Distribution Of Nitric Acid Research Articles

Comparison of activity coefficient models for the estimation of uranyl nitrate and nitric acid distribution coefficients in phosphoric solvent

The modelling of solvent extraction system is important for the process flow sheet design and optimization. The estimation of aqueous phase activity coefficients constitutes the major part of the thermodynamic modelling of solvent extraction system. Hence the selection of suitable activity coefficient models for the accurate description of aqueous electrolyte system encountered in the nuclear fuel reprocessing system is an important task which decides the accuracy and complexity of the modelling. In this work the accuracy of extended UNIQUAC (eUNIQUAC) activity coefficient model for the estimation of uranyl nitrate and nitric acid distribution coefficient in 1.1 M Tri Butyl Phosphate (TBP) and 1.1 M Tri iso Amyl Phosphate (TiAP) have been compared with the eNRTL, Pitzer and SIT activity coefficient models. eUNIQUAC model gave lowest RMSD (%) for the estimation of uranyl nitrate and nitric acid extraction in TiAP and TBP respectively.

Nitric Acid Extraction into a TODGA Solvent Modified with 1-Octanol

ABSTRACTDistribution data for the partition of nitric acid between nitric acid solution and a solvent phase comprising various combinations of TODGA, octanol, and inert kerosene diluent have been generated, covering a range of conditions from 0 to 9 mol/L HNO3(aq), 0–100% octanol, 0–0.4 mol/L TODGA over a temperature range from 10°C to 50°C. The data have been used to derive a model describing the nitric acid equilibrium between the phases suitable for incorporation in process models of the innovative SANEX process, for example. For the nitric acid/octanol/diluent system, it was found that an accurate prediction of nitric acid distribution could be achieved using a model allowing 1:1, 1:2, and 1:3 nitric acid/octanol adducts. For the nitric acid/TODGA/diluent system, the best models were found to be those allowing 4:1, 3:1, 2:1, 1:1, and 2:2 nitric acid/TODGA adducts. Superimposing the models for nitric acid distribution into the individual extractants and comparing with experimental results for the nitric acid/octanol/TODGA system showed systematic differences indicative of antagonistic and synergistic effects applying in the ranges 0.5–1.5 mol/L HNO3 and >1.5 mol/L HNO3, respectively. These effects were modelled by the inclusion of 0:1:2, 1:1:1, 2:1:3, and 3:1:2 nitric acid/TODGA/octanol adducts. The effect of temperature on nitric acid extraction was well described by an Arrhenius type expression with an activation energy of −25.7 kJ/mol. No diluent dependence was found for nitric acid extraction.

Solvent Extraction of Uranium with N,N-Di(2-Ethylhexyl)Octanamide from Nitric Acid Medium

ABSTRACTSolvent extraction of uranium from a nitric acid medium was performed with N,N-di(2-ethylhexyl)octanamide (DEHOA) by a single-stage batch method, and the distribution ratio equation of U(VI) was derived as , where [NO3‒]aq and [DEHOAFree]U represented the concentration of nitrate ion in the aqueous phase and free DEHOA concentration in the organic phase, respectively. Furthermore, the nitric acid distribution was also evaluated in the initial nitric acid range of 0.31‒7.2 mol/dm3 (M), and the distribution ratio equation was obtained as , where [H+]aq and [DEHOAFree]H represented the acid concentration in the aqueous phase and free DEHOA concentration in the organic phase, respectively. Batch experiments to evaluate the time dependence of U(VI) extraction and the U(VI) loading capacity of DEHOA were also performed. It was revealed that U(VI) extraction by DEHOA reached an equilibrium state within a few minutes, and the loading capacity was 0.71 M when the concentrations of DEHOA and nitric acid were 1.5 and 3.0 M, respectively.

Interannual variations of early winter Antarctic polar stratospheric cloud formation and nitric acid observed by CALIOP and MLS

Abstract. We use satellite-borne measurements collected over the last decade (2006–2015) from the Aura Microwave Limb Sounder (MLS) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) to investigate the nitric acid distribution and the properties of polar stratospheric clouds (PSCs) in the early winter Antarctic vortex. Frequently, at the very start of the winter, we find that synoptic-scale depletion of HNO3 can be detected in the inner vortex before the first lidar detection of geophysically associated PSCs. The generation of "sub-visible" PSCs can be explained as arising from the development of a solid particle population with low number densities and large particle sizes. Assumed to be composed of nitric acid trihydrate (NAT), the sub-visible PSCs form at ambient temperatures well above the ice frost point, but also above the temperature at which supercooled ternary solution (STS) grows out of the background supercooled binary solution (SBS) distribution. The temperature regime of their formation, inferred from the simultaneous uptake of ambient HNO3 into NAT and their Lagrangian temperature histories, is at a depression of a few kelvin with respect to the NAT existence threshold, TNAT. Therefore, their nucleation requires a considerable supersaturation of HNO3 over NAT, and is consistent with a recently described heterogeneous nucleation process on solid foreign nuclei immersed in liquid aerosol. We make a detailed investigation of the comparative limits of detection of PSCs and the resulting sequestration of HNO3 imposed by lidar, mid-infrared, and microwave techniques. We find that the temperature history of air parcels, in addition to the local ambient temperature, is an important factor in the relative frequency of formation of liquid/solid PSCs. We conclude that the initiation of NAT nucleation and the subsequent development of large NAT particles capable of sedimentation and denitrification in the early winter do not emanate from an ice-seeding process. Finally, we investigate the patterns of interannual variability and compare the relative formation frequency of liquid and solid PSCs in the Antarctic lower polar stratosphere using the results of a cluster analysis to synthesize the combined CALIOP and MLS measurements into a relatively small number of interrelated categories.

First characterization and validation of FORLI-HNO<sub>3</sub> vertical profiles retrieved from IASI/Metop

Abstract. Knowing the spatial and seasonal distributions of nitric acid (HNO3) around the globe is of great interest and allows us to comprehend the processes regulating stratospheric ozone, especially in the polar regions. Due to its unprecedented spatial and temporal sampling, the nadir-viewing Infrared Atmospheric Sounding Interferometer (IASI) is capable of sounding the atmosphere twice a day globally, with good spectral resolution and low noise. With the Fast Optimal Retrievals on Layers for IASI (FORLI) algorithm, we are retrieving, in near real time, columns as well as vertical profiles of several atmospheric species, among which is HNO3. We present in this paper the first characterization of the FORLI-HNO3 profile products, in terms of vertical sensitivity and error budgets. We show that the sensitivity of IASI to HNO3 is highest in the lower stratosphere (10–20 km), where the largest amounts of HNO3 are found, but that the vertical sensitivity of IASI only allows one level of information on the profile (degrees of freedom for signal, DOFS; ∼ 1). The sensitivity near the surface is negligible in most cases, and for this reason, a partial column (5–35 km) is used for the analyses. Both vertical profiles and partial columns are compared to FTIR ground-based measurements from the Network for the Detection of Atmospheric Composition Change (NDACC) to characterize the accuracy and precision of the FORLI-HNO3 product. The profile validation is conducted through the smoothing of the raw FTIR profiles by the IASI averaging kernels and gives good results, with a slight overestimation of IASI measurements in the upper troposphere/lower stratosphere (UTLS) at the six chosen stations (Thule, Kiruna, Jungfraujoch, Izaña, Lauder and Arrival Heights). The validation of the partial columns (5–35 km) is also conclusive with a mean correlation of 0.93 between IASI and the FTIR measurements. An initial survey of the HNO3 spatial and seasonal variabilities obtained from IASI measurements for a 1-year (2011) data set shows that the expected latitudinal gradient of concentrations from low to high latitudes and the large seasonal variability in polar regions (cycle amplitude around 30 % of the seasonal signal, peak to peak) are well represented by IASI data.

Influence of pressure (temperature) on the nitric acid distribution between the liquid and vapor in the course of evaporation of nitric acid radioactive waste

Analysis of the published dependences of the HNO3 distribution coefficient between the liquid and vapor in the system with water shows that these dependences are power functions with the exponent depending on the temperature (pressure) and emerge from the azeotropic point. The exponent is inversely proportional to the temperature, and its logarithm is directly proportional to the logarithm of the pressure. The pattern is preserved when a salting-out agent is present in the system and is described similarly when taking into account the hydration and hydrolysis of the cation and the degree of dissociation of sulfuric acid, as shown previously for atmospheric pressure. The dependences obtained are interpreted within the framework of the law of mass action (without activity coefficients) as dilution of the azeotropic compound HNO3(H2O)2 with water with the formation of an associated ionic liquid.

Effect of salting-out agents on nitric acid distribution between liquid and vapor in the course of evaporation of nitric acid radioactive waste

The database on the influence of concentrations of salting-out agents with different cation valence (Li+, Na+, K+, Cs+, NH4+, Mg2+, Ca2+, Cu2+, Zn2+, Al3+, Fe3+, La3+, Pu4+, UO22+ nitrates) and of H2SO4 on the HNO3 distribution between liquid and vapor at atmospheric pressure was verified and expanded by performing equilibrium evaporation experiments in an evaporator without reflux with circulation of the bottoms. This equilibrium can be described by the equation \(\log {\kern 1pt} {\alpha _H} = - 2.35 + 2\log \;{X_{\Sigma N{O_3}}}\) (where \({X_{\Sigma N{O_3}}}\) is the total concentration of nitrate ions in aqueous solution), taking into account partial binding of water due to hydration of the salting-out agent and apparent hydrolysis of polyvalent cations, and also incomplete dissociation of sulfuric acid. The suggested model is valid at \({X_{\Sigma N{O_3}}}\) from 3 to 16 M (azeotrope); at \({X_{\Sigma N{O_3}}}{\text{ < }}\;3\), Raoult’s law is observed (αH = const), which is confirmed by a number of examples. In this model, the additivity of the properties of the salting- out agents, taking into account the concentration of “free” water, is assumed, which allows calculation of the composition of the bottoms and distillate when evaporating waste of any composition from radiochemical plants.

A-train CALIOP and MLS observations of early winter Antarctic polar stratospheric clouds and nitric acid in 2008

Abstract. A-train Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Microwave Limb Sounder (MLS) observations are used to investigate the development of polar stratospheric clouds (PSCs) and the gas-phase nitric acid distribution in the early 2008 Antarctic winter. Observational evidence of gravity-wave activity is provided by Atmospheric Infrared Sounder (AIRS) radiances and infrared spectroscopic detection of nitric acid trihydrate (NAT) in PSCs is obtained from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Goddard Earth Observing System Data Assimilation System (GEOS-5 DAS) analyses are used to derive Lagrangian trajectories and to determine temperature-time histories of air parcels. We use CALIOP backscatter and depolarization measurements to classify PSCs and the MLS measurements to determine the corresponding gas-phase HNO3 as a function of temperature. For liquid PSCs the uptake of HNO3 follows the theoretical equilibrium curve for supercooled ternary solutions (STS), but at temperatures about 1 K lower as determined from GEOS-5. In the presence of solid phase PSCs, above the ice frost-point, the HNO3 depletion occurs over a wider range of temperatures (+2 to −7 K) distributed about the NAT equilibrium curve. Rapid gas-phase HNO3 depletion is first seen by MLS from from 23–25 May 2008, consisting of a decrease in the volume mixing ratio from 14 ppbv (parts per billion by volume) to 7 ppbv on the 46–32 hPa (hectopascal) pressure levels and accompanied by a 2–3 ppbv increase by renitrification at the 68 hPa pressure level. The observed region of depleted HNO3 is substantially smaller than the region bounded by the NAT existence temperature threshold. Temperature-time histories of air parcels demonstrate that the depletion is more clearly correlated with prior exposure to temperatures a few kelvin above the frost-point. From the combined data we infer the presence of large-size NAT particles with effective radii &gt;5–7 μm and low NAT number densities &lt;1 × 10−3 cm−3. This denitrification event is observed close to the pole in the Antarctic vortex before synoptic temperatures first fall below the ice frost point and before the widespread occurrence of large-scale NAT PSCs. An episode of mountain wave activity detected by AIRS on 28 May 2008 led to wave-ice formation in the rapid cooling phases over the Antarctic Peninsula and Ellsworth Mountains, seeding an outbreak of NAT PSCs that were detected by CALIOP and MIPAS. The NAT clouds formed at altitudes of 18–26 km in a polar freezing belt and appear to be composed of relatively small particles with estimated effective radii of around 1 μm and high NAT number densities &gt;0.2 cm−3. This NAT outbreak is similar to an event previously reported from MIPAS observations in mid-June 2003.

Third phase formation in the extraction of nitric acid and metal ions by octyl(phenyl)-N,N-diisobutyl carbamoyl methyl phosphine oxide (OΦCMPO) based solvents

Formation of a third phase in the extraction of nitric acid and metal ions such as Th(IV), U(VI), La(III), Ce(III), and Gd(III) by OΦCMPO based solvents has been investigated under various conditions. The limiting organic concentrations (LOC) and critical aqueous concentrations (CAC) for third phase formation in the extraction of nitric acid by 0.2 M OΦCMPO + 1.2 M TBP in n-tetradecane and 0.2 M OΦCMPO + 1.2 M TBP in n-hexadecane were measured as a function of temperature. Extraction of nitric acid by these solvents as a function of equilibrium aqueous phase acidity at 303 K has been studied. Distribution of nitric acid between diluent-rich phase (DP) and third phase (TP) in the extraction of nitric acid by these solvents has also been studied as a function of equilibrium aqueous phase acidity at 303 K. Densities of diluent-rich phase, third phase, and aqueous phase have been measured as a function of equilibrium aqueous phase acidity at 303 K. Third phase formation in the extraction of Th(IV), U(VI), La(...

Improvements in the profiles and distributions of nitric acid and nitrogen dioxide with the LIMS version 6 dataset

Abstract. The quality of the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) nitric acid (HNO3) and nitrogen dioxide (NO2) profiles and distributions of 1978/1979 are described after their processing with an updated, Version 6 (V6) algorithm and subsequent archival in 2002. Estimates of the precision and accuracy of both of those species are developed and provided herein. The character of the V6 HNO3 profiles is relatively unchanged from that of the earlier LIMS Version 5 (V5) profiles, except in the upper stratosphere where the interfering effects of CO2 are accounted for better with V6. The accuracy of the retrieved V6 NO2 is also significantly better in the middle and upper stratosphere, due to improvements in its spectral line parameters and in the reduced biases for the accompanying V6 temperature and water vapor profiles. As a result of these important updates, there is better agreement with theoretical calculations for profiles of the HNO3/NO2 ratio, day-to-night NO2 ratio, and with estimates of the production of NO2 in the mesosphere and its descent to the upper stratosphere during polar night. In particular, the findings for middle and upper stratospheric NO2 should also be more compatible with those obtained from more recent satellite sensors because the effects of the spin-splitting of the NO2 lines are accounted for now with the LIMS V6 algorithm. The improved precisions and more frequent retrievals of the LIMS profiles along their orbit tracks provide for better continuity and detail in map analyses of these two species on pressure surfaces. It is judged that the chemical effects of the oxides of nitrogen on ozone can be studied quantitatively throughout the stratosphere with the LIMS V6 data.

Global distributions of nitric acid from IASI/MetOP measurements

Abstract. This paper presents the first global distributions of HNO3 total columns acquired by the Infrared Atmospheric Sounding Interferometer (IASI) instrument, launched onboard the MetOp platform in October 2006. IASI is an infrared nadir-looking Fourier transform spectrometer providing atmospheric radiance spectra at 0.5 cm−1 spectral resolution, from which temperature and infrared absorbing gas concentration profiles are retrieved with global Earth coverage twice a day. A first analysis of the IASI measurements in terms of information content demonstrates the possibility of retrieving a total column for HNO3 at all latitudes with a maximal sensitivity in the middle stratosphere. The retrievals are performed from IASI spectra in the atmospheric window using a fast radiative transfer model and inversion software (FORLI) relying on the Optimal Estimation Method. The operational processing of HNO3 total columns is achieved since March 2008. We show that FORLI-HNO3 performs well at all latitudes (RMS of the spectral residuals around 2.3×10−6 W/m2 sr m−1) and provides HNO3 total columns with on average statistical errors of about 12%, reaching the threshold value of 32% at the equatorial belt. The global distributions of the retrieved total columns for one year (from March 2008 to February 2009) are presented and discussed with emphasis given to seasonal and interhemispheric variations. Local seasonal variations at 6 specific locations are also described and discussed in comparison with MLS volume mixing ratios at 46.5 hPa. The seasonal cycle observed in Polar regions is highlighted, with maxima observed in fall-winter and minima during spring-summer. The denitrification inside the Antarctic polar vortex during winter is clearly revealed with unprecedented horizontal resolution: HNO3 columns decreasing down to about 1×1016 molecules cm−2 are observed, which is consistent with the lower values of temperature observed between 50 and 15 hPa (~20–25 km) and the resulting formation and sedimentation of polar stratospheric clouds. During the same period, the collar region of high quantities of HNO3 at the vortex edge is also observed around 65–60° S latitude. Preliminary correlations between IASI derived HNO3 and O3 columns inside the polar vortex are presented and discussed.

Nitric acid in the stratosphere based on Odin observations from 2001 to 2009 – Part 1: A global climatology

Abstract. 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 were performed approximately on two observation days per week. An HNO3 climatology based on more than 7 years of observations from August 2001 to April 2009 covering the vertical range between typically ~19 and 45 km (~1.5–60 hPa or ~500–1800 K in terms of potential temperature) 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 large 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 over 7 years of UARS/MLS (Upper Atmosphere Research Satellite/Microwave Limb Sounder) measurements from the 1990s, shows 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 the better altitude resolution of Odin/SMR as well as the slightly different altitude ranges are considered. Odin/SMR reaches higher up and UARS/MLS lower down in the stratosphere. An overview from 1991 to 2009 of stratospheric nitric acid is provided (with a short gap between 1998 and 2001), if the global measurements of both experiments are taken together.

First global distributions of nitric acid in the troposphere and the stratosphere derived from infrared satellite measurements

Global distributions of nitric acid (HNO3) partial columns in the troposphere and the stratosphere are shown for the first time. HNO3 vertical profiles are retrieved from a set of high‐resolution infrared spectra, measured by the nadir‐viewing Interferometric Monitor for Greenhouse Gases (IMG) instrument onboard the ADEOS satellite. Ten successive days of IMG operation in April 1997 are analyzed, yielding quasi‐global distributions. We show that the IMG measurements contain between 0.7 and 1.8 independent pieces of information on the HNO3 vertical distribution; the extent of which depends on the observed scene. In the tropics and the midlatitudes, tropospheric and stratospheric columns can be separated, whereas, in the colder polar regions, the total column is the most relevant quantity. A detailed error budget reveals that the accuracy on the profile measurements ranges from 5–15% in the stratosphere to about 20–30% in the middle troposphere, and as much as 60% in the lowermost troposphere where the measurements are less sensitive. The global distributions of tropospheric and stratospheric partial columns are presented and discussed. In the stratosphere we measure higher columns at both poles than in the intertropical belt, as expected for the period in April analyzed here. In the troposphere, the zonal distributions show elevated values nearby NOx source regions, such as central Europe, the Eastern coast of the United States, and the North‐West of India. Typical profiles with mixing ratios up to 2 ppbv in the boundary layer and 1 ppbv in the free troposphere are identified. These novel results indicate a possible role of HNO3 in the long‐range transport of active nitrogen and open promising perspectives for future space missions dedicated to atmospheric chemistry.

Formation and Phase Distribution of Nitric Acid Hydrates in the Mole Fraction Range x(HNO3) &lt; 0.25: A Combined XRD and IR Study.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Update to the stratospheric nitric acid reference atmosphere

Observations of the global distribution of nitric acid (HNO 3) obtained by the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument on the Upper Atmospheric Research Satellite (UARS) have considerably extended our knowledge of its spatial and temporal distribution. The data span 16 months, and extend to 80 °S, within the Antarctic vortex during southern winter. The evaluation of the accuracy, precision, and resolution of these data are briefly described. The zonal mean distribution of nitric acid is characterized by a stratospheric layer with largest mixing ratios near 30 hPa in polar regions, sloping up to a slightly higher altitude but low mixing ratios in the tropics. New features are regions of very low nitric acid within the Antarctic vortex, and sensitivity to stratospheric aerosol concentration.

Polar stratospheric clouds due to vapor enhancement: HALOE observations of the Antarctic vortex in 1993

Aerosol measurements from the Halogen Occultation Experiment (HALOE) during the Antarctic spring of 1993 are compared with calculations of the volume of different types of polar stratospheric clouds (PSCs) at equilibrium. The observed volumes increased by a factor of ∼30 coincident with water vapor enhancements of ∼3 ppmv, suggesting that the enhancement of water vapor was important in determining PSC growth. The enhanced water vapor was coincident with increased methane mixing ratios, and trajectory analysis suggests that the vapor enhancements were consistent with transport from lower latitudes. The nitric acid distribution was not measured and is treated either as constant or as positively correlated with the observed water. Comparing the observed volumes with model calculations assuming constant nitric acid suggests that the PSCs were composed of liquid ternary H2SO4‐H2O‐HNO3 aerosols (LTA) rather than solid nitric acid trihydrate (NAT). However, if the water vapor intrusions were accompanied by enhanced nitric acid, the observations closely match predictions for solid NAT, and those for LTA. These comparisons highlight the importance of the vapor distributions for modeling PSC growth and suggest that vapor resupply is important for late spring PSC growth. This work also highlights some inherent limitations of large field of view limb‐viewing instruments for the observation of PSCs.

Revised reference model for nitric acid

A nearly global set of data on the nitric acid distribution was obtained for seven months by the Limb Infrared Monitor of the Stratosphere (LIMS) experiment on the Nimbus 7 spacecraft. The evaluation of the accuracy, precision and resolution of these data is described, and a description of the major features of the nitric acid distributions is presented. The sonal mean for nitric acid is distributed in a stratospheric layer that peaks near 30 mb, with the largest mixing ratios occurring in polar regions, especially in winter.

MODELLING OF NITRIC ACID AND WATER EXTRACTION FROMAQUEOUS SOLUTIONS CONTAINING A SALTING-OUT AGENT BY TRI-N-BUTYLPHOSPHATE

ABSTRACT A thermodynamic model is presented for nitric acid and water extraction equilibria by tri-n-butylphosphate (10, 30, 50 and 100 vol%) in dodecane from aqueous solutions containing nitric acid (0-14M) and in presence or not of a salting-out agent (lithium nitrate, ammonium nitrate). The activity coefficient of nitric acid was calculated from experimental data using MIKULIN's equation, and those of the components in the organic phase were calculated by SERGIEV SKI I-D ANNUS’ equation. A satisfactory description of the distribution of nitric acid and water is obtained in a wide range of acidity of the aqueous phase by taking into account the formation of the following complexes: TBP, TBPH2O, HNO3H2O,TBP HNO3,(TBP)2HNO3H2O,TBP.(HNO3)2

Study of Hydration and Ionization of Nitric Acid in Benzene

Abstract The hydration and ionization of nitric acid in benzene were examined at 298 K. The distribution of nitric acid and of water between aqueous solutions and benzene were determined as functions of water activity in the aqueous phase. Two hydrates, mono- and decahydrate, were found in addition to the anhydride in the organic phase by analyzing the distribution data on the basis of the stoichiometry of the acid hydration. The mono- and decahydrate were ascribed to molecular and ionized nitric acid, respectively, by means of spectrophotometry of the organic phase. By the analyses of the absorption spectra and the distribution data, the ionization of nitric acid by water in benzene was clarified and the equilibrium constant was determined.

Extraction of nitric acid with quaternary ammonium bases

Distribution of nitric acid between water or aqueous of ammonium nitrate and xylene solutions of tri- n-octylmethylammonium nitrate or Nivol/2-ethylhexanol solutions of Aliquat 336 nitrate has been studied. The extraction of nitric acid has been found to increase with increasing concentration of ammonium nitrate in the aqueous phase. A mathematical model of equilibrium which includes the non-ideality in both aqueous and organic phases as well as the influence of organic diluents has been formulated and its parameters evaluated. Two complexes, QABN.HNO 3 and QABN.2HNO 3, have been assumed to exist in the organic phase. Formation of the former has been found to be more easy in xylene than in Nivol/2-ethylhexanol, while formation of the latter has been found not to depend on the diluent.