Sodium impurities

The high-chromium casting alloys (50% nickel, 50% chromium and 40% nickel, 60% chromium) are designated for use at temperatures up to 900 C in furnaces and boilers Ared by fuels containing vanadium, sulfur and sodium compounds (e.g., residual petroleum products). Alloys with lower chromium contents cannot be used with residual fuel oils at temperature above 6S0 C because the nickel reacts with the vanadium, sulfur and sodium -impurities to form compounds that are molten above 650 C [27]. 

Lithium metal is produced commercially by electrolysis of a fused eutectic mixture of hthium chloride-potassium chloride (45% LiCl) at 400 to 450°C. The eutectic mixture melts at 352°C in comparison to the pure LiCl melting at 606°C. Also, the eutectic melt is a superior electrolyte to LiCl melt. (Landolt, P.E. and C. A. Hampel. 1968. Lithium. In Encyclopedia of Chemical Elements.C. A. Hampel, Ed. Reinhold Book Corp. New York.) Electrolysis is carried out using graphite anodes and steel cathodes. Any sodium impurity in hthium chloride may be removed by vaporizing sodium under vacuum at elevated temperatures. All commercial processes nowadays are based on electrolytic recovery of the metal. Chemical reduction processes do not yield high purity-grade metal. Lithium can be stored indefinitely under airtight conditions. It usually is stored under mineral oil in metal drums. 

The pre-mixed methane/argon mixture consisted of 1.2% methane and 98.8% argon, both being 99.99% Matheson research grade. Argon/ oxygen and zero air were used as oxidants. Prior to each run the driven section was evacuated with an oil difiFusion pump. Tests were conducted in shock-heated argon to determine possible interference from sodium impurities however, no ionization was detected. 

The nature of the lithium surface is important. Varying the particle size of the lithium dispersion from 25 pm with a surface area of 2782 cm to 150 pm with a surface area of 464 cm reduced the optical purity of the resulting acid by nearly 50%. It was also demonstrated that the amount of sodium impurity in the lithium dispersion had a significant effect not only on the stereochemical results of the metallation reaction but also on the reactivity of the metal surface itself. For example, reaction of chiral l-iodo-2,2-diphenylcyclopropane with 25 pm lithium dispersions containing 0.002 %, 0.02 % and 1 % sodium yielded after carbonation l-methyl-2-cyclopropanecarboxylic acid (99) with optical purities of 13 %, 16% and 36%, respectively. The increase in optical purity with increase in sodium content may be a consequence of lowering the ionization potential of the metallic surface . ... 

This method however cannot remove the sodium impurity which disturbs the red colour of the flame. Strontium carbonate of high purity is obtained when ammonium carbonate is added to strontium nitrate solution to precipitate it. If Ca or Ba is present in the solution, it precipitates at the same time and the separation from the strontium carbonate is difficult. 

Data available on the first failure did not permit an estimate of the water leak rate. For the second leak, however, sufficient data were available to permit an estimate of the leakage rate during the final heat-transfer run. Estimates of this leakage rate were made from data both on the pressure rise and on the increase in sodium impurity content. These estimates indicated an average leak rate of approximately 0.01 pound per minute. 

This band is also reduced in intensity after doping with potassium (287) or in the presence of sodium impurities (169,288). For samples doped with high concentrations of Na, the bands at 3790 and 3770 cm are both absent, and the most intense band is observed at about 3742 cm (289,290). The deposition of phosphate species on the surface also seems to selectively ehminate the band at 3770 cm (291), whereas the deposition of sihcate species does not (286). The band also seems to disappear, at least partially, upon phase transition to 5-AI2O3 (204) or to 0-AI2O3 (257) and... 

INCREASE OF THE PRIMARY SODIUM IMPURITIES LEADING TO AN OVERSHOOT ON THE RANGE AUTHORISED BY THE OPERATING SPECIFICATIONS... 

Residual radioactivity. As it was pointed out in [7.4], the amount of the long lived radioactivity generated in sodium by neutrons is negligible. Activation of sodium reaches equilibrium state in about ten years of the first cycle of its use and will never exceed this level. The long-lived radionuclides furnished by fission products, sodium impurities and corrosion activation products are chemical elements alien to sodium, that makes possible its external contamination at the reactor plant decommissioning stage. 

It is essential for steady and safe operation of a sodium cooled fast reactor to limit the coolant and cover gas impurities to prevent corrosion of reactor component materials and to reduce radiation dose by corrosion products (CPs). Therefore, impurity concentrations of both coolant sodium and cover gas argon were measured during the duty cycle operation and annual inspection period. The sodium impurity data include oxygen, hydrogen, nitrogen, chloride, tritium, metal elements and radioactive ° Ag, Na, Xs. The cover gas impurity data include O2, N2, CO, CO2, H2, CH4, He, H and radioactive xenon and krypton isotopes. 

These data were measured by chemical analysis, gas chromatography, beta-ray scintillation and gamma-ray spectrometry. The sodium impurity concentrations were also determined by the sodium temperature in the plugging indicator. As an example, the trend of oxygen and hydrogen in the primary sodium are shown in Fig. 11. 

It must be ranembered that a little bit of sodium goes a long way in affecting flame color, due to the fact that sodium is an atomic, rather than a molecule emitter. A molecular emitter must form in the flame via a reaction between two chemical species. An atomic emitter requires no such flame chemistry to vaporize the atomic material, and it is ready to emit its atomic spectrum immediately upon vaporization in the pyrotechnic flame. A low percentage of a sodium impurity in a chemical can cause that chemical to affect flame color efforts to a significant extent, so quality control of raw materials is important when the production of a pure color is the goal. 

Investigation of the efficiency of systems for the monitoring and control of sodium impurities. 

In combustion environments sodium impurities are very common. These can lead to highly corrosive salt deposits. An example is ingested NaCl in combustion air, which reacts with sulfur impurities in the fuel to form highly stable Na2S04 (Jacobson, 1989) ... 

Mohammed Saad, A.B., Ivanov, V.A., Lavalley, J.C., Nortier, R, and Luck, F. Comparative study of the effects of sodium impurity and amorphisation on the Lewis acidity of y-alumina, Catal A Gen. 1993, 94, 71-83. 

Aqueous solutions of the metal salts, usually nitrates or sulfates, are precipitated with an alkali such as sodium carbonate. Ammonium carbonate ean be used to avoid residual sodium impurity, but it is relatively expensive. Occasionally precipitation conditions are controlled to form complex catalyst precursors and higher-activity products. If necessary, any support material can be added as a powder before the alkali is added. 

---