Isotope Effect of Cation Electromigration in Molten Lithium Chloride-Nitrate-Mixtures

1975 ◽  
Vol 30 (1) ◽  
pp. 75-78 ◽  
Author(s):  
Vladislav Ljubimov ◽  
Arnold Lundén
Keyword(s):  
Isotope Effect ◽  
Lithium Chloride ◽  
Isotope Effects ◽  
Mass Effect ◽  
Relative Difference ◽  
Lithium Ions ◽  
Lithium Isotopes ◽  
Decomposition Products ◽  
Molten Lithium

Abstract Molten mixtures of lithium chloride and nitrate, including the decomposition products nitrite and oxide, were electrolysed at about 600 °C with gaseous electrodes. The relative mobilities of the lithium isotopes were studied. The mass effect (relative difference in mobility divided by relative difference in mass) is 0.063 for a mixture with 20% Cl- and 0.069 for 80% CI-, which both are more than 30% smaller than those interpolated from the isotope effects of pure LiNO3 and LiCl. It is concluded that the lithium ions interact more strongly (with the anions and/or with each other) in a melt containing several anions than in a pure melt. The experiments also yield some information about the mobilities of the anions present in the melt.

Isotope Effects of Electromigration in Molten Lithium-Potassium Sulfate Mixtures

1968 ◽  
Vol 23 (10) ◽  
pp. 1558-1562 ◽  
Author(s):  
Arnold Lundén ◽  
Vladislav Ljubimov
Keyword(s):  
Transport Mechanism ◽  
Isotope Effects ◽  
Mass Effect ◽  
Relative Difference ◽  
Potassium Sulfate ◽  
Mass Effects ◽  
Low Concentrations ◽  
Eutectic Concentration ◽  
Molten Lithium ◽  
The Difference

The difference in mobility of the isotopes of lithium and potassium has been studied in molten sulfate mixtures over the concentration range 41 to 90 equiv. % Li2SO4. For the eutectic composition (80% Li2SO4) the temperature range 625 to 835°C was covered. The mass effect, μ, (relative difference in mobility divided by relative difference in mass) was calculated. The accuracy, which is much lower for potassium than for lithium, was not sufficient to provide information on the temperature dependence of the mass effects, but it was evident that the ratio between the mass effects of the two cations depends upon concentration. Thus, while the mass effect for lithium is — 0.13 ± 0.02 over the whole range, for potassium it is of the order of — 0.16 for the eutectic concentration and — 0.07 for the mixture with 41% Li2So4. The observed increase of the mass effect at low concentrations is in agreement with results for other systems and can be expected from simple models of the transport mechanism. For lithium the mass effect is the same in the molten sulfate mixtures as in pure fcc lithium sulfate.

The Temperature Dependence of the Isotope Effect for Electromigration of Lithium Ions in Molten Lithium Nitrate

1969 ◽  
Vol 24 (6) ◽  
pp. 892-900 ◽  
Author(s):  
Arnold Lundén ◽  
Alf Ekhed
Keyword(s):  
Standard Deviation ◽  
Melting Point ◽  
Mass Effect ◽  
Relative Difference ◽  
Lithium Nitrate ◽  
Lithium Ions ◽  
Alkali Ions ◽  
Cooperative Motion ◽  
Molten Lithium ◽  
Experimental Values

The relative difference (Δb/b) between the internal electromigration mobilities of 6Li and 7Li in molten LiNO3 has been measured over the range 313° to 488 0C. The mass effect,μ =(Δb/b) /(Δm/m), is found to be μ = 0.0845+ (0.00002 ±0.00002) (t-300) where t is the temperature in °C and the quoted error is the standard deviation. There is thus in this case no significant influence of the temperature upon the mass effect. Some previous investiga­tions of molten LiNO3 gave smaller values for the mass effect. The reasons for these apparent dis­crepancies are discussed. A slight, but significant, anomalous enrichment of the light isotope is ob­tained in the middle of the cell, as has been previously observed in experiments with KNO3 . The mass effects have now been measured for all five alkali ions in the pure molten nitrates. For a corresponding temperature chosen 5% above the melting point none of the experimental values differ more than 14% from the relation μ+ =-0.0848 (1+m +/46) -1.The obtained relations are interpreted in terms of cooperative motion of the ions in a molten salt.

scholarly journals The Isotope Effect for Electromigration of Sodium Ions in Molten Sodium Nitrate

1972 ◽  
Vol 27 (2) ◽  
pp. 288-293
Author(s):  
Nobufusa Saito ◽  
Katsumi Hirano ◽  
Kohei Okuyama ◽  
Isao Okada
Keyword(s):  
Melting Point ◽  
Isotope Effect ◽  
Sodium Nitrate ◽  
Mass Effect ◽  
Relative Difference ◽  
Internal Mass ◽  
Sodium Ions ◽  
Molten Sodium

AbstractThe relative difference (Δb/b) between the internal electromigration mobilities of 22Na and 24Na in molten NaNO3 has been measured in the range 340 - 515 °C. The internal mass effect, μint= (Δb/b)/(Δm/m) is - 0.056 at 340 °C (melting point 308 °C), - 0.079 at 435 °C and - 0.068 at 515 °C. The errors in μint are ±0.002.

scholarly journals The Temperature Dependence of the Isotope Effect for Electromigration of Potassium Ions in Molten Potassium Nitrate

1968 ◽  
Vol 23 (11) ◽  
pp. 1779-1782
Author(s):  
Arnold Lundén ◽  
Alf Ekhed
Keyword(s):  
Thermal Decomposition ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Separation Factor ◽  
Mass Effect ◽  
Potassium Nitrate ◽  
Relative Difference ◽  
Potassium Ions ◽  
Heavy Isotope ◽  
Significant Enrichment

The relative difference (Δb/b) between the electromigration mobilities of 39K and 41K in molten KNO3 has been measured over the range 354° to 586°C. The mass effect, μ= (Δb/b)/(Δm/m), becomes larger when the temperature is increased, following the relation—,u =0.0385+0.000124 (t-337)where t is the temperature in °C. Due to thermal decomposition, the nitrate is partly converted to nitrite, but it is proved by performing experiments with different initial concentrations of nitrite, that the isotope effect for potassium is not influenced noticeably by the concentration of the anions.The experiment is designed to give an enrichment of the heavy isotope 41K in a small anode compartment and in the upper part of the separation tube. However, it was possible to establish that a slight, but significant, enrichment of the light isotope 39K was obtained in the lower part of the separation tube, i. e. just above the opening into the large cathode compartment. A separation factor of 1.003 was estimated for this enrichment effect, which is due to non-ideal conditions of the experiment.

The Isotope Effect of Electromigration in Some Solid Alkali Halides

1971 ◽  
Vol 26 (2) ◽  
pp. 300-307 ◽  
Author(s):  
Takeshi Morimoto ◽  
Isao Okada ◽  
Nobufusa Saito
Keyword(s):  
Activation Energy ◽  
Ionic Conductivity ◽  
Single Crystal ◽  
Potassium Chloride ◽  
Isotope Effect ◽  
Lithium Fluoride ◽  
Alkali Halides ◽  
Mass Effect ◽  
Relative Difference ◽  
Solid Alkali Halides

The isotope effect of electromigration in some solid alkali halides was determined in their intrinsic ionic conductivity region. The external cationic mass effect (i. e., relative difference in cationic mobility/relative difference in mass) of lithium fluoride, chloride, bromide and iodide and potassium chloride was -0.243, -0.207, -0.195, -0.190 and -0.254, respectively, at 750, 540, 470, 370 and 600 °C, respectively. No difference of the mass effect was found between polycrystalline and single crystal potassium chloride. When the available data for the mass effect of the solid salts are plotted against the activation energy for electric conductance, there is a tendency for the mass effect to increase as the activation energy increases.

Electromigration in Molten and Solid Binary Sulfate Mixtures: Relative Cation Mobilities and Transport Numbers

1966 ◽  
Vol 21 (10) ◽  
pp. 1592-1600 ◽  
Author(s):  
Vladislav Ljubimov ◽  
Arnold Lundén
Keyword(s):  
Melting Point ◽  
Eutectic Composition ◽  
Isotope Effects ◽  
Mass Effect ◽  
Cation Transport ◽  
Relative Difference ◽  
The Other ◽  
Transport Numbers ◽  
Li Ion ◽  
The Difference

The electrolytic displacement of the two cations relative to each other has been studied in solid (Li, Ag)2SO4 (93 eq. % Li) at 700 °C, solid (Li, K)2SO4 (91% Li) at 575 °C and molten (Li, K)2SO4 (41 — 90% Li). For melts containing more than about 52% Li the Li ions have a higher mobility (at about 740 °C) than the K ions, while the latter have the highest mobility in mixtures where K is the more abundant cation. The relative difference (Δb/b) between the mobilities of the two cations exceeds 15% already at concentrations some 8% off from the equimobility concentration. For the eutectic composition, 80% Li, Δb/b was about 60% independent of the temperature (590 — 835 °C). For mixtures containing 90% Li it was established that Δb/b changes its sign at the melting point. Thus, the mobility of the Li ion was of the order of half the mobility of the other ion in the solid systems, while it was about twice as large in the melt. The cation transport numbers (relative to the anion) were calculated for all experiments ,and for the melts also the difference between the cation mobilities. An estimation is made of the obtainable accuracy of electromigration experiments.The experiments with melts were analysed for isotope effects. The light isotopes were always enriched towards the cathode, independent of whether Li or K had the higher mobility. The magnitude of the isotope effects shows a concentration dependence, i. e. the mass effect (relative difference in mobility divided by relative difference in mass) tends to increase when an ion is dilute, as previously found for other systems. Thus for the melts with 80% Li, the mass effect is higher for K than for Li.

Cation Mobilities, Including Isotope Effects, for Electromigration in Molten Mixtures of Potassium and Rubidium Nitrate

1979 ◽  
Vol 34 (10) ◽  
pp. 1207-1211 ◽  
Author(s):  
Alf Ekhed ◽  
Dr. Arnold Lundén
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Isotope Effects ◽  
Mass Effect ◽  
Potassium Ions ◽  
Rubidium Nitrate ◽  
Mole Percent ◽  
The Difference

Abstract Electromigration of cations has been studied in molten KNO3 -RbNO 3 mixtures as a function of concentration (11 -94 mole % RbNO3 , about 380 °C) and temperature (about 10 mole % RbNO3 , 378 -560 °C). The mobility of K+ is slightly larger than that of Rb+ at all concentrations, the difference being about 3% in KNO3 -rich and 2% in RbNO3 -rich mictures. Neither for potassium nor for rubidium is the isotope effected affected much by the composition of the melt, although there is a tendency that the isotope effect for rubidium is somewhat larger in mixtures than in pure salts. Both isotope effects have the same temperature dependence in the investigated mixture as in the pure salts. The isotope effects for potassium and rubidium have also been determined for ternary NaNO3 -KNO3 -RbNO3 mixtures containing about 5 mole percent of NaNO3 and of RbNO3 . For comparison, a study of the mass effect for potassium ions in NaNO3 -KNO3 is also reported.

The Temperature Dependence of the Isotope Effect for Electromigration of Rubidium Ions in Molten Rubidium Nitrate

1972 ◽  
Vol 27 (7) ◽  
pp. 1135-1138
Author(s):  
Arnold Lundén ◽  
Allan Floberg ◽  
Ronny Mattsson
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Mass Effect ◽  
Relative Difference ◽  
Rubidium Nitrate ◽  
Similar Temperature Dependence ◽  
Similar Temperature

Abstract The relative difference (Δb/b) between the internal electromigration mobilities of 85Rb and 87Rb in molten RbNO3 has been measured over the range 355 to 500 °C. The mass effect μ = (Δb/b)/(Δm/m) has a complicated temperature dependence. Thus, the largest mass effect, -μ=0.061, was obtained at 445 °C, while it is about 0.033 at 350 °C and 0.041 at 500 °C. A similar temperature dependence was found by SAITO et al. for μNa in pure NaNO3, and for both μRb and μNa maxima have been found also in nitrate mixtures (in KNO3-RbNO3 and NaNO3-KNO3)

scholarly journals Nitrogen isotope effects can be used to diagnose N transformations in wastewater anammox systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paul M. Magyar ◽  
Damian Hausherr ◽  
Robert Niederdorfer ◽  
Nicolas Stöcklin ◽  
Jing Wei ◽  
...  
Keyword(s):  
Isotope Effect ◽  
Isotope Composition ◽  
Isotope Effects ◽  
Nitrogen Isotope ◽  
Anammox Bacteria ◽  
Ammonium Oxidation ◽  
Experimental Conditions ◽  
N Transformations ◽  
Natural Systems ◽  
Inverse Isotope Effect

AbstractAnaerobic ammonium oxidation (anammox) plays an important role in aquatic systems as a sink of bioavailable nitrogen (N), and in engineered processes by removing ammonium from wastewater. The isotope effects anammox imparts in the N isotope signatures (15N/14N) of ammonium, nitrite, and nitrate can be used to estimate its role in environmental settings, to describe physiological and ecological variations in the anammox process, and possibly to optimize anammox-based wastewater treatment. We measured the stable N-isotope composition of ammonium, nitrite, and nitrate in wastewater cultivations of anammox bacteria. We find that the N isotope enrichment factor 15ε for the reduction of nitrite to N2 is consistent across all experimental conditions (13.5‰ ± 3.7‰), suggesting it reflects the composition of the anammox bacteria community. Values of 15ε for the oxidation of nitrite to nitrate (inverse isotope effect, − 16 to − 43‰) and for the reduction of ammonium to N2 (normal isotope effect, 19–32‰) are more variable, and likely controlled by experimental conditions. We argue that the variations in the isotope effects can be tied to the metabolism and physiology of anammox bacteria, and that the broad range of isotope effects observed for anammox introduces complications for analyzing N-isotope mass balances in natural systems.

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