    Directory of Open Access Journals (Sweden)

    A. Strzałkowska

    2012-12-01

    Full Text Available Purpose: The paper presents experimental results of Pb (II leaching from waste CRT funnel glass using solution of nitric acid (V . This work focused on examining the impact of concentration and particle size on the leaching percentage of Pb (II from funnel glass.Design/methodology/approach: Material for the investigation was crushed and sieved. Leaching was carried out using working solutions pfrom co repared ncentrated HNO3 and mechanical stirrer.Findings: The received results show the possibility of find the parameters of leaching that could remove the whole Pb(II from funnel glass.Practical implications: Results after additional research can be applicate by glass industry.Originality/value: Worked out technologies can be used in glass recycling and production.

  19. Potentiality of uranium biosorption from nitric acid solutions using shrimp shells.

    Science.gov (United States)

    Ahmed, S H; El Sheikh, E M; Morsy, A M A

    2014-08-01

    Biosorption has gained important credibility during recent years because of its good performance and low cost. This work is concerned with studying the potentiality of the chitin component of the shrimp shells for uranium biosorption from nitric acid liquid solutions. The structural characteristics of the working chitin have been determined via Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology was examined using Scanning Electron Microscopy (SEM). The adsorption capacity of biomass was investigated experimentally. The influence of contact time, pH, metal ion concentration, solution volume to mass ratio and temperature were evaluated and the results were fitted using adsorption isotherm models. The kinetic of uranium biosorption was also investigated as well as biosorption thermodynamic. PMID:24704766

  20. Sorption of uranium and thorium ions from nitric acid solution using HDEHP-Impregnated activated carbon

    International Nuclear Information System (INIS)

    Equilibrium measurements on the sorption of uranium and thorium ions from nitric acid solutions using di(2-ethyl hexyl) phosphoric (HDEHP) impregnated activated carbon have been done using batch technique. Experimental isotherms, Ferundlish, and Dubinin-Radushkevich (D-R) isotherm models. Of the models tested, D-R expression was found to represent the isotherms of both ions better over Th entire concentration range investigated than either Langmuir or Freundlish model. The changes in standard thermodynamic quantities (viz. Δ H, Δ S, and Δ G) were calculated and the maximum adsorption capacity of HDEHP impregnated carbon together with the mean free energy of both studied ions were determined using D-R approach

  1. Adsorption of butanol vapor on active carbons with nitric acid hydrothermal modification.

    Science.gov (United States)

    Cao, Yuhe; Wang, Keliang; Wang, Xiaomin; Gu, Zhengrong; Gibbons, William; Vu, Han

    2015-11-01

    Butanol can be produced from biomass via fermentation and used in vehicles. Unfortunately, butanol is toxic to the microbes, and this can slow fermentation rates and reduce butanol yields. Butanol can be efficiently removed from fermentation broth by gas stripping, thereby preventing its inhibitory effects. Original active carbon (AC) and AC samples modified by nitric acid hydrothermal modification were assessed for their ability to adsorb butanol vapor. The specific surface area and oxygen-containing functional groups of AC were tested before and after modification. The adsorption capacity of unmodified AC samples was the highest. Hydrothermal oxidation of AC with HNO3 increased the surface oxygen content, Brunauer-Emmett-Teller (BET) surface area, micropore, mesopore and total pore volume of AC. Although the pore structure and specific surface area were greatly improved after hydrothermal oxidization with 4M HNO3, the increased oxygen on the surface of AC decreased the dynamic adsorption capacity. PMID:26291412

  2. Studies of dissolution solutions of ruthenium metal, oxide and mixed compounds in nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Mousset, F.; Eysseric, C.; Bedioui, F

    2004-07-01

    Ruthenium is one of the fission products generated by irradiated nuclear fuel. It is present throughout all the steps of nuclear fuel reprocessing-particularly during extraction-and requires special attention due to its complex chemistry and high {beta}{gamma} activity. An innovative electro-volatilization process is now being developed to take advantage of the volatility of RuO{sub 4} in order to eliminate it at the head end of the Purex process and thus reduce the number of extraction cycles. Although the process operates successfully with synthetic nitrato-RuNO{sup 3+} solutions, difficulties have been encountered in extrapolating it to real-like dissolution solutions. In order to better approximate the chemical forms of ruthenium found in fuel dissolution solutions, kinetic and speciation studies on dissolved species were undertaken with RuO{sub 2},xH{sub 2}O and Ru{sup 0} in nitric acid media. (authors)

  3. Study on Purification Diatomite with nitric acid by Thermal Closed System

    Directory of Open Access Journals (Sweden)

    Kuang Meng

    2016-01-01

    Full Text Available In this research, a purification approach using nitric acid leaching at thermal closed system was developed to improve the porous structure of raw diatomite by removal of impurities from its surface and clogged pores. The feasibility and efficiency of this approach were determined by XRF for chemical constitution of diatomite, SEM for morphology and BET for specific surface area of purified diatomite. The investigations indicated that the content of SiO2 was in order of 85.14% for raw diatomite and 98% for purified diatomite, the content of Fe2O3 decreases after purified; the integrity of the porous structure was confirmed by SEM, and increase in specific surface area from 18m2·g-1 to 36m2·g-1.

  4. Vapor pressures of solid hydrates of nitric acid - Implications for polar stratospheric clouds

    Science.gov (United States)

    Worsnop, Douglas R.; Fox, Lewis E.; Zahniser, Mark S.; Wofsy, Steven C.

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO3.H2O, HNO3.2H2O, HNO3.3H2O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO3.2H2O may be favored in polar stratospheric clouds over the slightly more stable HNO3.3H2O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO3.2H2O and HNO3.3H2O. Vapor transfer from HNO3.2H2O to HNO3.3H2O could be a key step in the sedimentation of HNO3, which plays an important role in the depletion of polar ozone.

  5. Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds.

    Science.gov (United States)

    Worsnop, D R; Zahniser, M S; Fox, L E; Wofsy, S C

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone. PMID:17757475

  6. Supercritical fluid extraction of uranium from nitric acid medium and tissue paper matrix

    International Nuclear Information System (INIS)

    Supercritical fluid extraction (SFE) is a novel technique for metal ion extraction, which offers a promising alternate to the conventional extraction process. The technique has advantage of minimization of radioactive liquid waste. In the present study, supercritical CO2 containing small amount of TBP/TOPO as co-solvent were employed for uranium extraction. Uranium extraction efficiency of ∼ 98% was achievable from nitric acid medium employing TBP as co-solvent. However, uranium could be extracted to nearly same extent with lesser amount (1 ml) of TOPO. In SFE of uranium from tissue paper matrix extraction efficiency of 70% was obtained with TBP as co-solvent. Whereas nearly complete uranium extraction (∼99%) was achievable from tissue paper with TOPO as co-solvent. (author)

  7. Influence of different diluents on thorium extraction and third-phase formation from nitric acid medium

    International Nuclear Information System (INIS)

    Advanced heavy water reactor (AHWR) is being developed in India for the utilization of vast resources of thorium for power generation. The reprocessing of the irradiated AHWR fuel is quite challenging in view of the presence of Th, U and Pu along with fission products in the feed solution. This paper compares thorium extraction/third-phase formation behavior of TBP and DHOA dissolved in different diluents viz. n-dodecane, normal paraffinic hydrocarbon (NPH), Shelsol D 70 (SS D 70, 40 % aromatic), and Solvsso 100 (∼ 95-100 % aromatic) as a function of nitric acid concentration. The work compares the performance of SS D 70 and Solvsso 100 having aromatic components vis-à-vis n-dodecane and NPH towards Th(IV) extraction/third-phase using TBP and DHOA as extractants. It is observed that presence of aromatic component in the diluent helps in increasing the Th(IV)-LOC value

  8. Studies of dissolution solutions of ruthenium metal, oxide and mixed compounds in nitric acid

    International Nuclear Information System (INIS)

    Ruthenium is one of the fission products generated by irradiated nuclear fuel. It is present throughout all the steps of nuclear fuel reprocessing-particularly during extraction-and requires special attention due to its complex chemistry and high βγ activity. An innovative electro-volatilization process is now being developed to take advantage of the volatility of RuO4 in order to eliminate it at the head end of the Purex process and thus reduce the number of extraction cycles. Although the process operates successfully with synthetic nitrato-RuNO3+ solutions, difficulties have been encountered in extrapolating it to real-like dissolution solutions. In order to better approximate the chemical forms of ruthenium found in fuel dissolution solutions, kinetic and speciation studies on dissolved species were undertaken with RuO2,xH2O and Ru0 in nitric acid media. (authors)

  9. Sorption of Pu(IV) from nitric acid by bifunctional anion-exchange resins

    International Nuclear Information System (INIS)

    Anion exchange is attractive for separating plutonium because the Pu(IV) nitrate complex is very strongly sorbed and few other metal ions form competing anionic nitrate complexes. The major disadvantage of this process has been the unusually slow rate at which the Pu(IV) nitrate complex is sorbed by the resin. The paper summarizes the concept of bifunctional anion-exchange resins, proposed mechanism for Pu(IV) sorption, synthesis of the alkylating agent, calculation of Kd values from Pu(IV) sorption results, and conclusions from the study of Pu(IV) sorption from 7M nitric acid by macroporous anion-exchange resins including level of crosslinking, level of alkylation, length of spacer, and bifunctional vs. monofunctional anion-exchange resins

  10. Simultaneous extraction of U and Zr using HDEHP impregnated XAD-7 resin in nitric acid medium

    International Nuclear Information System (INIS)

    Feasibility of separating U and Zr from U-Zr alloys using HDEHP impregnated XAD-7 resin was explored in the present study with a view to obtain a sample solution free from matrix elements suitable for carrying out ICP-MS analysis of lanthanides at trace concentrations. Initially, the distributions of U, Zr and lanthanides in the impregnated resin were investigated with different nitric acid concentrations. The separated fractions were analyzed by ICP-MS for trace lanthanides whereas ion chromatography was employed for quantifying U and Zr. It was observed that at 4M HNO3 medium U exhibited high distribution whereas lanthanides showed least distribution in the resin. Zirconium showed significant distribution in 4M HNO3. Hence, 4M HNO3 was found to be optimal in order to extract U and Zr simultaneously. However, heavy rare earths such as Tm, Yb and Lu showed significant Kd values leading to their poor recovery. (author)

  11. Catalytic decomposition of nitrous oxide from nitric acid production tail gases. Investigation of inhibition effects. Executive summary

    International Nuclear Information System (INIS)

    Nitric acid production is an important source of nitrous oxide, one of the green-house gases. Catalytic decomposition of N2O in nitric acid tail-gases might be a possibility for emission reduction, but technology is not yet available. As a part of development of suitable catalytic systems, research was performed, aiming at: gaining an improved understanding of catalytic decomposition of N2O and the inhibiting effects of NO, NO2, H2O and O2; and preparing a 'go-no go' decision whether or not to proceed with subsequent re-search and development and if yes, to indicate what technology further development should aim for. Due to the presence of NOx and water in the nitric acid tail gases, catalytic decomposition proves not to be feasible at temperatures below 350C. At higher temperatures possibilities do exist and a number of promising catalysts are identified. These are active (80 - 100 % conversion) in the temperature range of 400 - 500C and under simulated tail gas conditions. Considering process conditions only (temperatures and composition of the tail-gases), the catalysts studied (pref. the Rh/Al2O3 types) could be in principle applied successfully in all Dutch nitric acid plants

  12. Overexpression of cationic amino acid transporter-1 increases nitric oxide production in hypoxic human pulmonary microvascular endothelial cells

    OpenAIRE

    Cui, Hongmei; Chen, Bernadette; Chicoine, Louis G.; Nelin, Leif D.

    2011-01-01

    1. The endogenous production of and/or the bioavailability of nitric oxide (NO) is decreased in pulmonary hypertensive diseases. L-arginine (L-arg) is the substrate for NO synthase (NOS). L-arg is transported into cells via the cationic amino acid transporters (CAT), of which there are two isoforms in endothelial cells, CAT-1 and CAT-2.

  13. Nitric Acid Deposition following an Astrophysical Ionizing Radiation Event is below Critical Loads for Terrestrial and Freshwater Ecosystems

    CERN Document Server

    Melott, Ben Neuenswander Adrian

    2014-01-01

    Nitric acid rainout is one of the effects of an astrophysical ionizing radiation event. The predicted values of nitrate rainout from previous work for a typical gamma ray burst (GRB) within our galaxy serve as an extreme example and are shown to be below critical loads of eutrophication and acidification for ecoregions in Europe and the US.

  14. PKCa Agonists Enhance the Protective Effect of Hyaluronic Acid on Nitric Oxide-Induced Apoptosis of Articular Chondrocytes in Vitro

    Directory of Open Access Journals (Sweden)

    Jian-lin Zhou

    2013-12-01

    The results may be showed that PKCa regulate the expresion of caspase-3, which contribute to the apoptosis of chondrocytes induced by NO. PKC α agonists enhance the protective effect of hyaluronic acid on nitric oxide-induced articular chondrocytes apoptosis.

  15. Ammonium nitrate evaporation and nitric acid condensation in DMT CCN counters

    Science.gov (United States)

    Romakkaniemi, S.; Jaatinen, A.; Laaksonen, A.; Nenes, A.; Raatikainen, T.

    2014-05-01

    The effect of inorganic semivolatile aerosol compounds on the cloud condensation nucleus (CCN) activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big a fraction of semivolatiles is evaporated from particles after entering but before particle activation in the DMT-CCN counter? (2) How much can the CCN activity be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? Both experimental and modelling results show that the evaporation of ammonia and nitric acid from ammonium nitrate particles causes a 10 to 15 nm decrease to the critical particle size in supersaturations between 0.1% and 0.7%. On the other hand, the modelling results also show that condensation of nitric acid or similar vapour can increase the CCN activity of nonvolatile aerosol particles, but a very high gas phase concentration (as compared to typical ambient conditions) would be needed. Overall, it is more likely that the CCN activity of semivolatile aerosol is underestimated than overestimated in the measurements conducted in ambient conditions.

  16. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    International Nuclear Information System (INIS)

    Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO4/HNO3. • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO4/HNO3 treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process

  17. Investigation on surface structure of potassium permanganate/nitric acid treated poly(tetrafluoroethylene)

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Congli; Liu, Shuling; Gong, Tianlong; Gu, Aiqun; Yu, Zili, E-mail: ziliyu@scu.edu.cn

    2014-10-30

    Highlights: • A new transformation (conversion) mechanism of PTFE surface from a hydrophobicity to a hydrophilicity was proposed through the treatment of KMnO{sub 4}/HNO{sub 3}. • Chemical reactions or defluorination of PTFE described in the reported paper was testified to be a misconceived conclusion by the combination of several testing measurements (IR, XPS, XRD and so on) in our present work. • Deposition of manganese oxide and/or manganese hydroxide on PTFE surface contributed to the hydrophilic property of the modified PTFE with KMnO{sub 4}/HNO{sub 3} treated. • The deposition thickness on the modified PTFE surface was about 5 μm, which was significantly helpful in enhancing the adhesive strength of PTFE with other materials. - Abstract: In the previous articles concerning the treatment of poly(tetrafluoroethylene) (PTFE) with potassium permanganate/nitric acid mixture, the conversion of a hydrophobic to a hydrophilic surface was partially assigned to the defluorination of PTFE and then the introduction of carbonyl and hydroxyl groups into the defluorinated sites. In the present work, PTFE sheets were treated with potassium permanganate/nitric acid, and the surfaces before and after treatment were comparatively characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface sediments of the treated PTFE were also determined by atomic absorption spectroscopy (AAS). The results indicate that the conversion of the hydrophobicity to the hydrophilicity on the modified PTFE surface is mainly due to the deposition of hydrophilic manganese oxides which covered the fluorocarbon surface, and no detectable chemical reactions of PTFE occur in the treating process.

  18. Optimization of the nitrous vapors experimental conditions production by nitric acid electrochemical reduction; Optimisation des conditions operatoires de production de vapeurs nitreuses par reduction electrochimique d`acide nitrique

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, M.

    1996-11-22

    Gaseous nitrogen oxides (NO and NO{sub 2}) involved as oxidizing agents in nuclear fuel reprocessing can be produced by electrochemical reduction of nitric acid. This is an interesting alternative to the existing process because no wastes are generated. voltammetric studies on a platinum electrode show that two reduction potential regions are observed in concentrated nitric acid solutions, between 0,05 V{sub SHE} and between 0,5 V{sub SHE} and 1 V{sub SHE}. The highest potential region reduction mechanism was studied by: classical micro-electrolysis methods, macro-electrolysis methods, infrared spectroscopy coupled to electrochemistry. It was determined that the origin of nitric acid reduction is the electrochemical reduction of nitrous acid in nitric oxide which chemically reduces nitric acid. This reaction produces nitrous acid back which indicate an auto-catalytic behaviour of nitric acid reduction mechanism. Nitrogen dioxide evolution during nitric reduction can also explained by an other chemical reaction. If the potential value of platinum electrode is above 0,8 V{sub SHE}, products of the indirect nitric acid reduction are nitrous acid, nitrogen oxide and nitrogen dioxide. Below this value nitric oxide can be reduced in nitrous oxide. Thus the potential value is the most important parameter for the nitrogen oxides production selectivity. However, owing to the auto-catalytic character of the reduction mechanism, potential value can be controlled during intentiostatic industrial electrolysis. (author). 91 refs.

  19. Mass transfer studies in miniature Rotating Disc Contactor (RDC) with 30% TBP/nitric acid biphasic system

    International Nuclear Information System (INIS)

    The rotating disc contactor is the widely used liquid-liquid extraction equipment for its high throughput and efficiency. In this work mass transfer performance of the miniature RDC column for the 30% TBP/nitric acid biphasic system was studied in terms of the operating variables such as rotor speed and flow rate of the aqueous and organic phase. The RDC column used in the experiments was shown. The column shell is made up of thick glass having diameter of 10.5 cm and height 100 cm. The rotor diameter is 5.3 cm and stator opening diameter is 6.3 cm. Totally 25 number of rotor discs were welded in the rotating shaft. This shaft was aligned in such a way that each rotor was placed in the centre of the compartment formed in between the two stator rings. The experiments were carried out to study the effect of rotor speed and superficial velocity of the dispersed and continuous phase on mass transfer efficiency. The organic solvent was made as the continuous phase and O/A ratio was set as 4 in both the continuous to dispersed phase(c-d) and dispersed to continuous phase (d-c) mass transfer experiments. The Number of Transfer Units (NTU) was estimated based on the solvent phase. The graphical representation of NTU was shown. The NTU value was observed as 4 and 3 respectively for extraction and stripping at the combined through put of 60 L/h and the rotor speed of 1000 rpm. This corresponds to the Height of Transfer Unit (HTU) value of 15 cm and 20 cm respectively for d-c and c-d mass transfer. The estimated overall mass transfer coefficient was increasing with rotor speed and superficial velocity of the liquid phases. The overall mass transfer coefficient also increases with increase in hold up

  20. Alpha radiolysis of nitric acid and sodium nitrate with 4He2+ beam of 13.5 MeV energy

    International Nuclear Information System (INIS)

    A study of aqueous nitric acid solution alpha radiolysis was performed through experiments carried out at a cyclotron facility, where a helion beam with an energy of 13.5 MeV could be delivered into the solution. The effects of nitrate and hydronium ions on the formation yields of hydrogen peroxide and nitrous acid, G(H2O2) and G(HNO2), were studied. The results showed that G(H2O2) decreases linearly with increasing nitrate ion concentration. On the other hand, G(HNO2) increases with the nitrate ion concentration until it reaches a plateau for nitric acid concentrations higher than 2 mol L–1. It was also found that an increase of hydronium ion concentration has a favorable effect on G(H2O2) and G(HNO2). Furthermore, it appears that these effects are additive and that the variations of G(H2O2) and G(HNO2) can be described by two parametric expressions, as a function of the nitrate and hydronium ion concentrations. - Highlights: • G(H2O2) decreases linearly with increasing nitrate ion concentrations. • G(H2O2) increases considerably with increasing acidity (up to [H+]=0.5 mol L−1). • G(HNO2) increases with increasing nitrate and hydronium concentrations until a plateau is reached. • The effects of nitrate and hydronium ions on G(H2O2) and G(HNO2) are additive

  1. Activation of Carbonyl-Containing Molecules with Solid Lewis Acids in Aqueous Media

    Energy Technology Data Exchange (ETDEWEB)

    Román-Leshkov, Yuriy [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Chemical Engineering; Davis, Mark E. [California Inst. of Technology (CalTech), Pasadena, CA (United States). Chemical Engineering

    2011-09-28

    Current interest in reacting carbonyl-containing molecules in aqueous media is primarily due to the growing emphasis on conversion of biomass to fuels and chemicals. Recently, solid Lewis acids have been shown to perform catalytic reactions with carbonyl-containing molecules such as sugars in aqueous media. Here, catalysis mediated by Lewis acids is briefly discussed, Lewis acid solids that perform catalysis in aqueous media are then described, and the review is concluded with a few comments on the outlook for the future.

  2. Synergistic hypergolic ignition of blends of dienes and dienophiles with red fuming nitric acid as oxidizer

    Energy Technology Data Exchange (ETDEWEB)

    Panda, S.P.; Kulkarni, S.G.; Prabhakaran, C.

    1989-04-01

    Synergistic hypergolic ignition of several fuel blends and mixtures with red fuming nitric acid (RFNA) as oxidizer has been reported previously. The liquid fuels consisted of blends of 3-carene, cyclopentadiene, or norbornadiene with cardanol in the weight ratio 70:30 for the first two and 85:15 for norbornadiene. In all these cases, synergism in ignition was believed to be due to the fast and exothermic oligomerization of 3-carene, cyclopentadiene, and norbornadiene in the presence of acid. The exothermicity of the systems was enhanced by the addition of cardanol to the unsaturation of oligomers, leading to the formation of highly oxidizable phenolic ethers. Two more important reactions at the preignition stage were nitration and oxidation of the ethers leading to the production of gaseous combustibles and heat. In this case, an attempt has been made to extend the range of possible preignition reactions by introducing diene-dienophile Diels-Alder cycloaddition with low activation energy by replacing cardanol with furfuryl alcohol or furfurylideneacetone having a furan ring to behave as acid polymerizable dienes in the above systems.

  3. Hydrogen generation in SRAT with nitric acid and late washing flowsheets

    International Nuclear Information System (INIS)

    Melter feed preparation processes, incorporating a final wash of the precipitate slurry feed to Defense Waste Processing Facility (DWPF) and a partial substitution of the SRAT formic acid requirement with nitric acid, should not produce peak hydrogen generation rates during Cold Chemical Runs (CCR's) and radioactive operation greater than their current, respective hydrogen design bases of 0.024 lb/hr and 1.5 lb/hr. A single SRAT bench-scale process simulation for CCR-s produced a DWPF equivalent peak hydrogen generation rate of 0.004 lb/hr. During radioactive operation, the peak hydrogen generation rate will be dependent on the extent DWPF deviates from the nominal precipitate hydrolysis and melter feed preparation process operating parameters. Two actual radioactive sludges were treated according to the new flowsheets. The peak hydrogen evolution rates were equivalent to 0.038 and 0.20 lb/hr (DWPF scale) respectively. Compared to the formic acid -- HAN hydrolysis flowsheets, these peak rates were reduced by a factor of 2.5 and 3.4 for Tank 15 and Tank 11 sludges, respectively

  4. Integrating nitric oxide into salicylic acid and jasmonic acid/ethylene plant defense pathways

    DEFF Research Database (Denmark)

    Mur, Luis A J; Prats, Elena; Pierre, Sandra;

    2013-01-01

    Plant defence against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defence responses...

  5. Application of Primary Abatement Technology for Reduction of N2O Emmision in Petrokemija Nitric Acid Production

    Directory of Open Access Journals (Sweden)

    Ćosić, L.

    2013-01-01

    Full Text Available Industrial nitric acid production by oxidation of gaseous ammonia with Ostwald procedure produces an unwanted by-product – colorless nitrous oxide, N2O. As emission of N2O represents a very serious problem due of its huge contribution to global warming, certain measures focused on its maximum reduction should be undertaken. Minimization of N2O emission in nitric acid production can be achieved in different parts of the process flow, depending on the applied available technologies. For the abatement of N2O emissions in Petrokemija's nitric acid production processes from the list of the best available technologies chosen were primary and secondary abatement technologies. The mentioned ensures reduction of N2O by use of improved selective heterogeneous catalysts in the step of gaseous ammonia oxidation. Precious metals in the shape of gauzes are used as selective heterogeneous catalyst in primary technology, while in the case of secondary technology the Fe2 O3 catalyst on Al2O3 support in the shape of spherical pellets is chosen. Shown is the application of primary technology for the abatement of N2O in both nitric acid production facilities and their comparison with classical heterogeneous catalyst and preparation for the installation of secondary selective catalyst. N2O emissions with the application of primary technology in both production facilities were reduced from 12 kg of N2O to 7 kg of N2O per ton of pure HNO3. With the primary reduction in N2O emissions the foundation was established for further reduction with the secondary technology to the final value of 0.7 kg of N2O per ton of pure HNO3, which represents mass concentration in the tail gas below 200 mg m-3 (at n. c.. With the applied technologies for the abatement of N2O emissions in Petrokemija's nitric acid production the future prescribed emission limit value will be satisfied.

  6. N,N-dialkyl-2-hydroxyacetamides for modifier-free separation of trivalent actinides from nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Prathibha, T.; Kumaresan, R.; Selvan, B. Robert; Venkatesan, K.A.; Antony, M.P.; Vasudeva Rao, P.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.

    2016-07-01

    The alkyl derivatives of N,N,-dialkyl-2-hydroxyacetamide (DAHyA), namely, N,N,-dihexyl-2-hydroxyacetamide (DHHyA), N,N,-dioctyl-2-hydroxyacetamide (DOHyA), N,N,-didecyl-2-hydroxyacetamide (DDHyA), were synthesized and characterized by FT-IR, and NMR spectroscopy. The extraction behaviour of Am(III) in a solution of DAHyA in n-dodecane was studied as a function of various parameters to evaluate the feasibility of using DAHyA for partitioning of trivalent actinides from high-level liquid waste (HLLW). The distribution ratio of Am(III) (D{sub Am(III)}) in 0.1 M DAHyA/n-DD increased from 10{sup -4} to > 200 with increase in nitric acid concentration from 1 M to 6 M. A D{sub Am(III)} value 10-70 was obtained in a nitric acid concentration range from 3-4 M. The extraction of Am(III) in 0.1 M DAHyA/n-dodecane decreased in the order DHHyA > DOHyA > DDHyA. The third-phase formation behaviour of nitric acid and neodymium (III) in 0.2 M DAHyA/n-dodecane was studied. Near stoichiometric amount of neodymium (III) can be loaded in octyl and decyl derivatives without any third-phase formation from 3-4 M nitric acid medium. Unlike other extractants, the loaded trivalent metal ion in DAHyA can be recovered even with 1 M nitric acid. Therefore, the study revealed that N,N,-dialkyl-2-hydroxyacetamides are promising candidates for partitioning the trivalent actinides from HLLW.

  7. Fatty acid-binding protein 4 impairs the insulin-dependent nitric oxide pathway in vascular endothelial cells

    OpenAIRE

    Aragonès Gemma; Saavedra Paula; Heras Mercedes; Cabré Anna; Girona Josefa; Masana Lluís

    2012-01-01

    Abstract Background Recent studies have shown that fatty acid-binding protein 4 (FABP4) plasma levels are associated with impaired endothelial function in type 2 diabetes (T2D). In this work, we analysed the effect of FABP4 on the insulin-mediated nitric oxide (NO) production by endothelial cells in vitro. Methods In human umbilical vascular endothelial cells (HUVECs), we measured the effects of FABP4 on the insulin-mediated endothelial nitric oxide synthase (eNOS) expression and activation a...

  8. Estimation of salivary nitric oxide and uric acid levels in oral squamous cell carcinoma and healthy controls

    OpenAIRE

    Varsha Salian; Farah Demeri; Suchetha Kumari

    2015-01-01

    Background: Oral squamous cell carcinoma (OSCC) being the most common head and neck cancer, involves the interplay of several free radicals and antioxidant molecules. The potential role of salivary nitric oxide (NO) and uric acid in cancer development needs to be explored as there are a few studies highlighting their association with each other and with oral cancer. Aims: The present study was designed to measure the NO and uric acid levels in the saliva of patients with OSCC as compared with...

  9. Thermophysical property characterization of aqueous amino acid salt solutions containing α-aminobutyric acid

    International Nuclear Information System (INIS)

    Highlights: • Thermophysical properties of aqueous potassium and sodium salt solutions of α-aminobutyric acid were studied. • Density, electrolytic conductivity, refractive index, and viscosity of the solution were measured. • The concentrations of amino acid salt ranges from x1 = 0.009 to 0.06. • The temperature range studied was (303.15 to 343.15) K. • The measured data were represented satisfactorily by using the applied correlations. - Abstract: In this study, density, electrical conductivity, refractive index and viscosity of aqueous potassium and sodium salt solutions of α-aminobutyric acid were presented. Measurements were done over the temperature range (303.15 to 343.15) K and atmospheric pressure for salt compositions from x1 = 0.009 to 0.062. A modified Graber et al. equation was used to correlate the density, electrical conductivity, and refractive index with temperature and composition leading to average absolute deviations (AAD) between the predicted and calculated values of 0.04%, 0.7%, and 0.01%, respectively. The viscosity data were represented as a function of temperature and composition via Vogel–Tamman–Fulcher (VTF) type equation at an AAD of 0.6%

  10. Validation Testing of the Nitric Acid Dissolution Step Within the K Basin Sludge Pretreatment Process

    Energy Technology Data Exchange (ETDEWEB)

    AJ Schmidt; CH Delegard; KL Silvers; PR Bredt; CD Carlson; EW Hoppe; JC Hayes; DE Rinehart; SR Gano; BM Thornton

    1999-03-24

    The work described in this report involved comprehensive bench-scale testing of nitric acid (HNO{sub 3}) dissolution of actual sludge materials from the Hanford K East (KE) Basin to confirm the baseline chemical pretreatment process. In addition, process monitoring and material balance information was collected to support the development and refinement of process flow diagrams. The testing was performed by Pacific Northwest National Laboratory (PNNL)for the US Department of Energy's Office of Spent Fuel Stabilization (EM-67) and Numatec Hanford Corporation (NHC) to assist in the development of the K Basin Sludge Pretreatment Process. The baseline chemical pretreatment process for K Basin sludge is nitric acid dissolution of all particulate material passing a 1/4-in. screen. The acid-insoluble fraction (residual solids) will be stabilized (possibly by chemical leaching/rinsing and grouting), packaged, and transferred to the Hanford Environmental Restoration Disposal Facility (ERDF). The liquid fraction is to be diluted with depleted uranium for uranium criticality safety and iron nitrate for plutonium criticality safety, and neutralized with sodium hydroxide. The liquid fraction and associated precipitates are to be stored in the Hanford Tank Waste Remediation Systems (TWRS) pending vitrification. It is expected that most of the polychlorinated biphenyls (PCBs), associated with some K Basin sludges, will remain with the residual solids for ultimate disposal to ERDF. Filtration and precipitation during the neutralization step will further remove trace quantities of PCBs within the liquid fraction. The purpose of the work discussed in this report was to examine the dissolution behavior of actual KE Basin sludge materials at baseline flowsheet conditions and validate the.dissolution process step through bench-scale testing. The progress of the dissolution was evaluated by measuring the solution electrical conductivity and concentrations of key species in the

  11. Validation Testing of the Nitric Acid Dissolution Step Within the K Basin Sludge Pretreatment Process

    International Nuclear Information System (INIS)

    The work described in this report involved comprehensive bench-scale testing of nitric acid (HNO3) dissolution of actual sludge materials from the Hanford K East (KE) Basin to confirm the baseline chemical pretreatment process. In addition, process monitoring and material balance information was collected to support the development and refinement of process flow diagrams. The testing was performed by Pacific Northwest National Laboratory (PNNL)for the US Department of Energy's Office of Spent Fuel Stabilization (EM-67) and Numatec Hanford Corporation (NHC) to assist in the development of the K Basin Sludge Pretreatment Process. The baseline chemical pretreatment process for K Basin sludge is nitric acid dissolution of all particulate material passing a 1/4-in. screen. The acid-insoluble fraction (residual solids) will be stabilized (possibly by chemical leaching/rinsing and grouting), packaged, and transferred to the Hanford Environmental Restoration Disposal Facility (ERDF). The liquid fraction is to be diluted with depleted uranium for uranium criticality safety and iron nitrate for plutonium criticality safety, and neutralized with sodium hydroxide. The liquid fraction and associated precipitates are to be stored in the Hanford Tank Waste Remediation Systems (TWRS) pending vitrification. It is expected that most of the polychlorinated biphenyls (PCBs), associated with some K Basin sludges, will remain with the residual solids for ultimate disposal to ERDF. Filtration and precipitation during the neutralization step will further remove trace quantities of PCBs within the liquid fraction. The purpose of the work discussed in this report was to examine the dissolution behavior of actual KE Basin sludge materials at baseline flowsheet conditions and validate the.dissolution process step through bench-scale testing. The progress of the dissolution was evaluated by measuring the solution electrical conductivity and concentrations of key species in the dissolver

  12. Adsorption of Carboxylic Acids on Reservoir Minerals from Organic and Aqueous Phase

    DEFF Research Database (Denmark)

    Madsen, Lene; Lind, Ida

    1998-01-01

    Adsorption of organic acids onto North Sea chalk and pure minerals from a hydrocarbon phase and an aqueous phase show that the maximum adsorption is larger for calcite than for silicate surfaces in the hydrocarbon phase. The opposite is observed, however, in the aqueous phase. This suggests that...

  13. Processing of LEU targets for 99Mo production -- Dissolution of metal foils by nitric-acid/sulfuric-acid mixtures

    International Nuclear Information System (INIS)

    The first step in processing low-enriched uranium (LEU) targets for production of 99Mo is to dissolve the neutron-irradiated uranium foil coming from the reactor. Appropriate conditions for dissolving the foils were determined by measuring the dissolution rates for uranium foil over a wide range of temperatures and acid concentrations. On the basis of these dissolution rates, the process chemistry, and a model that integrates dissolution rates as a function of temperature and composition, a closed stainless-steel dissolver was designed, built, and tested for dissolving up to 18 g of uranium foil. The results were quite successful, with the uranium foil being dissolved within one hour as desired. To do this, the dissolver temperature must be in the range from 97 to 102 C, and the dissolver solution (cocktail) must have a composition of 3M nitric acid and 2M sulfuric acid. The final dissolver solution is subsequently processed to separate 99Mo from uranium, fission products, and other elements

  14. Processing of LEU targets for 99Mo production - Dissolution of metal foils by nitric-acid/sulfuric-acid mixtures

    International Nuclear Information System (INIS)

    The first step in processing low-enriched uranium (LEU) targets for production of 99Mo is to dissolve the neutron-irradiated uranium foil coming from the reactor. Appropriate conditions for dissolving the foils were determined by measuring the dissolution rates for uranium foil over a wide range of temperatures and acid concentrations. On the basis of these dissolution rates, the process chemistry, and a model that integrates dissolution rates as a function of temperature and composition, a closed stainless-steel dissolver was designed, built, and tested for dissolving up to 18 g of uranium foil. The results were quite successful, with the uranium foil being dissolved within one hour as desired. To do this, the dissolver temperature must be in the range from 97 to 102 deg. C, and the dissolver solution (cocktail) must have a composition of 3M nitric acid and ZM sulfuric acid. The final dissolver solution is subsequently processed to separate 99Mo from uranium, fission products, and other elements. (author)

  15. Material compatibility evaluataion for DWPF nitric-glycolic acid - literature review

    International Nuclear Information System (INIS)

    Glycolic acid is being evaluated as an alternative for formic and nitric acid in the DWPF flowsheet. Demonstration testing and modeling for this new flowsheet has shown that glycolic acid and glycolate has a potential to remain in certain streams generated during the production of the nuclear waste glass. A literature review was conducted to assess the impact of glycolic acid on the corrosion of the materials of construction for the DWPF facility as well as facilities downstream which may have residual glycolic acid and glycolates present. The literature data was limited to solutions containing principally glycolic acid. The reported corrosion rates and degradation characteristics have shown the following for the materials of construction: For C276 alloy, the primary material of construction for the CPC vessels, corrosion rates of either 2 or 20 mpy were reported up to a temperature of 93 deg C; For the austenitic stainless steels, 304L and 316L, variable rates were reported over a range of temperatures, varying from 2 mpy up to 200 mpy (at 100 deg C); For 690, G30, Allcorr, Ultimet and Stellite alloys no data were available; and, For relevant polymers where data are available, the data suggests that exposure to glycolic acid is not detrimental. The literature data had limited application to the DWPF process since only the storage and feed vessels, pumps and piping used to handle the glycolic acid are directly covered by the available data. These components are either 304L or 316L alloys for which the literature data is inconsistent (See Bullet 2 above). Corrosion rates in pure glycolic acid solutions also are not representative of the DWPF process streams. This stream is complex and contains aggressive species, i.e. chlorides, sulfates, mercury, as well as antifoaming agents which cumulatively have an unknown effect on the corrosion rates of the materials of construction. Therefore, testing is recommended to investigate any synergistic effects of the aggressive

  16. Effect of aqueous extract of Origanum vulgare and Melilotus officinalis onproduction of nitric oxide (NO in cultured vascular endothelial cells (mouse endothelioma F-2 cell line

    Directory of Open Access Journals (Sweden)

    M.Ansari

    2006-01-01

    Full Text Available Background and purpose: During recent years, nitric oxide (NO has been considered as a molecule involved in migraine headaches. This free radical involves in initiation of migraine headaches via NO/cGMP signaling pathway and vascular relaxation specially big intracranial arteries. Therefore, we studied the effects of aqueous extract of Origanum vulgare and Melilotus officinalis prescribed in migraine treatment in traditional & modern medicine, on NO level in cultured endothelial cells.Materials and Methods: Each crude herb (25g was mixed with 200 ml distilled water. End extract obtained after filtering and drying. Endothelial cells propagated in DMEM medium containing 10% FCS and 1-2% penicillin-streptomycin. The nitrite concentration was measured as an indicator of nitric oxide production according to the Griess reaction and with ELISA in 540 nm.Results: Concentrations of 100, 200 and 400 g/ml of Origanum vulgare, reduced NO levels compared with control to 13.1 % (p<0.05, 25.8% (p<0.01 and 33.9% (p<0.001 respectively. However, despite our expectation melilotus officinalis increased NO level. The concentrations of 100, 200 and 400 g/ml of the herb, increased NO levels to 12.7 (p<0.05, 36.5% (p<0.001 & 72.9% (p<0.001 respectively.Conclusion: We concluded that aqueous extract of Origanum vulgare probably decreases migraine headaches by reducing NO and aqueous extract of Melilotus officinalis does not act through this mechanism.

  17. Oxidative aromatization of Hantzsch 1,4-dihydropyridines by aqueous hydrogen peroxide-acetic acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A simple method for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is achieved by using hydrogen peroxide as green oxidant and acetic acid as catalyst in aqueous solution.

  18. High pressure Raman spectroscopic study of the effects of n-ethylamines and water on the 2-nitropropane/Nitric acid system

    Energy Technology Data Exchange (ETDEWEB)

    Gobin, Cedric; Petitet, Jean Pierre [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions, CNRS, Institut Galilee, Universite Paris XIII, 99 av. J-B Clement, 93430 Villetaneuse (France)

    2005-12-01

    High pressure Raman spectroscopy measurements in a diamond anvil cell (0-10 GPa) on 2-nitropropane/nitric acid/X (X=triethylamine, diethylamine, and water) ternary systems and 2-nitropropane/nitric acid/water/Y (Y=triethylamine and diethylamine) quaternary systems are reported. The modifications of the chemical behavior of the 2-nitropropane/nitric acid model system, induced by the presence of triethylamine, diethylamine, and/or water, were studied at ambient and high pressure. At ambient pressure, the ionization of the nitric acid has been observed with each of the additives. Moreover, in the case of ethylamines, new peaks have been observed and the hypothesis of a 2-nitropropane/ethylamine complex is advanced. At high pressure, the decomposition of the 2-nitropropane/nitric acid system, with an oxygen balance near zero, has been observed only in presence of triethylamine. The role of each additive to the 2-nitropropane/nitric acid system in the modification of the respective reducing and oxidizing character of the components, and in the reactivity of the system, is discussed. Several hypotheses are advanced concerning the sensitizing effect of the additives on the 2-nitropropane/nitric acid system. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  19. 利用硝酸回收机械化学活化后的硫化物浓缩液中的铅%Recovery of Lead from Sulfide Concentrate after Mechanochemical Activation Using Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    A.G. Kholmogorov; O.N. Kononova; G.L. Pashkov; L.V. Shashina; V.P. Plekhanov; A.A. Sabetskiy

    2005-01-01

    Decomposition of lead sulfide concentrates in nitric acidic solutions after ferric (Ⅲ) nitrate addition and mechanical preparation has been investigated. It was found out that the decomposition can be achieved in of mechanochemical activation. The use of [Fe(NO3)3-HNO3-H2O] aqueous salt system allows the decomposition of lead sulfide concentrate at room temperature and in this case the concentration of HNO3 does not exceed mechanochemical activation of this concentrate. The insoluble residues after the leaching contain SiO2, S0, FeCO3 and PbSO4.

  20. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    Directory of Open Access Journals (Sweden)

    M. Ammann

    2008-09-01

    Full Text Available Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3, an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g. The uptake coefficient was reduced by a factor of 5–50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15, which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12 and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  1. Succinic acid in aqueous solution : connecting microscopic surface composition and macroscopic surface tension

    OpenAIRE

    Werner, Josephina; Julin, Jan; Dalirian, Maryam; Prisle, Nønne; Öhrwall, Gunnar; Persson, Ingmar; Björneholm, Olle; Riipinen, Ilona

    2014-01-01

    The water vapor interface of aqueous solutions of succinic acid, where pH values and bulk concentrations were varied, has been studied using surface sensitive X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations. It was found that succinic acid has a considerably higher propensity to reside in the aqueous surface region than its deprotonated form, which is effectively depleted from the surface due to the two strongly hydrated carboxylate groups. From both XPS experim...

  2. Radiation-induced destruction peculiarities of hydroxyl containing amino acids in diluted aqueous solution

    International Nuclear Information System (INIS)

    Amino acids aqueous solution of alpha-alanine and beta-alanine, serine, threonine (concentration 5*10-4 M) were irradiated with dose rate 0.35 Gy/s in range 100-1100 Gy and analysed. Effectiveness of radiation-induced decomposition process depends on row of factors: concentration of amino acid aqueous solution, pH, oxygen presence and other acceptors

  3. Electrolytic destruction of nitric acid in various reprocessing streams of fast breeder reactor fuels

    International Nuclear Information System (INIS)

    The salting concentration of Nitric acid to Reprocessing Plants of FBR fuels is 4 M HNO3,. Adjustment of the free acidity of the Dissolver solution from 8 to 10 M HNO3, to a concentration of 4M HNO3 is done cathodically. This would increase the throughput of the plant. The concentration of HNO3 in first cycle raffinate, HAW, that would be stored in SS tanks (interim storage before vitrification) should be less than 6 M; otherwise severe corrosion problems would occur. The HAW discharged in FBR fuel reprocessing plants would contain around 4M HNO3. This has to be reduced to around 0.4M HNO3 in order to effect efficient reduction in waste volume, by evaporation. This has been achieved in the catalytic reduction of HNO3 to oxides of nitrogen. Current efficiency in the 1 L level is around 46%. Conventionally, HNO3 in raffinates are destroyed by addition of formaldehyde. The disadvantages of this method are highlighted in this paper. Addition of 0.01 M Cu2+ is found to completely avoid critical concentration of HNO3 below which nitrate ions will not be destroyed; instead H2 gas would be evolved. The results of these experiments in a simulated HAW are also included in this paper. Operation and the results of electrolytic destruction of HNO3 in simulated raffinate in a scaled-up SS equipment of 3.5 L capacity are also described in this payer. (author)

  4. Photolysis of Nitric Acid and Nitrate on Natural and Artificial Surfaces.

    Science.gov (United States)

    Ye, Chunxiang; Gao, Honglian; Zhang, Ning; Zhou, Xianliang

    2016-04-01

    Photolysis of nitric acid and nitrate (HNO3/nitrate) was investigated on the surfaces of natural and artificial materials, including plant leaves, metal sheets, and construction materials. The surfaces were conditioned in the outdoor air prior to experiments to receive natural depositions of ambient HNO3/nitrate and other atmospheric constituents. The photolysis rate constant (JHNO3(s)) of the surface HNO3/nitrate was measured based on the production rates of nitrous acid (HONO) and nitrogen oxides (NOx). The JHNO3(s) values, from 6.0 × 10(-6) s(-1) to 3.7 × 10(-4) s(-1), are 1 to 3 orders of magnitude higher than that of gaseous HNO3. The HONO was the major product from photolysis of HNO3/nitrate on most plant leaves, whereas NOx was the major product on most artificial surfaces. The JHNO3(s) values decreased with HNO3/nitrate surface density and could be described by a simple analytical equation. Within a typical range of HNO3/nitrate surface density in the low-NOx forested areas, photolysis of HNO3/nitrate on the forest canopy can be a significant source for HONO and NOx for the overlying atmosphere. PMID:26936001

  5. A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2003-05-01

    Full Text Available In situ Fourier transform infrared (FTIR extinction spectra of supercooled H2SO4/H2O and HNO3/H2O solution droplets were recorded in the large coolable aerosol chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere of Forschungszentrum Karlsruhe for a range of aerosol compositions and at temperatures extending down to 192 K. The measured spectra were quantitatively analysed in terms of aerosol composition and mass concentration by using Mie theory in combination with published refractive index data as input parameters. Simultaneously, total sulphuric acid and nitric acid mass concentrations from filter analysis and total water concentrations measured with the Lyman-a hygrometer of Forschungszentrum Jülich were used to calculate the aerosol composition at thermodynamic equilibrium inside the aerosol chamber. By comparing these measured aerosol parameters with those retrieved from the analysis of the FTIR spectra, the accuracy of the literature data sets of refractive indices could be assessed. In summary, four data sets were tested in the H2SO4/H2O system as well as two data sets in the HNO3/H2O system, partly revealing significant discrepancies in the retrieved aerosol properties. Potential explanations for these differences are discussed in this paper.

  6. A safer and flexible method for the oxygen functionalization of carbon nanotubes by nitric acid vapors

    Energy Technology Data Exchange (ETDEWEB)

    Santangelo, Saveria, E-mail: saveria.santangelo@unirc.it [Dipartimento di Ingegneria Civile, dell’Energia, dell’Ambiente e dei Materiali (DICEAM), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Piperopoulos, Elpida [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Fazio, Enza [Dipartimento di Fisica e di Scienze della Terra (DFST), Università di Messina, 98166 Messina (Italy); Faggio, Giuliana [Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Ansari, Shabana [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Lanza, Maurizio [Istituto per i Processi Chimico Fisici (IPCF) del CNR, 98158 Messina (Italy); Neri, Fortunato [Dipartimento di Fisica e di Scienze della Terra (DFST), Università di Messina, 98166 Messina (Italy); Messina, Giacomo [Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Milone, Candida [Dipartimento di Ingegneria Eletronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy)

    2014-06-01

    The functionalization by nitric acid vapors at azeotropic concentration has been recently proposed to eliminate drawbacks of the widely utilized liquid phase functionalization method. This work suggests to exploit the so-called “salt effect” to improve the vapor phase oxidation method in terms of safety and flexibility. Increasing the relative volatility of acid, the addition of Mg(NO{sub 3}){sub 2} salt to the HNO{sub 3} + H{sub 2}O solution allows (i) obtaining vapors with HNO{sub 3} at the azeotropic concentration from a more diluted liquid solution (i.e. operating under safer conditions), and (ii) varying the concentration of HNO{sub 3} in the vapor phase even above the azeotropic concentration limit (with improved process flexibility). High-resolution transmission electron microscopy, thermo-gravimetry, Raman spectroscopy and X-ray photoemission spectroscopy systematic analyses are carried out on pristine and oxidized nanotubes in order to assess their functionalization degree, surface chemistry and structural evolution. The most relevant finding of this preliminary study is that the nanotube functionalization extent increases linearly with the HNO{sub 3} vapor concentration.

  7. Inducible nitric oxide synthase links NF-κB to PGE2 in polyunsaturated fatty acid altered fibroblast in-vitro wound healing

    OpenAIRE

    Turek John J; Jia Yi

    2005-01-01

    Abstract Background This study investigated mechanisms of altered fibroblast collagen production induced by polyunsaturated fatty acids. 3T3-Swiss fibroblasts were grown in medium containing either eicosapentaenoic or arachidonic acid. The effects of nuclear factor-kappaB activation by lipopolysaccharide on inducible nitric oxide synthase, nitric oxide, prostaglandin E2, collagen production, and in-vitro wound healing were studied. Results Eicosapentaenoic acid treated cells produced less pro...

  8. Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

    Science.gov (United States)

    Iraci, Laura T.; Michelsen, Rebecca R.; Ashbourn, Samatha F. M.; Rammer, Thomas A.; Golden, David M.

    2005-01-01

    Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

  9. Task-specific ionic liquids incorporating alkyl phosphate cations for extraction of U(VI) from nitric acid medium. Synthesis, characterization, and extraction performance

    International Nuclear Information System (INIS)

    Imidazole-based task-specific ionic liquids designed to extract U(VI) from nitric acid medium were synthesized through the introduction of tributyl phosphate functional group in cationic of these ionic liquids. Their structures were confirmed by Fourier transform infrared spectrometer, nuclear magnetic resonance spectrum and element analysis. These task-specific ionic liquids can be used simultaneously as solvents and extractants for extracting U(VI) in nitric acid medium. Preliminary extraction data showed that they could be efficiently used to extract U(VI) in nitric acid medium at room temperature. (author)

  10. Interaction of ferroceneboronic acid with diols at aqueous and non-aqueous conditions - signalling and binding abilities of an electrochemical probe for saccharides

    International Nuclear Information System (INIS)

    Highlights: • Electrochemical characterisation of ferroceneboronic acid-diol interactions in non-aqueous solutions. • Elucidation of the signalling process and signalling mechanism of the ferroceneboronic acid upon interaction with diols in aqueous and non-aqueous solutions. • Effect of coordination of boron atom on electrochemistry of ferroceneboronic acid in free and bound forms with diols. - Abstract: Ferroceneboronic acid (FcBA) was employed as a model compound for clarification of binding and signalling properties of molecular probe for saccharides. As the simplest electrochemically active boronic acid, its interactions with diverse diols were studied in homogeneous phase under aqueous and non-aqueous conditions. The FcBA-diol system was examined by cyclic voltammetry resulting in two redox pairs corresponding to free and bound forms of FcBA. Redox potential of the bound form of FcBA was shifted in the cathodic direction in aqueous conditions due to coordination of the hydroxyl group to the boron atom. Oppositely, the anodic shift of the redox potential was observed upon the interaction of FcBA with diols in non-aqueous solvents. The binding properties and signalling mechanism of electrochemically active boronic acids were deduced and the assumptions resulting from the electrochemical behaviour were confirmed by 1H and 11B NMR spectroscopies. The binding constants of the tested diols in aqueous and non-aqueous media were determined and compared

  11. Bis(2-ethylhexyl)diglycolamic acid for the mutual separation of Europium (III) and Americium (III) from citric acid - nitric acid medium

    International Nuclear Information System (INIS)

    High-level liquid waste arises from fast reactor fuel reprocessing contains significant quantities of lanthanides and trivalent minor actinides. Recently, the partitioning of minor actinides from fast reactor-high active waste (FR-HAW) using a TRUEX solvent, composed of a solution of 0.2 M octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO)-1.2 M tri-n-butylphosphate (TBP) in n-dodecane is demonstrated. A new stripping formulation composed of a solution of 0.1 M citric acid in 0.1 M nitric acid was employed for back extraction of trivalents from the loaded TRUEX solvent. Thus the mutual separation lanthanides and actinides requires a suitable extractant for separating them from citric acid medium

  12. Effect of ascorbic acid supplementation on nitric oxide metabolites and systolic blood pressure in rats exposed to lead

    Directory of Open Access Journals (Sweden)

    Mohammad Amani

    2010-01-01

    Full Text Available Background: Extended exposure to low levels of lead causes high blood pressure in human and laboratory animals. The mechanism is not completely recognized, but it is relatively implicated with generation of free radicals, oxidant agents such as ROS, and decrease of available nitric oxide (NO. In this study, we have demonstrated the effect of ascorbic acid as an antioxidant on nitric oxide metabolites and systolic blood pressure in rats exposed to low levels of lead. Materials and Methods: The adult male Wistar rats weighing 200-250 g were divided into four groups: control, lead acetate (receiving 100 ppm lead acetate in drinking water, lead acetate plus ascorbic acid (receiving 100 ppm lead acetate and 1 g/l ascorbic acid in drinking water, and ascorbic acid (receiving 1 g/l ascorbic acid in drinking water groups. The animals were anesthetized with ketamin/xylazine (50 and 7 mg/kg, respectively, ip and systolic blood pressure was then measured from the tail of the animals by a sphygmomanometer. Nitric oxide levels in serum were measured indirectly by evaluation of its stable metabolites (total nitrite and nitrate (NOc. Results: After 8 and 12 weeks, systolic blood pressure in the lead acetate group was significantly elevated compared to the control group. Ascorbic acid supplementation could prevent the systolic blood pressure rise in the lead acetate plus ascorbic acid group and there was no significant difference relative to the control group. The serum NOc levels in lead acetate group significantly decreased in relation to the control group, but this reduction was not significantly different between the lead acetate plus ascorbic acid group and the control group. Conclusion: Results of this study suggest that ascorbic acid as an antioxidant prevents the lead induced hypertension. This effect may be mediated by inhibition of NOc oxidation and thereby increasing availability of NO.

  13. Model nitride irradiated nuclear fuel: production, reaction with water and dilution in nitric acid

    International Nuclear Information System (INIS)

    Samples of the model nuclear fuel (MNF) were made from separately synthesized nitride powders uranium-plutonium, zirconium, lanthanum and metal additives of simulators (Mo, Pd, Rh, Ag) fission products. Synthesis of initial nitride components was carried out from individual oxides, using a carbo-thermal restoration method. From MNF samples baked at a temperature of 1750 C. degrees, were made ceramographic specimens which were investigated by a scanning electron microscope. The analysis showed that distribution of the MNF components and structure of the samples corresponds to distribution of these components in the irradiated nitride fuel. The samples of MNF of nitride fuel were used for carrying out researches on dissolution in water and nitric acid. Experiments on studying the interaction of MNF with water have been made at 20, 50 and 80 C. degrees. The speed of leaching has been determined by a way of measuring the activity of water (Bq/l) in time. It is shown that an increase of temperature leads to an increase of the speed of leaching of plutonium. The formation of a precipitation, allegedly polymeric forms of plutonium, has been observed. The estimated speed of leaching of plutonium from MNF in water at 80 C. degrees is -0,0064 μgPu/(mm2*h). From elements of FP simulators, molybdenum appears to be the most significantly leached. The dissolution of MNF in nitric acid (7,8 and 9,4 mol/l) has been carried out at boiling temperature (106-109 C. degrees). During the process of dissolution, gases were emitted. The assessment of composition of the emitted gases has been carried out. During the filtering of the solutions a precipitate whose weight makes about 2% from the weight of initial fuel has been found. Precipitate represents small powder of metal with gray color. Precipitate was investigated by a scanning electron microscope. The analysis of ranges of absorption of solution showed that the Pu(VI) share to the general content of plutonium in solution can reach

  14. Amides as phase modifiers for N,N'-tetraalkylmalonamide extraction of actinides and lanthanides from nitric acid solutions

    International Nuclear Information System (INIS)

    The N,N'-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) separations under high nitric acid conditions. There are several issues that challenge the further development of these ligands. One is the development of improved synthetic procedures that lend themselves to commercial scale-up. Another major issue is the third-phase formation that occurs when the N,N'-tetraalkylmalonamides are contacted with medium-to-high nitric acid concentrations in hydrocarbon solvents. To address the synthesis issue, the authors have developed a new synthetic approach for preparing these materials. Third-phase formation can be eliminated by addition of diluent modifiers such as tributylphosphate (TBP). TBP is inappropriate if a nonphosphate-containing process stream is required. Amides have been proposed as alternatives for TBP in a variety of applications because of their ease of synthesis and the variety of substituents that can be generated. The authors have been able to develop an amide phase-modified system that extends the working process range of alkylinalonamides (0.5 M) in dodecane: from 3.5 M to 7.5 M nitric acid and in Isopar H (branched hydrocarbon) from 4.0 M to 10.0 M nitric acid using 1.0 M di-2-ethylhexylacetamide/0.5 M alkylmalonamide. The Kd values were comparable to extraction with alkylinalonamide in Isopar H or hydrogenated tetrapropylene (TPH) solvents. The overall extraction system was more robust than the phase-uninodified system allowing for greater temperature and acid concentration fluctuations without third-phase formation

  15. The effect of gamma irradiation on the nitric acid solution as washing agent used in Ru-U extraction process

    International Nuclear Information System (INIS)

    The continuous extraction of uranium was carried out in a 12 -stage bank of mixer-settlers using a 30% volume Tbp-kerosene mixture solvent. The uranyl nitrate solution of 200 g U/l containing 11 mg/l of ruthenium as impurity was fed to the mixer settlers at 7th stage at 75 ml/h flow rate. The 30% volume Tbp-kerosene solvent was introduced at 1st stage at 150 ml/h flow rate, while the nitric acid washing solution already gamma irradiated at 103, 105, 107, 108 rads respectively was fed at 12th stage at 56 ml/h flow rate. Extraction time was 6 hours, and the stirring was done at 2300 rpm. The experiments showed that gamma irradiation caused the degradation of nitric acid which was shown by the decrease in its acidity. Increasing radiation dose to the nitric acid solution resulted in the decrease of uranium recovery and the FDRu-U. At the lowest radiation dose (i.e. 103 rad) the uranium recovery and FDRu-U obtained respectively were found to be 96.37% and 2.19, while that at the highest radiation dose (i.e. 108 rad) they were 88.20% and 2.01 respectively

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

    International Nuclear Information System (INIS)

    Reactions of H, OH, eaq- 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 eaq- with these compounds were of the order of 109dm3mol-1s-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 (>1010dm3mol-1s-1) while O- radical anions could oxidize these molecules to give phenoxyl type of radicals. Amongst the one-electron oxidants, only N3 radicals and SO4- radicals could oxidize salicylic acid while 5-sulpho-salicylic acid could be oxidized only by SO4- radicals indicating that while one-electron reduction potential for semi-oxidized SA may beo1 for N3? radical), it is more than 1.33V vs. NHE for semi-oxidized SSA species

  17. Study of the nitric acid influence on the production of Ce O2 with high specific surface area

    International Nuclear Information System (INIS)

    The cerium oxide (Ce O2) main characteristics for use as catalyst in an exhaust gases purification system are: high specific surface area (approximately 30 m2/g after calcination at 800 deg C/ 2 hs), and thermal stability. The Ce O2 powders obtained by conventional route, i.e., precipitation, and submitted high temperature (800 deg C) heat treatments, showed low specific surface area. In this work nitric acid effects on the Ce O2 surface area values were investigated. The variables studied were nitric acid concentration, humidity content in the raw material, re pulp after leaching, addition of hydrogen peroxide (H2 O2) and starting material specific surface area. By this process, it was possible to obtain powders with specific surface area larger than 40 m2/g, after treatment at 800 deg C during two hours. (author)

  18. Effect of nitric acid leaching on the separation of U and common impurities from solid (U, Pu, Ag) analytical waste

    International Nuclear Information System (INIS)

    The effect of leaching a solid analytical waste of (U,Pu)O2 and AgCl with concentrated nitric acid for different time intervals was studied. The amount of Pu/U leached was found to be nearly same in the selected time interval 15-90 minutes. Hence the effect of multi-step leaching on the dissolution of U/Pu was studied. After four steps of 15 minute leaching, entire uranium was leached along with about 3% Pu. Later keeping the time constant, the effect of nitric acid molarity on the leaching of U and Pu was investigated. The leaching of impurities was found to decrease with each step. However the amounts of rare earths and Ag leached were found to be negligible. (author)

  19. (U, Th, RE) hydroxide dissolution of Bangka's monazite base decomposition, using nitric acid

    International Nuclear Information System (INIS)

    The (U, Th, RE) hydroxide dissolution experiment on Bangka's monazite base decomposition product using nitric acid (HNO3) reagent has been done. The uses of HNO3 for (U, Th, RE)NO3 solution product can do extraction with TBP-Kerosene to take impurity of Th in the end product of RE. The solution use of HCl gave end product RE with high Th as 1000 - 1500 ppm. The aim of the experiment was to find a good conditions of dissolution with applied parameter were HNO3 normality, amount of redactor, temperature and dissolution time respectively. This experiment used feed (U, Th, RE) hydroxide as product -200 mesh Bangka monazite base decomposition. The amount of feed for a time experiment is 50 gram wet, 36% of water content, the compartment volume of reagent / weight of feed is 1. The results gave a good experiment conditions i.e. HNO3 14 N, amount of redactor 20 ml H2O2, at room temperature and a hour dissolution time respectively. Such conditions gave the recovery of U 53.14 %; Th 88.98 %; RE2O3 70.03% and P2O5 53.89 %

  20. Dissolution of plutonium dioxide in nitric acid media by silver(II) electroreduction

    International Nuclear Information System (INIS)

    Oxidative dissolution of plutonium dioxide with electrogenerated silver(II) was undertaken first on an analytical scale in order to discover the parameters controlling this dissolution process and to prove the feasibility of the technique for 300 grams of material. The influence on the rate of PuO2 dissolution of the following parameters was studied: mass of PuO2, current density, total concentration of silver ion, nitric acid concentration, temperature, and agitation efficiency. The results demonstrate that: 1. the limiting step of the dissolution process is the electrogeneration of silver(II); 2. the dissolution of PuO2 can be achieved with a good current efficiency; 3. the best temperature range is 30±100C; 4. the optimum [HNO3] is 4 to 6 M; 5. the plutonium(VI) solution up to 500 g l-1 can be prepared. A six litres capacity thermostated glass electrolyser was built which consists of two separated compartments inlcuding: 1. an anodic compartment equipped with a cylindrical platinum grid electrode (area, 1000 cm2) and a tantalum propeller, and 2. a cathodic compartment of 0.2 litre capacity consisting of an aluminium silicate diaphragm with a tantalum rod cathode. Quantitative dissolutions of 300 g of PuO2 in 4 M HNO3 were performed for 2 h at an applied current of 60 A. (orig.)

  1. Evaluation of anion exchange resins for plutonium-uranium separations in nitric acid

    International Nuclear Information System (INIS)

    Pellicular, macroreticular and microreticular (gel type) anion exchange resins were compared for separation of plutonium from nitric acid solutions of mixed plutonium-uranium. All the macroreticular resins were 20 to 50 mesh beads. Dowex 1-X4 gel resin was 50 to 80 mesh beads. The resins were held in glass columns with coarse glass frits at the bottom of the columns. The top of the columns contained 50 ml reservoirs. The flow rates were controlled at 4 cm3.min-1.cm-2. One-centimeter bore columns with 15-cm resin bed heights were used for the plutonium elution and breakthrough capacity experiments, whereas 1.7 cm bore columns with 20 cm bed heights were used for the uranium washing experiments. As Pellionex SAX (pellicular resin) and Amberlite IRA-93 (weak base macroreticular anion exchange resin) were found to have better uranium washing and plutonium eluating characteristics than any of the resins tested. However, the capacity of the pellicular resin was much lower than that of the other resins. (T.G.)

  2. Investigations of the inhibition of copper corrosion in nitric acid solutions by ketene dithioacetal derivatives

    Science.gov (United States)

    Fiala, A.; Chibani, A.; Darchen, A.; Boulkamh, A.; Djebbar, K.

    2007-10-01

    Ketene dithioacetal derivatives, namely 3-[bis(methylthio)methylene] pentane-2,4-dione ( 1), 3-(1,3-dithian-2-ylidene) pentane-2,4-dione ( 2) and 3-(1,3-dithiolan-2-ylidene) pentane-2,4-dione ( 3) were synthesized and their respective capacity to inhibit copper corrosion in 3 M HNO 3 was investigated by means of weight loss, potentiodynamic polarization, scanning electron microscopy (SEM) and energy dispersive X-ray fluorescence (XRF). The obtained results indicate that the addition of these compounds significantly decreases the corrosion rate. Potentiodynamic polarization studies clearly showed that the inhibition efficiency increases with increasing concentration of the investigated compounds at a fixed temperature, but decreases with increasing temperature. These results on the whole showed that the studied substances are good cathodic inhibitors for copper corrosion in nitric acid medium. SEM and energy dispersive X-ray (EDAX) examination of the copper surface revealed that these compounds prevented copper from corrosion by adsorption on its surface to form a protective film, which acts as a barrier to aggressive agents. The presence of these organic compounds adsorbed on the electrode surface was confirmed by XRF investigations.

  3. Uranium removal from nitric acid raffinate solution by solvent immobilized PVC cement

    International Nuclear Information System (INIS)

    The present work deals with uranium removal from a nitric acid raffinate (waste) solution using prepared solvent (tri-butyl phosphate, TBP) immobilizing PVC cement (SIC) as a suitable adsorbent. The studied relevant factors affecting uranium adsorption onto SIC adsorbent involved; contact time, solution molarity, initial uranium concentration and temperature. The obtained adsorption isotherm of uranium onto the SIC adsorbent was fitted to Langmuir, Freundlich and Dubinin-Radushkeviech (D-R) adsorption models. The results showed that the obtained equilibrium data fitted well the Langmuir isotherm. Additionally, it was found that the adsorption process obeys the pseudo second-order kinetic model. On the other hand, the calculated theoretical capacity of our prepared SIC adsorbent reached about 17 g U/kg SIC. Uranium adsorption from the studied raffinate solution was carried out applying the attained optimum conditions. The obtained data showed that 58.4 mg U/5 g SIC were adsorbed. However, using of 2 M HNO3 solution as an eluent, 93 (54.3 mg U) from the adsorbed amount were eluted. (author)

  4. The inhibited effect of some tetrazolic compounds towards the corrosion of brass in nitric acid solution

    International Nuclear Information System (INIS)

    The effect of the addition of some tetrazolic type organic compounds: 1-phenyl-5-mercapto-1,2,3,4-tetrazole (PMT), 1,2,3,4-tetrazole (TTZ), 5-amino-1,2,3,4-tetrazole (AT) and 1-phenyl-1,2,3,4-tetrazole (PT) on the corrosion of brass in nitric acid is studied by weight loss, polarisation and electrochemical impedance spectroscopy (EIS) measurements. The explored methods gave almost similar results. Results obtained reveal that PMT is the best inhibitor and the inhibition efficiency (E%) follows the sequence: PMT > PT > AT > TTZ. Polarization measurements also indicated that tetrazoles acted as mixed-type inhibitors without changing the mechanism of the hydrogen evolution reaction. Partial π-charge on atoms has been calculated. Correlation between the highest occupied molecular orbital energy E HOMO and inhibition efficiencies was sought. The adsorption of PMT on the brass surface followed the Langmuir isotherm. Effect of temperature is also studied in the (25-50 deg. C) range

  5. The inhibited effect of some tetrazolic compounds towards the corrosion of brass in nitric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Mihit, M. [Laboratoire de Chimie-Physique, Equipe de Chimie Moleculaire and Corrosion, Faculte des Sciences, Agadir B.P 8106 (Morocco); El Issami, S. [Laboratoire de Chimie-Physique, Equipe de Chimie Moleculaire and Corrosion, Faculte des Sciences, Agadir B.P 8106 (Morocco); Bouklah, M. [Laboratoire de Chimie des Eaux and Corrosion, Faculte des Sciences, Oujda (Morocco); Bazzi, L. [Laboratoire de Chimie-Physique, Equipe de Chimie Moleculaire and Corrosion, Faculte des Sciences, Agadir B.P 8106 (Morocco); Hammouti, B. [Laboratoire de Chimie des Eaux and Corrosion, Faculte des Sciences, Oujda (Morocco)]. E-mail: hammoutib@yahoo.fr; Ait Addi, E. [Laboratoire de Chimie-Physique, Equipe de Chimie Moleculaire and Corrosion, Faculte des Sciences, Agadir B.P 8106 (Morocco); Salghi, R. [Laboratoire de l' Environnement et Science de l' Eau, Ecole Nationale des Sciences Appliquees d' Agadir, B.P. 33/S, Agadir (Morocco); Kertit, S. [Laboratoire de Physico-Chimie des Materiaux, Ecole Normale Superieure-Takaddoum, Rabat (Morocco)

    2006-01-15

    The effect of the addition of some tetrazolic type organic compounds: 1-phenyl-5-mercapto-1,2,3,4-tetrazole (PMT), 1,2,3,4-tetrazole (TTZ), 5-amino-1,2,3,4-tetrazole (AT) and 1-phenyl-1,2,3,4-tetrazole (PT) on the corrosion of brass in nitric acid is studied by weight loss, polarisation and electrochemical impedance spectroscopy (EIS) measurements. The explored methods gave almost similar results. Results obtained reveal that PMT is the best inhibitor and the inhibition efficiency (E%) follows the sequence: PMT > PT > AT > TTZ. Polarization measurements also indicated that tetrazoles acted as mixed-type inhibitors without changing the mechanism of the hydrogen evolution reaction. Partial {pi}-charge on atoms has been calculated. Correlation between the highest occupied molecular orbital energy E {sub HOMO} and inhibition efficiencies was sought. The adsorption of PMT on the brass surface followed the Langmuir isotherm. Effect of temperature is also studied in the (25-50 deg. C) range.

  6. Characteristic of wet method of phosphorus recovery from polish sewage sludge ash with nitric acid

    Directory of Open Access Journals (Sweden)

    Gorazda Katarzyna

    2016-12-01

    Full Text Available Sewage Sludge Ash (SSA is a concentrated source of phosphorus and can be successfully recycled via a number of different routes. This paper presents research results on phosphorus recovery from differently combusted sewage sludge with the use of nitric acid extraction. Different SSA forms from Polish thermal utilization stations were compared. It was revealed that sewage treatment technology as well as combustion technology influence many physical and chemical parameters of ashes that are crucial for further phosphorus recovery from such waste according to the proposed method. Presented research defines extraction efficiency, characterized extracts composition and verifies the possibility of using SSA as cheaper and alternative sources of phosphorus compounds. Gdynia, Kielce and Kraków SSA have the best properties for the proposed technology of phosphorus recovery with high extraction efficiency greater than 86%. Unsuitable results were obtained for Bydgoszcz, Szczecin Slag and Warszawa SSA. Extraction process for Łódź and Szczecin Dust SSA need to be improved for a higher phosphorus extraction efficiency greater than 80%.

  7. Silver ion catalyzed cerium(IV) mediated electrochemical oxidation of phenol in nitric acid medium

    International Nuclear Information System (INIS)

    Mediated electrochemical oxidation (MEO) is one of the sustainable processes for organic pollutant destruction and has been employed for organic mineralization reactions by many researchers. In the MEO a metal ion capable of exhibiting redox behavior is oxidized from lower oxidation state to higher oxidation state by an electrochemical cell and subsequently used as an oxidant for mineralizing the toxic organics into CO2 and water. The net result is the consumption of electrical energy for organic mineralization. Therefore, the current efficiency is an important factor and maximizing the current efficiency is one of the ways of reducing the running cost of the MEO process. It has been reported in the literature that the current efficiency could be increased using a metal ion catalyst having a good redox potential. In this study Ce(IV) mediated electrochemical oxidation of phenol was carried out with silver ion catalyst. The current efficiency for the electro-oxidation of cerium(III) in nitric acid was found to be increased by the addition of silver ions. This mixed mediator system was tested for the oxidation of phenol in order to optimize the parameters for organic pollutant destruction. The mineralization efficiency calculated based on the CO2 evolution was found to be higher for silver catalyzed Ce(IV) mediated oxidation compared to the non-silver catalyzed system

  8. Heterogeneous formation of polar stratospheric clouds – Part 1: Nucleation of nitric acid trihydrate (NAT

    Directory of Open Access Journals (Sweden)

    C. R. Hoyle

    2013-03-01

    Full Text Available Satellite based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarisation (CALIOP observation points. Comparing the optical properties of the modelled NAT with these observations enabled the thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM. The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed PSCs very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

  9. Heterogeneous formation of polar stratospheric clouds – Part 1: Nucleation of nitric acid trihydrate (NAT

    Directory of Open Access Journals (Sweden)

    C. R. Hoyle

    2013-09-01

    Full Text Available Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM. The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

  10. Electro-Oxidation of Concentrated Ce(Ⅲ) at Carbon Felt Anode in Nitric Acid Media

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Electro-oxidation of Ce( Ⅲ) to Ce( Ⅳ ) in parallel plate flow type electrolyzer divided with cation exchange membrane was carried out in nitric acid media at carbon felt anode under galvanostatic conditions. Carbon felt was used as an anode for its high specific surface area and high oxygen evolution overpotential. Pt coated Ti plates were used as cathcurrent efficiency (92%) until about 80% of Ce( Ⅲ) was oxidized. Then, oxygen evolution, accompanied by terminal voltage jump, took place, lowering current efficiency. Ce( Ⅲ ) was oxidized up to 90% with current efficiency of 62%. In this mode, strong carbon felt anode oxidation was observed. The wear out of carbon felt was 46% in six consequent runs (6 h of operation). After each run, carbon felt surface had to be renewed with slightly alkaline solution to remove carbon oxidation products and ensure regular operational conditions. When anode surface was blocked, oxygen evolution took place from the beginning of electrolysis due to higher actual current density. The wear out of carbon felt anode could be minimized by means of oxygen evolution prevention. In the case when electrolysis had been stopped before oxygen evolution started (at Ce( Ⅳ ) conversion of about 80% ), the wear out of anode was less than 2% during 6 consequent runs (4 h of operation).

  11. Effects of composite restorations on nitric oxide and uric acid levels in saliva

    Directory of Open Access Journals (Sweden)

    Nilgun Akgul

    2015-01-01

    Full Text Available Background and Aims: Dental materials that are used in dentistry should be harmless to oral tissues, and should, therefore, not contain any leachable toxic and diffusible substances capable of causing side effects. This study was intended to investigate the effects on salivary nitric oxide (NO and uric acid (UA levels after application of dental composite filling materials to healthy volunteers. Materials and Methods: A total of 52 individuals (32 female and 20 male participated in the study. Filtek Z250 composite filling material (3M ESPE, St Paul, MN, USA was applied to healthy volunteers. Saliva samples were collected before restoration (baseline and 1 h, 1-day, 7 days, and 30 days after restoration. NO concentrations were measured using the Griess reaction method, and UA was measured using an enzymatic method. Data were analyzed using repeated measures ANOVA and the Bonferroni post-hoc test (α =5%. Results: NO values increased statistically significant after 7 days (P 0.05. There was no correlation between NO and UA levels in saliva (P > 0.05. Conclusion: Composite resins activated the antioxidant system in saliva. However, further studies are now needed to confirm our findings and to permit a definitive conclusion.

  12. Development and performance evaluation of nano platinum coated titanium electrode for application in nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Rasmi, K.R.; Vanithakumari, S.C.; George, R.P.; Mallika, C.; Kamachi Mudali, U., E-mail: kamachi@igcar.gov.in

    2015-02-01

    Nano platinum coated titanium (NPCT) electrodes were developed using electrodeposition assisted hydrothermal method for application as electrodes in reprocessing plant under severe corrosive environment. After synthesis, the morphology of the NPCT electrode surface was characterized using Field emission scanning electron microscopy (FESEM). The phase and chemical state of the modified electrode was investigated using X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. The enhanced electrochemical activity of NPCT electrode was established by conducting hydrogen adsorption-desorption study and electrochemical oxygen reduction studies. The performance of the electrode was investigated by employing it as anode in cerium oxidation under an applied current of 0.1 A in 11.5 M nitric acid. Post performance analysis reveals the stability of the synthesized electrode. - Highlights: • Nano Pt covered Ti with higher electrochemical activity was synthesized. • Efficiency of nano Pt coated titanium was double than polycrystalline bulk Pt. • The coating was intact post experiment in very aggressive environment of HNO{sub 3}.

  13. Heterogeneous formation of polar stratospheric clouds - Part 1: Nucleation of nitric acid trihydrate (NAT)

    Science.gov (United States)

    Hoyle, C. R.; Engel, I.; Luo, B. P.; Pitts, M. C.; Poole, L. R.; Grooß, J.-U.; Peter, T.

    2013-09-01

    Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs) very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

  14. Plasma Formed in Argon, Acid Nitric and Water Used in Industrial ICP Torches

    Institute of Scientific and Technical Information of China (English)

    F. BENDJEBBAR; P. ANDRE; M. BENBAKKAR; D. ROCHETTE; S. FLAZI; D. VACHER

    2012-01-01

    Inductively coupled plasmas (ICPs) are used in spectrochemical analyses. The introduction of the sample by means of an aerosol are widely used. The introduction and the total evaporation of the aerosol is required in order to obtain a good repeatability and reproducibility of analyses. To check whether the vaporization of the aerosol droplets inside the plasma is completed, a solution could be used to compare the experimental results of the emission spectral lines with theoretical results. An accurate calculation code to obtain monatomic spectral lines intensities is therefore required, which is the purpose of the present paper. The mixtures of argon, water and nitric acid are widely used in spectrochemical analyses with ICPs. With these mixtures, we calculate the composition, thermodynamic functions and monatomic spectral lines intensities of the plasma at thermodynamic equilibrium and at atmospheric pressure. To obtain a self sufficient paper and also to allow other researchers to compare their results, all required data and a robust accurate algorithm, which is simple and easy to compute, are given.

  15. Passivity and passivity breakdown of 304L stainless steel in hot and concentrated nitric acid

    International Nuclear Information System (INIS)

    The objective of this study is to characterize the oxidation behavior of 304L stainless steel (SS) in representative conditions of spent nuclear fuel reprocessing, i.e. in hot and concentrated nitric acid. In these conditions the SS electrochemical potential is in the passive domain and its corrosion rate is low. However when the media becomes more aggressive, the potential may be shifted towards the trans-passive domain characterized with a high corrosion rate. Passivity and passivity breakdown in the trans-passive domain are of a major interest for the industry. So as to characterize these phenomenons, this work was undertaken with the following representative conditions: a 304L SS from an industrial sheet was studied, the media was hot and concentrated HNO3, long term tests were performed. First, the surface of an immersed 304L SS was characterized with several complementary techniques from the micro to the nanometer scale. Then oxidation kinetics was studied in the passive and in the trans-passive domain. The oxidation behavior was studied thanks to weight loss determination and surface analysis. Finally, oxidation evolution as a function of the potential was studied from the passive to the trans-passive domain. In particular, this allowed us to obtain the anodic curve of 304L SS in hot and concentrated and to define precisely the 304L SS limits of in such conditions. (author)

  16. A New Process Study on Comprehensive Utilization of NOx from Nitric Acid Plant

    Institute of Scientific and Technical Information of China (English)

    ZhouHou-zhen; LiangHua

    2003-01-01

    Based on studies of controlling NOx from nitric acid exhaust gas domestic and abroad, this paper has developed a new technique on removal of NOx and production of a by-product with high added value MnO2. Experiment shows, pyrolusite, whose valid composition is MnO2, of absorbing NOx has the following characteristics: quick, low cost, no secondary pollutant. Moreover, exhaust gas can attain the required standards. If the temperature of the pyrolusite serum is 30℃, pH=4, containing 90 g/L MnO2, the absorptivity for 3 000 mg/m3 NOx is 89.2%. Furthermore,few of the impurities in pyrolusite dissolve in the absorption mother solution. The purification cost of product is very low.The purity of end product MnO2 is more than 99. 995% after purifying. Therefore, it is workable for the new technique on economy and technology. There are also obvious environmental benefits and marked economic returns.

  17. Electronic spectra of plutonium ions in nitric acid and in lithium nitrate solutions

    International Nuclear Information System (INIS)

    The absorption spectra of plutonium ions in nitric acid have been described. There is a characteristic change in the absorption spectra of Pu v in lithium nitrate solutions. In 2 M-lithium nitrate a new peak at 969 nm and high absorption at 1200 nm are noticed. A decrease in the absorption by about 20% and the appearance of a new shoulder at 1120 nm in 6 M-lithium nitrate are found. There is no change in the spectrum in 4 M-lithium nitrate. The absorption spectra of plutonium ions in the spectral range 200 - 400 nm are interesting. All plutonium ions have an intense band in the region 250 - 260 nm as well as a less intense and rather diffuse band at 320 - 330 nm in lithium nitrate solutions the sharp band at 250 - 260 nm has disappeared. This suggests that this band is very sensitive to the environmental field. The band is probably produced by 5 Fq→ 5 fq-1 6 d transition as well as electron transfer. It is believed that the spectrum of Pu V at pH 6.5 represents the hydrolysis product Pu O2(O H). 9 fig., 4 tab

  18. Curcumin Derivatives as Green Corrosion Inhibitors for α-Brass in Nitric Acid Solution

    Science.gov (United States)

    Fouda, A. S.; Elattar, K. M.

    2012-11-01

    1,7- Bis-(4-hydroxy-3-methoxy-phenyl)-hepta-1,6-diene-4-arylazo-3,5-dione I-V have been investigated as corrosion inhibitors for α-brass in 2 M nitric acid solution using weight-loss and galvanostatic polarization techniques. The efficiency of the inhibitors increases with the increase in the inhibitor concentration but decreases with a rise in temperature. The conjoint effect of the curcumin derivatives and KSCN has also been studied. The apparent activation energy ( E a*) and other thermodynamic parameters for the corrosion process have also been calculated. The galvanostatic polarization data indicated that the inhibitors were of mixed-type, but the cathode is more polarized than the anode. The slopes of the cathodic and anodic Tafel lines ( b c and b a) are maintained approximately equal for various inhibitor concentrations. However, the value of the Tafel slopes increases together as inhibitor concentration increases. The adsorption of these compounds on α-brass surface has been found to obey the Frumkin's adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors.

  19. Development and performance evaluation of nano platinum coated titanium electrode for application in nitric acid medium

    International Nuclear Information System (INIS)

    Nano platinum coated titanium (NPCT) electrodes were developed using electrodeposition assisted hydrothermal method for application as electrodes in reprocessing plant under severe corrosive environment. After synthesis, the morphology of the NPCT electrode surface was characterized using Field emission scanning electron microscopy (FESEM). The phase and chemical state of the modified electrode was investigated using X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. The enhanced electrochemical activity of NPCT electrode was established by conducting hydrogen adsorption-desorption study and electrochemical oxygen reduction studies. The performance of the electrode was investigated by employing it as anode in cerium oxidation under an applied current of 0.1 A in 11.5 M nitric acid. Post performance analysis reveals the stability of the synthesized electrode. - Highlights: • Nano Pt covered Ti with higher electrochemical activity was synthesized. • Efficiency of nano Pt coated titanium was double than polycrystalline bulk Pt. • The coating was intact post experiment in very aggressive environment of HNO3

  20. A New Process Study on Comprehensive Utilization of NOx from Nitric Acid Plant

    Institute of Scientific and Technical Information of China (English)

    Zhou Hou-zhen; Liang Hua

    2003-01-01

    Based on studies of controlling NOx from nitric acid exhaust gas domestic and abroad, this paper has developed a new technique on removal of NOx and production of a by-product with high added value-- MnO2. Experiment shows, pyrolusite, whose valid composition is MnO2, of absorbing NOx has the following characteristics: quick, low cost, no secondary pollutant. Moreover, exhaust gas can attain the required standards. If the temperature of the pyrolusite serum is 30℃, pH=4, containing 90 g/L MnO2, the absorptivity for 3 000 mg/m3 NOx is 89.2%. Furthermore,few of the impurities in pyrolusite dissolve in the absorption mother solution. The purification cost of product is very low.The purity of end product MnO2 is more than 99. 995% after purifying. Therefore, it is workable for the new technique on economy and technology. There are also obvious environmental benefits and marked economic returns.

  1. Formation and electrical characteristics of silicon dioxide layers by use of nitric acid oxidation method

    International Nuclear Information System (INIS)

    SiO2/Si structure can be formed at low temperatures by use of nitric acid (HNO3) oxidation of Si (NAOS) method. When Si wafers are immersed in ∼ 40 wt% HNO3 solutions at 108 deg C, ∼ 1 nm SiO2 layers are formed. The subsequent immersion in 68 wt% HNO3 (i.e., azeotropic mixture of HNO3 with water) at 121 deg C increases the SiO2 thickness. The 3,5 nm-thick SiO2 layers produced by this two-step NAOS method possess a considerably low leakage current density (e.g. 1 x 102 A/cmi2 at the forward gate bias, VG, of 1.5 V), in spite of the low temperature oxidation, and further decreased (e.g., 8 x 104 A/cm2 at VG = 1.5 V) by post-metallization annealing at 250 deg C in hydrogen atmosphere. In order to increase the SiO2 thickness, a bias voltage is applied during the NAOS method. When 10 V is applied to Si with respect to a Pt counter electrode both immersed in 1 M HNO3 solutions at 25 deg C, SiO2 layers with 8 nm thickness can be formed for 1 h(Authors)

  2. Investigation of sorption of palladium, ruthenium and rhodium ions from nitric acid solutions sorbents of different sorts

    International Nuclear Information System (INIS)

    Data are obtained on the Pd, Ru and Rh platinum metal ion sorption from nitric acid solutions on ion-exchange resins and nonorganic sorbents of different classes. It is determined that the sorbent capacity in relation to palladium is 1-2 orders higher of corresponding capacities in relation to ruthenium and rhodium. Series of sorption ability of sorbents are determined in relation to ions of considered elements in 3 mol/l HNO3

  3. AtNOA1 modulates nitric oxide accumulation and stomatal closure induced by salicylic acid in Arabidopsis

    OpenAIRE

    Sun, Li Rong; Hao, Fu Shun; Lu, Bao Shi; Ma, Li Ya

    2010-01-01

    Phytohormone salicylic acid (SA) has been documented to induce nitric oxide (NO) generation and stomatal closure in plants. However, the cellular components mediating these processes are limited. Here, we report that NO synthesis in guard cells and stomatal closure are markedly induced by SA in Arabidopsis wild type plants, whereas these effects caused by SA are suppressed significantly in noa1 T-DNA mutant plants. These results suggest that AtNOA1 regulates SA-triggered NO accumulation and s...

  4. Effect of temperature on strontium extraction from nitric acid medium using crown ether - aliphatic alcohol as the organic solvent

    International Nuclear Information System (INIS)

    The extraction of Sr(II) from 4.0 M nitric acid was carried out employing dicyclohexano 18 crown 6 (DCH18C6) in octanol and its mixtures with butanol at varying temperature. The thermodynamic parameter ΔH was computed from the Van't Hoff plot and ΔS and ΔG values were calculated. An interesting trend was observed in the enthalpy and entropy changes with varying diluent concentration. (author)

  5. Co-Mn-Al Spinel Catalyst for Removal of N2O from Nitric Acid Plant Tail Gases

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Karásková, K.; Kovanda, F.; Jirátová, Květa; Šrámek, J.; Kustrowski, P.; Chromčáková, Ž.; Kočí, K.; Borovec, K.; Dej, M.

    Prague : Heyrovsky Institut of Physical Chemistry of the ASCR, v. v .i, 2013 - (Žilková, N.; Horáček, M.), Po17 ISBN 978-80-87351-27-7. [Symposium on Catalysis /45./. Prague (CZ), 04.11.2013-06.11.2013] Institutional support: RVO:67985858 Keywords : Co-Mn-Al mixed oxide * nitric acid plant * catalysts Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.jh-inst.cas.cz/~catsymp/

  6. Determination of Copper-Based Fungicides by Flame Atomic Absorption Spectrometry Using Digestion Procedure with Sulfuric and Nitric Acid

    OpenAIRE

    Jelena Milinović; Rada Đurović

    2007-01-01

    Copper-based fungicides can be effectively digested by treatment with a mixture of concentrated sulfuric and nitric acid in exactly 15 minutes for the rapid determination via copper using flame atomic absorption spectrometry (AAS). Under optimum conditions, the results of copper fungicide analysis were consistent to those obtained by the AOAC’s recommended method. Recovery values ranged from 98.63 to 103.40%. Relative standard deviation values are lower than 2%. The proposed digestion procedu...

  7. Synthesis and evaluation of different thio-modified cellulose resins for the removal of mercury (II) ion from highly acidic aqueous solutions.

    Science.gov (United States)

    Takagai, Yoshitaka; Shibata, Atsushi; Kiyokawa, Shigemi; Takase, Tsugiko

    2011-01-15

    Seven different types of thio- and/or amine-modified cellulose resin materials were synthesized and their mercury (II) ion adsorption properties determined. All seven resins showed good mercury (II) adsorption capability in the more neutral pH regions. However, the o-benzenedithiol- and o-aminothiophenol-modified cellulosic resins were found to be very effective in removing mercury (II) ions from strongly acidic media. For example, 93.5-100% mercury (II) ion recoveries from very acid aqueous solutions (nitric acid concentration ranged from 0.1 to 2.0 mol/L) were obtained using the o-benzenedithiol-modified resin while recoveries ranged from ca. 50% to 60% for the o-aminothiophenol-modified resin. An adsorption capacity of 23 mg (as Hg atoms) per gram of resin was observed for the o-benzenedithiol-modified cellulose in the presence of 1.0 mol/L nitric acid. This same resin shows very good selectivity for mercury (II) as only ruthenium (II) also somewhat adsorbed onto it out of 14 other metal ions studied (Ag(+), Al(3+), As(3+), Co(2+), Cd(2+), Cr(3+), Cu(2+), Fe(3+), Mn(2+), Ni(2+), Pt(2+), Pb(2+), Ru(2+), and Zn(2+)). PMID:20974469

  8. Neodymium(3) complexing with bischloromethylphosphinic acid in aqueous solution

    International Nuclear Information System (INIS)

    High resolution spectrography is used to study Nd3+ complexing with (ClCH2)2POOH(HL) in aqueous solution. NdL2+ complex (lg Kstab = 0.44±0.04) with the corresponding absorption band with a maximum at λ=4283 A is formed in a system

  9. Thermal And Spectroscopic Analyses Of Next Generation Caustic Side Solvent Extraction Solvent Contacted With 3, 8, And 16 Molar Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F. F.; Fink, S. D.

    2011-12-07

    A new solvent system referred to as Next Generation Solvent or NGS, has been developed at Oak Ridge National Laboratory for the removal of cesium from alkaline solutions in the Caustic Side Solvent Extraction process. The NGS is proposed for deployment at MCU{sup a} and at the Salt Waste Processing Facility. This work investigated the chemical compatibility between NGS and 16 M, 8 M, and 3 M nitric acid from contact that may occur in handling of analytical samples from MCU or, for 3 M acid, which may occur during contactor cleaning operations at MCU. This work shows that reactions occurred between NGS components and the high molarity nitric acid. Reaction rates are much faster in 8 M and 16 M nitric acid than in 3 M nitric acid. In the case of 16 M and 8 M nitric acid, the nitric acid reacts with the extractant to produce initially organo-nitrate species. The reaction also releases soluble fluorinated alcohols such as tetrafluoropropanol. With longer contact time, the modifier reacts to produce a tarry substance with evolved gases (NO{sub x} and possibly CO). Calorimetric analysis of the reaction product mixtures revealed that the organo-nitrates reaction products are not explosive and will not deflagrate.

  10. Thermal And Spectroscopic Analyses Of Next Generation Caustic Side Solvent Extraction Solvent Contacted With 3, 8, And 16 Molar Nitric Acid

    International Nuclear Information System (INIS)

    A new solvent system referred to as Next Generation Solvent or NGS, has been developed at Oak Ridge National Laboratory for the removal of cesium from alkaline solutions in the Caustic Side Solvent Extraction process. The NGS is proposed for deployment at MCUa and at the Salt Waste Processing Facility. This work investigated the chemical compatibility between NGS and 16 M, 8 M, and 3 M nitric acid from contact that may occur in handling of analytical samples from MCU or, for 3 M acid, which may occur during contactor cleaning operations at MCU. This work shows that reactions occurred between NGS components and the high molarity nitric acid. Reaction rates are much faster in 8 M and 16 M nitric acid than in 3 M nitric acid. In the case of 16 M and 8 M nitric acid, the nitric acid reacts with the extractant to produce initially organo-nitrate species. The reaction also releases soluble fluorinated alcohols such as tetrafluoropropanol. With longer contact time, the modifier reacts to produce a tarry substance with evolved gases (NOx and possibly CO). Calorimetric analysis of the reaction product mixtures revealed that the organo-nitrates reaction products are not explosive and will not deflagrate

  11. Thermal And Spectroscopic Analyses Of Next Generation Caustic Side Solvent Extraction Solvent Contacted With 3, 8, And 16 Molar Nitric Acid

    International Nuclear Information System (INIS)

    A new solvent system referred to as Next Generation Solvent or NGS, has been developed at Oak Ridge National Laboratory for the removal of cesium from alkaline solutions in the Caustic Side Solvent Extraction process. NGS is proposed for deployment at MCU and at the Salt Waste Processing Facility. This work investigated the chemical compatibility between NGS and 16 M, 8 M, and 3 M nitric acid from contact that may occur in handling of analytical samples from MCU or, for 3 M acid, which may occur during contactor cleaning operations at MCU. This work shows that reactions occurred between NGS components and the high molarity nitric acid. In the case of 16 M and 8 M nitric acid, initially organo-nitrate groups are generated and attach to the modifier and that with time oxidation reactions convert the modifier into a tarry substance with gases (NOx and possibly CO) evolving. Calorimetric analysis of the organonitrate revealed the reaction products are not explosive nor will they deflagrate. NGS exposure to 3 M nitric acid resulted in much slower reaction kinetics and that the generated products were not energetic. We recommended conducting Accelerated Rate calorimetry on the materials generated in the 16 M and 8 M nitric acid test. Also, we recommend continue monitoring of the samples contacting NGS with 3 M nitric acid.

  12. Non Dispersive Solvent Extraction (NDSX) for the separation of samarium from nitric acid medium using DNPPA in a hollow fibre membrane module

    International Nuclear Information System (INIS)

    There is a growing interest in recent years either to eliminate the use of hazardous organic solvents or to limit their inventory in the separation scheme for the purification of metal ion from different types of aqueous streams. Hollow fibre contractor fits this objective perfectly, which not only minimizes the use of large volume of solvents as often encountered in conventional solvent extraction technique, but also offers the large surface area for fast mass transfer kinetics. In the present work we have used a in-house assembled membrane-contactors modules made of Accurel PP50/280 hydrophobic hollow fibres (MEMBRANA society) in a glass sealed with epoxy resin at both the sides for the non- dispersive solvent extraction of Sm(III) from nitric acid medium with di-nonyl phenyl phosphoric acid (DNPPA) dissolved in dodecane. The module contains 50 polypropylene hollow fibres of an average length of 20 cm. The used polypropylene hollow fibres have internal diameter and thickness of 280 μm and 50 μm respectively. The average pore size and porosity were 0.05 μm and the 50-55% respectively and the average surface area was 0.128Cm2.Cm-3. The NDSX experiments were carried out by pumping Sm (III) solution at varying concentration of HNO3 (0.1 to 2M) through the tube side and organic solvent (0.2M DNPPA) through the shell side of HFM module. The volume of aqueous and organic phases were 200 mL each. Experiments were performed under different hydrodynamic conditions under counter current mode in a closed system. Except for flow rate variation test run, the flow rate of aqueous and organic solution was fixed at 5mL/min. Operation time of 60 min. was found to be optimum for quantitative extraction of Sm(III) from aqueous solution to organic phase. Extraction of Sm (III) decreased with increase in HNO3 concentration following the cation exchange mechanism for acidic extractant DNPPA. Increase in Sm(III) concentration from 0.5g/L to 10 g/L in 1M HNO3 led to decrease in

  13. Sorption of uranyl and thorium(IV) ions by dodecavanadium acid from diluted nitric acid solutions

    International Nuclear Information System (INIS)

    Sorption of uranyl by dodecavanadium acid (DDVA) proceeds according to ion exchange mechanism in the region of relatively low values of its concentration - (0.8-2.0) x 10-3 mol/l. Th(IV) sorption practically not depends on solution pH value in interval of pH 1.5-2.5 and changes significantly in dependence on its initial concentration. Maximal values of DDVA capacity differ for Th(IV) and UO22+ (9 and 6.3 mg-equi/g) respectively. X-ray phase analysis establishes the composition of uranyl compounds obtained during DDVA contact with concentrated solutions of uranyl nitrate that is UO2(VO3)2·nH2O

  14. Effects of cold work, sensitization treatment and its combination on corrosion behavior of stainless steels in nitric acid

    International Nuclear Information System (INIS)

    In the Purex reprocessing process, the spent nuclear fuels from light water reactors are dissolved in nitric acid to separate and recover the fissile materials such as Uranium and Plutonium from the radioactive fission products. To ensure safety and reliable operation of the reprocessing plant, superior corrosion resistance is required to the structural materials of the plant, and stainless steels have been used as one of the main structural materials because of its very good performance in a nitric acid environment. Corrosion behavior of stainless steels was investigated in nitric acid for the effect of cold work, sensitization heat treatment and its combination. Corrosion rate of solution-treated Type 304 with extra low carbon (304 ELC) increased with time and reached constant values after 1,000 h of immersion time. Constant corrosion rates, however, were obtained for 25Cr-20Ni-Nb (310 Nb) from the initial stage of immersion. Cold work mitigated corrosion of the solution-treated stainless steels. The effect of cold work was different on the two stainless steels with sensitization heat treatment, showing accelerated corrosion for 304 ELC. The corrosion resistance of 310 Nb was superior to 304ELC after all the treatments. Chromium concentration of the sensitization treated 304 ELC was lower in the grain-boundary region than that of the solution-treated one, although no chromium carbide precipitation was observed. This might be the cause of corrosion enhancement by sensitization treatment

  15. Remedial investigation report on the abandoned nitric acid pipeline at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    Upper East Fork Poplar Creek OU-2 consists of the Abandoned Nitric Acid Pipeline. This pipeline was installed in 1951 to transport liquid wastes ∼ 4,800 ft from Buildings 9212, 9215, and 9206 to the S-3 Ponds. Materials known to have been discharged through the pipeline include nitric acid, depleted and enriched uranium, various metal nitrates, salts, and lead skimmings. A total of nineteen locations were chosen to be investigated along the pipeline for the first phase of this Remedial Investigation. Sampling consisted of drilling down to obtain a soil sample at a depth immediately below the pipeline. Additional samples were obtained deeper in the subsurface depending upon the depth of the pipeline, the depth of the water table, and the point of auger refusal. The nineteen samples collected below the pipeline were analyzed by the Y-12 Plant laboratory for metals, nitrate/nitrite, and isotopic uranium. Samples collected from three boreholes were also analyzed for volatile organic compounds because these samples produced a response with organic vapor monitoring equipment. The results of the baseline human health risk assessment for the Abandoned Nitric Acid Pipeline contaminants of potential concern show no unacceptable risks to human health via incidental ingestion of soil, inhalation of dust, dermal contact with the soil, or external exposure to radionuclides in the ANAP soils, under the construction worker and/or the residential land-use scenarios

  16. Remedial investigation report on the abandoned nitric acid pipeline at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-01

    Upper East Fork Poplar Creek OU-2 consists of the Abandoned Nitric Acid Pipeline. This pipeline was installed in 1951 to transport liquid wastes {approximately} 4,800 ft from Buildings 9212, 9215, and 9206 to the S-3 Ponds. Materials known to have been discharged through the pipeline include nitric acid, depleted and enriched uranium, various metal nitrates, salts, and lead skimmings. A total of nineteen locations were chosen to be investigated along the pipeline for the first phase of this Remedial Investigation. Sampling consisted of drilling down to obtain a soil sample at a depth immediately below the pipeline. Additional samples were obtained deeper in the subsurface depending upon the depth of the pipeline, the depth of the water table, and the point of auger refusal. The nineteen samples collected below the pipeline were analyzed by the Y-12 Plant laboratory for metals, nitrate/nitrite, and isotopic uranium. Samples collected from three boreholes were also analyzed for volatile organic compounds because these samples produced a response with organic vapor monitoring equipment. The results of the baseline human health risk assessment for the Abandoned Nitric Acid Pipeline contaminants of potential concern show no unacceptable risks to human health via incidental ingestion of soil, inhalation of dust, dermal contact with the soil, or external exposure to radionuclides in the ANAP soils, under the construction worker and/or the residential land-use scenarios.

  17. Nitric acid in the stratosphere based on Odin observations from 2001 to 2007 – Part 1: A global climatology

    Directory of Open Access Journals (Sweden)

    M. L. Santee

    2008-05-01

    Full Text Available The Sub-Millimetre Radiometer (SMR on board the Odin satellite, launched in February 2001, observes thermal emissions of stratospheric nitric acid (HNO3 originating from the Earth limb in a band centred at 544.6 GHz. Height-resolved measurements of the global distribution of nitric acid in the stratosphere between ~18–45 km (~1.5–60 hPa were performed approximately on two observation days per week. An HNO3 climatology based on roughly 6 years of observations from August 2001 to December 2007 was created. The study highlights the spatial and seasonal variation of nitric acid in the stratosphere, characterised by a pronounced seasonal cycle at middle and high latitudes with maxima during late fall and minima during spring, strong denitrification in the lower stratosphere of the Antarctic polar vortex during winter (the irreversible removal of NOy by the sedimentation of cloud particles containing HNO3, as well as high quantities of HNO3 formed every winter at high-latitudes in the middle and upper stratosphere. A strong inter-annual variability is observed in particular at high latitudes. A comparison with a stratospheric HNO3 climatology based on UARS/MLS measurements from the 1990s shows a good consistency and agreement of the main morphological features in the potential temperature range ~465 to ~960 K, if the different characteristics of the data sets such as altitude range and resolution are considered.

  18. Development of a Quantum Cascade Laser-Based Detector for Ammonia and Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Zahniser, Mark S.; Nelson, David D.; McManus, J. Barry; Shorter, Joanne H.; Herndon, Scott C.; Jimenez, Rodrigo

    2005-12-31

    We have developed a compact, robust, atmospheric trace gas detector based on mid-infrared absorption spectroscopy using pulsed quantum cascade (QC) lasers. The spectrometer is suitable for airborne measurements of ammonia, nitric acid, formaldehyde, formic acid, methane, nitrous oxide, carbon monoxide, nitrogen dioxide and other gases that have line-resolved absorption spectra in the mid-infrared spectral region. The QC laser light source operates near room temperature with thermal electric cooling instead of liquid nitrogen which has been previously required for semiconductor lasers in the mid-infrared spectral region. The QC lasers have sufficient output power so that thermal electric cooled detectors may be used in many applications with lower precision requirements. The instrument developed in this program has been used in several field campaigns from both the Aerodyne Mobile Laboratory and from the NOAA WP3 aircraft. The Phase II program has resulted in more than 10 archival publications describing the technology and its applications. Over 12 instruments based on this design have been sold to research groups in Europe and the United States making the program both a commercial as well as a technological success. Anticipated Benefits The development of a sensitive, cryogen-free, mid-infrared absorption method for atmospheric trace gas detection will have wide benefits for atmospheric and environmental research and broader potential commercial applications in areas such as medical diagnostic and industrial process monitoring of gaseous compounds. Examples include air pollution monitoring, breath analysis, combustion exhaust diagnostics, and plasma diagnostics for semi-conductor fabrication. The substitution of near-room temperature QC lasers for cryogenic lead salt TDLs and the resulting simplifications in instrument design and operation will greatly expand the range of applications.

  19. Change in the amino acid composition of calf skin collagen after. gamma. -irradiation in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Duzhenkova, N.A.; Savich, A.V. (Institut Biofiziki, Moscow (USSR))

    A study was made of the amino acid composition of calf skin collagen after ..gamma..-irradiation (/sup 60/Co) of 2.5x10/sup -6/ M aerated aqueous protein solution within the dose range from 30 to 2000 Gy. The radiosensitivity of amino acid residues was compared.

  20. Selectivity of colour reactions between elements and organic reagents in organo-aqueous acetic acid media

    International Nuclear Information System (INIS)

    Reasons, responsible for selectivity of photometric reactions in organo-aqueous acetic acid media, have been studied taking aluminium, gallium, and indium reactions as examples. Solution-and paper electrophoresis as well as distribution chromatography were used to examine the state of the elements in various media, including those for most selective determination of aluminium in the presence of gallium and indium. A high selectivity is due to the formation of an electrically neutral species of aluminium. And chloride complexes of gallium and indium in organo-aqueous acetic acid media. Coloured ternary complexes of aluminium with organic reagents and phosphoric acid are formed in the presence of the latter

  1. CATALYTIC GENERATION OF HYDROGEN FROM BIOMASS DERIVED LACTIC ACID VIA AQUEOUS PHASE REFORMING

    OpenAIRE

    Bosilj, Monika

    2015-01-01

    Hydrogen production from aqueous phase reforming (APR) of organic acids in aqueous phase and from residue of a biomass decomposition process over 3 wt% Pt/ZrO2 has been studied in the absence and presence of barium ions. The results have been compared with Pt/TiO2, Pt/C and Ni/C catalysts. Having identified barium hydroxide as a promising reagent in combination with Pt/ZrO2 catalyst for the hydrogen production out of organic acids, the method for the lactic acid conversion was extended. Lacti...

  2. Extraction of lanthanide(III) and uranyl(VI) from nitric acid solution by N,N'-dimethyl-N,N'-dibutylmalonamide

    International Nuclear Information System (INIS)

    The extractive properties of N,N'-dimethyl-N,N'-dibutylmalonamide (DMDBMA) and the loading capacity of extraction solvents containing DMDBMA for lanthanide(III) and uranyl(VI) ions in nitric acid solution were investigated. The dependence of the distribution ratio on the concentration of nitric acid shows that DMDBMA has an ability to extract uranyl(VI) ions, while the extracting capacity for lanthanide(III) ions is not enough for the application in practice. 17 refs., 10 figs., 4 tabs

  3. Fast and Simultaneous Determination of Pu(Ⅳ) and Nitric Acid in Spent Nuclear Fuel Reprocessing Sample by Near Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI; Ding-ming; ZHANG; Li-hua; WANG; Ling; GONG; Yan-ping; FAN; De-jun; YI; Bao-shan; CHEN; Qiang; JI; Yong-chao; WU; Ji-zong

    2013-01-01

    Determination of Pu(Ⅳ)and nitric acid plays significant role in nuclear fuel reprocessing plant to control process accurately and timely.Coupling C-T fixed-type grating with InGaAs detector,a new novel analytical system for simultaneous measurement of nitric acid and Pu(Ⅳ)was developed by our working group.After obtaining near infrared absorptive spectra by the spectroscopic instrument,the spectra data

  4. Comparing the effects of inorganic nitrate and allopurinol in renovascular complications of metabolic syndrome in rats: role of nitric oxide and uric acid

    OpenAIRE

    Essawy, Soha S.; Abdel-Sater, Khaled A.; Elbaz, Amani A.

    2013-01-01

    Introduction The epidemic of metabolic syndrome is increasing worldwide and correlates with elevation in serum uric acid and marked increase in total fructose intake. Fructose raises uric acid and the latter inhibits nitric oxide bioavailability. We hypothesized that fructose-induced hyperuricemia may have a pathogenic role in metabolic syndrome and treatment of hyperuricemia or increased nitric oxide may improve it. Material and methods Two experiments were performed. Male Sprague-Dawley rat...

  5. Improvement in Aqueous Solubility of Retinoic Acid Receptor (RAR) Agonists by Bending the Molecular Structure.

    Science.gov (United States)

    Hiramatsu, Michiaki; Ichikawa, Yuki; Tomoshige, Shusuke; Makishima, Makoto; Muranaka, Atsuya; Uchiyama, Masanobu; Yamaguchi, Takao; Hashimoto, Yuichi; Ishikawa, Minoru

    2016-08-01

    Aqueous solubility is a key requirement for many functional molecules, e. g., drug candidates. Decrease of the partition coefficient (log P) by chemical modification, i.e., introduction of hydrophilic group(s) into molecules, is a classical strategy for improving aqueous solubility. We have been investigating alternative strategies for improving the aqueous solubility of pharmaceutical compounds by disrupting intermolecular interactions. Here, we show that introducing a bend into the molecular structure of retinoic acid receptor (RAR) agonists by changing the substitution pattern from para to meta or ortho dramatically enhances aqueous solubility by up to 890-fold. We found that meta analogs exhibit similar hydrophobicity to the parent para compound, and have lower melting points, supporting the idea that the increase of aqueous solubility was due to decreased intermolecular interactions in the solid state as a result of the structural changes. PMID:27378357

  6. 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)

    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)

  7. Versatile electrochemical coatings and surface layers from aqueous methanesulfonic acid

    OpenAIRE

    Walsh, F. C.; Ponce De Leon, Carlos

    2014-01-01

    Ever tightening environmental pressure together with the continued need for coatings able to meet challenging service environments have stimulated advances in coating technology. In the case of electrochemical techniques, the classical techniques of electrodeposition and anodising are being upgraded to meet the need for modern surface engineering coatings (including nanostructured films) on metals. A major challenge is to retain conventional processing, including aqueous solutions, simple pow...

  8. Study on the effect of gamma radiolysis on the chromatographic composition profile of tri-isoAmyl-phosphate-n-dodecane-nitric acid system

    International Nuclear Information System (INIS)

    Tri-Iso-Amyl phosphate (TiAP), a higher homologue of tri-butyl phosphate (TBP) is the solvent proposed for the reprocessing of the spent nuclear fuel of Fast Breeder Reactors (FBR) origin. TiAP-n-dodecane has extraction behavior comparable to that of TBP-n-dodecane system, without third phase formation and an aqueous solubility ∼ 19mg/L, that is far too less in case as compared to that with TBP(∼400gm/L). We have initiated our study to examine the radiolytic degradation behavior of TiAP-n-dodecane in comparison to that of TBP and explore its full potential for reprocessing of spent nuclear fuels. A 30% mixture of TiAP with n-dodecane equilibrated with nitric acid of concentrations 2M has been subjected to steady state gamma radiolysis using 60Co source. The samples were irradiated for increasing absorbed dose of 6,12 and 18M rad. Each of these samples were subjected to gas chromatographic analysis under optimised condition using thermal conductivity detector. Separately, these samples were also methylated using diazomethane for the determination of acidic phosphate species as their volatile methyl ester

  9. EFFECT OF TEMPERATURE AND CONCENTRATION ON THE VISCOSITY OF AQUEOUS SOLUTIONS OF 3-AMINOPROPANOIC ACID, 4-AMINOBUTANOIC ACID, 5-AMINOPENTANOIC ACID, 6-AMINOHEXANOIC ACID

    Directory of Open Access Journals (Sweden)

    Carmen María Romero

    2011-12-01

    Full Text Available In this work we present the effect of temperatureon the viscosities of aqueous solutionsof 3-aminopropanoic acid, 4-aminobutanoicacid, 5-aminopentanoic acidand 6-aminohexanoic acid as a functionof concentration. The experimental measurementswere done from 293.15 K to308.15 K. At each temperature the experimentaldata were fi tted to the Tsangaris-Martin equation and the B viscosity coefficient was determined. The dependenceof the B coeffi cients on the number ofcarbon atoms of the amino acids is linear,so the contribution of polar and apolargroups was established. The results areinterpreted in terms of amino acid hydration.

  10. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    Directory of Open Access Journals (Sweden)

    Kabljanac, Ž.

    2011-11-01

    Full Text Available This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comparison with designed capacity for one production line is shown in the Table 1. Shown is the effectiveness of selective catalytic reduction in the temperature range of the tail gas from 180 to 230 °C with direct application of liquid ammonia, without prior evaporation to gaseous state. The results of inlet and outlet concentrations of nitrous oxides in the tail gas of the nitric acid production process are shown in Figures 1 and 2. Figure 3 shows the temperature dependence of the selective catalytic reduction of nitrous oxides expressed as NO2in the tail gas of nitric acid production with the application of a constant mass flow of liquid ammonia of 13,0 kg h-1 and average inlet mass concentration of the nitrous oxides expressed as NO2of 800,0 mgm-3 during 100 % production capacity. The specially designed liquid-ammonia direct-dosing system along with the effective homogenization of the tail gas resulted in emission levels of nitrous oxides expressed as NO2 in tail gas ranging from 100,0 to 185,0 mg m-3. The applied low-temperature selective catalytic reduction of the nitrous oxides in the tail gases by direct use of liquid ammonia is shown in Figure 4. It is shown that low-temperature selective catalytic reduction with direct application of liquid ammonia opens a new opportunity in the reduction of nitrous oxide emissions during nitric acid production without the risk of dangerous ammonium nitrate occurring in the process of subsequent energy utilization of

  11. Pretreatment of rice straw with combined process using dilute sulfuric acid and aqueous ammonia

    OpenAIRE

    Kim, Sung Bong; Lee, Sang Jun; Lee, Ju Hun; Jung, You Ree; Thapa, Laxmi Prasad; Kim, Jun Seok; Um, Youngsoon; Park, Chulhwan; Kim, Seung Wook

    2013-01-01

    Background Use of lignocellulosic biomass has received attention lately because it can be converted into various versatile chemical compounds by biological processes. In this study, a two-step pretreatment with dilute sulfuric acid and aqueous ammonia was performed efficiently on rice straw to obtain fermentable sugar. The soaking in aqueous ammonia process was also optimized by a statistical method. Results Response surface methodology was employed. The determination coefficient (R2) value w...

  12. Biochemistry of Nitric Oxide

    OpenAIRE

    Habib, Safia; Ali, Asif

    2011-01-01

    Nitric oxide (NO) a free radical having both cytoprotective as well as tumor promoting agent is formed from l-arginine by converting it to l-citrulline via nitric oxide synthase enzymes. The reaction product of nitric oxide with superoxide generates potent oxidizing agent, peroxynitrite which is the main mediator of tissue and cellular injury. Peroxynitrite is reactive towards many biomolecules which includes amino acids, nucleic acid bases; metal containing compounds, etc. NO metabolites may...

  13. Selective extraction of plutonium from nitric acid medium by bifunctional polyethersulfone beads for quantification with thermal ionisation mass spectrometry

    International Nuclear Information System (INIS)

    Polyethersulfone (PES) magnetic beads were prepared by phase inversion technique. The beads were grafted with two monomers, viz. 2-hydroxyethylmethacrylate phosphoric acid (HEMP) and (3-acrylamidopropyl)trimethyl ammonium chloride (AMAC), by photo-induced free radical polymerization. Effect of different HNO3 concentrations on the sorption profiles of Am(III) and Pu(IV) was studied using the grafted PES beads. The beads were found to extract plutonium quantitatively from high nitric acid medium (3-8 M). The effect of presence of competing actinide, e.g. U(VI), on the sorption of Pu(IV) was also studied. (author)

  14. Dissolution Of Plutonium Metal Using Nitric Acid Solutions Containing Potassium Fluoride

    International Nuclear Information System (INIS)

    The deinventory and deactivation of the Savannah River Site's (SRS's) FB-Line facility required the disposition of approximately 2000 items from the facility's vaults. Plutonium (Pu) scraps and residues which do not meet criteria for conversion to a mixed oxide fuel will be dissolved and the solution stored for subsequent disposition. Some of the items scheduled for dissolution are composite materials containing Pu and tantalum (Ta) metals. The preferred approach for handling this material is to dissolve the Pu metal, rinse the Ta metal with water to remove residual acid, and burn the Ta metal. The use of a 4 M nitric acid (HNO3) solution containing 0.2 M potassium fluoride (KF) was initially recommended for the dissolution of approximately 500 g of Pu metal. However, prior to the use of the flowsheet in the SRS facility, a new processing plan was proposed in which the feed to the dissolver could contain up to 1250 g of Pu metal. To evaluate the use of a larger batch size and subsequent issues associated with the precipitation of plutonium-containing solids from the dissolving solution, scaled experiments were performed using Pu metal and samples of the composite material. In the initial experiment, incomplete dissolution of a Pu metal sample demonstrated that a 1250 g batch size was not feasible in the HB-Line dissolver. Approximately 45% of the Pu was solubilized in 4 h. The remaining Pu metal was converted to plutonium oxide (PuO2). Based on this work, the dissolution of 500 g of Pu metal using a 4-6 h cycle time was recommended for the HB-Line facility. Three dissolution experiments were subsequently performed using samples of the Pu/Ta composite material to demonstrate conditions which reduced the risk of precipitating a double fluoride salt containing Pu and K from the dissolving solution. In these experiments, the KF concentration was reduced from 0.2 M to either 0.15 or 0.175 M. With the use of 4 M HNO3 and a reduction in the KF concentration to 0.175 M

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Hyejeong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Department of Food Science and Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Lim, Sangyong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Jo, Cheorun [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Chung, Jinwoo [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Kim, Soohyun [Glycomics Team, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Kwon, Joong-Ho [Department of Food Science and Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kim, Dongho [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of)], E-mail: fungikim@kaeri.re.kr

    2008-06-15

    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.

  17. Kinetics of oxidation of ethyldigol by vanadium(V) in aqueous acidic medium

    International Nuclear Information System (INIS)

    The kinetics of oxidation of ethyldigol by vanadium(V) in aqueous acidic medium has been carried out. The reaction is first order with respect to vanadium(V) and the substrate and is acid catalysed. Hammett acidity function (H0) and Bunnett hypothesis have been applied. The formation of free radicals during the course of the reaction has been indicated. A probable reaction mechansim is proposed. (Author)

  18. Summary Report on Gamma Radiolysis of TBP/n-dodecane in the Presence of Nitric Acid Using the Radiolysis/Hydrolysis Test Loop

    International Nuclear Information System (INIS)

    Design and installation has been completed for a state-of-the-art radiolysis/hydrolysis test loop system. The system is used to evaluate the effects of gamma radiolysis and acid hydrolysis on the stability and performance of solvent extraction process solvents. The test loop is comprised of two main sections; the solvent irradiation and hydrolysis loop and the solvent reconditioning loop. In the solvent irradiation and hydrolysis loop, aqueous and organic phases are mixed and circulated through a gamma irradiator until the desired absorbed dose is achieved. Irradiation of the mixed phases is more representative of actual conditions in a solvent extraction process. Additionally, the contact of the organic phase with the aqueous phase will subject the solvent components to hydrolysis. This hydrolysis can be accelerated by controlling the system at an elevated temperature. At defined intervals, the organic from the irradiation/hydrolysis loop will be transferred to the solvent reconditioning loop where the solvent is contacted with scrub, strip, and solvent wash solutions which simulate process flowsheet conditions. These two processes are repeated until the total desired dose is achieved. Since all viable solvent extraction components in an advanced fuel cycle must exhibit high radiolytic and hydrolytic stability, this test loop is not limited to any one solvent system but is applicable to all systems of interest. Also, the test loop is not limited to testing of process flowsheets. It is also a valuable tool in support of fundamental research on newly identified extractants/modifiers and the impact of gamma radiation on their stability in a dynamic environment. The investigation of the radiolysis of a TBP/n-dodecane process solvent in contact with aqueous nitric acid has been performed. These studies were intended to confirm/optimize the operability of the test loop system. Additionally, these data are directly applicable to numerous other solvent extraction

  19. Summary Report on Gamma Radiolysis of TBP/n-dodecane in the Presence of Nitric Acid Using the Radiolysis/Hydrolysis Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Dean R. Peterman; Bruce J. Mincher; Catherine L. Riddle; Richard D. Tillotson

    2010-08-01

    Design and installation has been completed for a state-of-the-art radiolysis/hydrolysis test loop system. The system is used to evaluate the effects of gamma radiolysis and acid hydrolysis on the stability and performance of solvent extraction process solvents. The test loop is comprised of two main sections; the solvent irradiation and hydrolysis loop and the solvent reconditioning loop. In the solvent irradiation and hydrolysis loop, aqueous and organic phases are mixed and circulated through a gamma irradiator until the desired absorbed dose is achieved. Irradiation of the mixed phases is more representative of actual conditions in a solvent extraction process. Additionally, the contact of the organic phase with the aqueous phase will subject the solvent components to hydrolysis. This hydrolysis can be accelerated by controlling the system at an elevated temperature. At defined intervals, the organic from the irradiation/hydrolysis loop will be transferred to the solvent reconditioning loop where the solvent is contacted with scrub, strip, and solvent wash solutions which simulate process flowsheet conditions. These two processes are repeated until the total desired dose is achieved. Since all viable solvent extraction components in an advanced fuel cycle must exhibit high radiolytic and hydrolytic stability, this test loop is not limited to any one solvent system but is applicable to all systems of interest. Also, the test loop is not limited to testing of process flowsheets. It is also a valuable tool in support of fundamental research on newly identified extractants/modifiers and the impact of gamma radiation on their stability in a dynamic environment. The investigation of the radiolysis of a TBP/n-dodecane process solvent in contact with aqueous nitric acid has been performed. These studies were intended to confirm/optimize the operability of the test loop system. Additionally, these data are directly applicable to numerous other solvent extraction

  20. Adsorption of organic acids from dilute aqueous solution onto activated carbon

    International Nuclear Information System (INIS)

    The radioisotope technique was used to study the removal of organic acid contaminants from dilute aqueous solutions onto activated carbon. Acetic acid, propionic acid, n-butyric acid, n-hexanoic acid and n-heptanoic acid were studied at 278, 298, and 3130K. Three bi-solute acid mixtures (acetic and propionic acids, acetic and butanoic acids, and propionic and butanoic acids) were studied at 278 and 2980K. Isotherms of the single-solute systems were obtained at three different temperatures in the very dilute concentration region (less than 1% by weight). These data are very important in the prediction of bi-solute equilibrium data. A Polanyi-based competitive adsorption potential theory was used to predict the bi-solute equilibrium uptakes. Average errors between calculated and experimental data ranges from 4% to 14%. It was found that the competitive adsorption potential theory gives slightly better results than the ideal adsorbed solution theory