High HNO3 Concentrations Research Articles

Raman spectra of nitric acid in aqueous sulfuric acid solutions

1. The relative concentrations of NO2+ ions have been calculated for low concentrations of nitric acid (0.1–0.3 M), using internal standards. 2. A procedure is proposed for the calculation of NO2+ ion concentrations in sulfuric acid-nitric acid-water systems with high concentrations of HNO3 in the system, and values have been calculated for the equilibrium concentrations of NO2+ in solutions containing up to 6.8 M nitric acid. 3. A single curve has been plotted for the ionization of nitric acid in aqueous sulfuric acid solutions; the correctness of the scheme that has been adopted for the ionization of nitric acid has been verified.

The effect of the nitric acid concentration on the kinetics of 2,4-dinitroaniline nitration in aqueous nitric and sulfuric acid solutions

1. The effective pseudo-monomolecular rate constant for the nitration of 2,4-dinitroaniline to 2,4,6-trinitroaniline in H2SO4+HNO3 mixtures varies with the nitric acid concentration, reaching a limiting value at high HNO3 concentrations. 2. The kinetic data on the nitration of 2,4-dinitroaniline have been used to calculate the equilibrium constant for the formation of nitramine, a reaction intermediate, the value so obtained agreeing with that arrived at from spectrophotometric measurements.

The kinetics of plutonium oxide dissolution in nitric/hydrofluoric acid mixtures

The dissolution rate of plutonium oxide powder in nitric/hydrofluoric acid mixtures is controlled by a chemical reaction at the PuO2 surface rather than by diffusion. The reaction is first order with respect to both the surface area (S) of PuO2 and the concentration of free (non-complexed) hydrofluoric acid ([HF]ƒ) in solution. As the dissolution progresses, the surface area decreases and free HF is consumed by complexation with dissolved Pu(IV) to form PuFx(4−x)+ complexes. This results in a rapid decrease of the dissolution rate with time. The initial rate is not affected by HNO3 concentration in the range of 4–12 M. However, at longer reaction times the rate increases with increasing HNO3 concentration. At higher HNO3 concentrations more free HF is available for reaction since plutonium fluoride complexes are less stable. Rate equations which describe changes in S and [HF]ƒ during dissolution are derived and rate constants are given for dissolution of PuO2 obtained by burning the metal. The second order rate constant is 3.0 × 10−6l/sec-m2 at 35°C for dissolution of this oxide.

Separation of Molybdenum-99 from Neutron-Irradiated Uranium-235 with Sulfur as Collector

Abstract The separation of 99Mo from other fission products has been successfully attempted by isolating S in a HNO3 solution of neutron-irradiated UO2 and collecting 99Mo on it. Influence of various factors on the separation of 99Mo was examined. When 5% aqueous solution of K2S was added to the solution of fission products of high HNO3 concentration and the mixture of S stood for 10 min, over 80% of the 99Mo could be separated with the precipitate. Besides 99Mo, 132Te, 103Ru and other nuclides also accompanied the precipitate. The presence of Mo carrier and U affected greatly the separation of 99Mo, but that of Zr or Te carrier did not.

Graft Copolymerization of Methyl Methacrylate onto Starch and Triethylamino Starch

The effects of polymerization conditions were investigated on the graft copolymerization of methyl methacrylate (MMA) initiated by ceric ammonium nitrate on starch and triethylamino starch (TEAS) in aqueous medja.Under the conditions such as starch or TEAS concentration of 2 %, HNO3 concentration of 0.014 N, polymerization temperature of 50°C and reaction time of 2 hrs., the total conversion (T), the percentage of grafting (P) and the graft efficiency (E) became higher with increasing initiator concentration and lower with increasing monomer concentration (4∼17 %).The polymerization temperature (30∼60°C) appeared to be most suitable at 50°C from the results of (P). On the polymerization time, (T) and (P) became higher with increasing the time. (P) and (E) showed maximum values at some concentration of starch or TEAS respectively, and similarly with HNO3 concentration also. The value of (P) became larger at the region of high HNO3 concentration with low concentration of initiator, whereas in the case of low concentration of HNO3 with high concentration of initiator.(P) and (E) of the aqueous suspension system of starch or TEAS were generally higher than that of the aqueous solution system, and the results of the starch system were larger than that of the TEAS system.The graft copolymer was quite insoluble in boiling water, methanol and acetone, but dissolved in dimethylsulfoxide. Therefore, the cross-linked structure seemes to be absent in this copolymer.