In nitric acid solutions

F. J. Miner and P. G. Hagan, Pate oJHjdrogen Peroxide Decomposition in Nitric Acid Solutions, Dow Chemical USA, Golden, Colo. 

Fig. 2.21 Safe operating conditions for various steels in nitric acid solutions. Isocorrosion lines at 0-1 g irT h" ...

Fig. 3.27 Corrosion rates of various stainless steels in nitric acid solutions at boiling point...

Procedure. The solution should not exceed 50 mL in volume, all metallic elements should be present as nitrates, and the cerium content should not exceed 0.10g. Treat the solution with half its volume of concentrated nitric acid, and add 0.5 g potassium bromate (to oxidise the cerium). When the latter has dissolved, add ten to fifteen times the theoretical quantity of potassium iodate in nitric acid solution (see Note) slowly and with constant stirring, and allow the precipitated cerium(IV) iodate to settle. When cold, filter the precipitate through a fine filter paper (e.g. Whatman No. 42 or 542), allow to drain, rinse once, and then wash back into the beaker in which precipitation took place by means of a solution containing 0.8 g potassium iodate and 5 mL concentrated nitric acid in 100 mL. Mix thoroughly, collect the precipitate on the same paper, drain, wash back into the beaker with hot water, boil, and treat at once with concentrated nitric acid dropwise until the precipitate just dissolves (20-25 mL... 

The vast majority of the studies on the reactions such as 5-12 have been the classical type in acidic solutions, predominantly in nitric acid solutions for obvious process related interests. The results of such studies have been summarized by Newton (4) so only a very brief recapitulation is warranted. 

The vast amount of work carried out in nitric acid solutions can not be adequately summarized. Suffice it to say results in these solutions are plagued with irreproducibiliy and induction periods, but the general pattern is reduction of Pu(VI). 

Dissolution. Plutonium is solubilized in nitric acid solutions at Rocky Flats. The feed material consists of oxide, metal and glass, dissolution heels, incinerator ash and sand, slag, and crucible from reduction operations. The residues are contacted with 12M HNO3 containing CaF2 or HF to hasten dissolution. Following dissolution, aluminum nitrate is added to these solutions to complex the excess fluoride ion. 

Previously, Bruno and Santoro had found complete exchange occurred between the ions Ag(dipy)2 or Ag(phen)2 and Ag, in nitric acid solution, within the separation time. 

Fig. 5.54 Mixed potential. (A) Zinc dissolution in acid medium. The partial processes are indicated at the corresponding voltammograms. (B) Dissolution of mercury in nitric acid solution. The original dissolution rate characterized by (1) the corrosion current y a is enhanced by (2) stirring which causes an...

Alloxan crystallizes from solution much more slowly when it is nearly free of nitric acid and when other soluble substances are present it is, however, less soluble in nitric acid solution than in water. 

Most of the other elements are determined by the methods of inorganic analysis after organic material has been oxidised in nitric acid solution by the Carius procedure. 

When methylnitrolic acid is heated in nitric acid solution it decomposes into nitrous and fulminic acids. The latter can be isolated as silver fulminate if silver nitrate is present. 

Thus, ammonium thiocyanate reacts with silver nitrate in nitric acid solution as below ... 

Fig. 11-14. (a) Corrosion rate of metallic iron in nitric acid solution as a function of concentration of nitric add and (b) schematic polarization curves for mixed electrode reaction of a corroding iron in nitric add W p, = iron corrosion rate CHNO3 = concentration of nitric add t" (t ) = current of anodic iron dissolution (cathodic nitric add reduction) dashed curve 1= cathodic current of reduction of nitric add in dilute solution dashed ciuve 2 s cathodic current of reduction of nitric add in concentrated solution. [From Tomashov, 1966 for (a).]... 

For the rapid determination of Tc in a mixture of uranium fission products. Love and Greendale have used the method of amalgam polarography. It consists in a selective reduction of technetium at a dropping mercury electrode at a potential of —1.55 V vs. SCE in a medium of 1 M sodium citrate and 0.1 M NaOH. Under these conditions, technetium is reduced to an oxidation state which is soluble in mercury. The amalgam is removed from the solution of fission fragments and the amount of Tc determined in nitric acid solution of the amalgam by a y count. For Tc the measurement accuracy is within 1 %, and the decontamination factor from other fission products 10 . 

Zhang, Y. and Muhammed, M. Solubility of calcium sulfate dihydrate in nitric acid solutions containing calcium nitrate and phosphoric acid, J. Chem. Eng. Data, 34(1) 121-124, 1989. 

Procedure. Weigh 2 g of the oven dried sample ground to 1 mm into a porcelain or glass crucible and place in a cool muffle furnace. Increase the temperature to 550°C and ash for 2 h. Cool and dissolve in nitric acid solution, make up to 20 ml and store in a polythene capped tube. Allow to settle before transferring to another clean sample tube by decanting or using a polythene Pasteur pipette. Analyse the solution by AAS or ICP according to the manufacturer s recommendations. 

Elemental composition Mo 36.34%, C 27.30%, 0 36.36%. A benzene solution of the hexacarbonyl may be analyzed by GC/MS. Molybdenum metal digested in nitric acid solution may be analyzed by various instrumental techniques. Also, the compound may be thermally dissociated and the liberated CO may be identified by GC using a TCD or by GC/MS using an appropriate capillary column. 

RUO2X H2O in nitric acid solution. This process has potential application in nuclear fuel reprocessing [426]. 

The technique of differential pulse stripping voltammetry has been developed for the determination of plutonium in nitric acid solutions [117]. The successful determination of plutonium was demonstrated... 

Reports are given of explosions occurring when Ti test specimens were used in red fuming nitric acid. The cause of such explosions is unknown. The use of Zr in nitric acid solutions is described briefly Ref J.A. English et al, Corrosion 12, 658 (1956) CA 50, 9988 (1956)... 

Although a single value is given in Table 16 for Ee (Ce3+(aq)/Ce4+(aq)), the oxidation potential of Ce3+ ion in aqueous media varies considerably with the nature of the counterion, doubtless due to stabilization of Ce4+ to different extents by complexation. Thus in 1M H2S04, Ee= 1.4435 V,680 but in perchloric acid solutions, = 1.6400-1.7310 V depending on concentation,681 while a range of 1.6085-1.6104 V was observed in nitric acid solutions.682 There is some evidence for the formation of polymeric species in aqueous nitric acid solutions, and this may explain some anomalies in electrode potential determinations. Values for association constants of 17 and 2 respectively for Ce4+-Ce4+ and Ce4+-Ce3+ interactions were obtained.683... 

M. N. Myers, Absorption Spectra of Plutonium and Impurity Ions in Nitric Acid Solution, HW-44744, General Electric Co., 1956. 

Meguro, Y. Iso, S. Takeishi, H. Yoshida, Z. Extraction of uranium(VI) in nitric acid solution with supercritical carbon dioxide fluid containing tributylphosphate, Radiochim. Acta 75 (1996) 185-191. 

Loading the sample in nitric acid solution, the tetravalent actinides are strongly retained along with hexavalent uranium. However, trivalent actinides like Am(III) and Pu(III) are not retained from nitric acid solutions (unlike TRU-Resin). Pu retained as Pu(IV) can be removed from the column by reducing it to Pu(III). Tetravalent actinides and U(VI) are also retained in strong hydrochloric acid solution, with retention sharply dropping off as hydrochloric acid concentrations decrease (see Figure 9.12). Th(IV) is less retained in hydrochloric acid solutions than U(VI). Actinides retained on UTEVA-Resin from nitric acid solutions can be released with diluted nitric acid or low hydrochloric acid concentrations. 

Although the specific decomposition rate is much lower in nitric acid solution the decomposition still follows the first order law because the number of simple molecules which decompose is always proportional to the total concentration of nitrogen pentoxide at any time, and this is the criterion of a unimolecular reaction. 

N204 in nitric acid solutions dissociated in the same way, as Goulden and Millen [47] found, when examining Raman spectra of such solutions. 

The substitution of a primary amino group by a nitro group generally occurs by diazotization and the Sandmeyer reaction. ( Komer and Contardi reaction ) [222], In certain cases, diazonium salt nitrates, when boiled in aqueous solution, are converted to nitrophenols. For example p-toluidine, when diazotized in nitric acid solution, forms nitro-p-cresol after the solution had been brought to the boil (Nolting and E. Wild [203a]) ... 

Solvent-degrease in nitric acid solution as in item 5 ASTM D 2651 nitric acid-sodium chlorite etch,... 

The extraction of Bk(III) by phosphoorganic acids has been studied, and activity coefficients for Bk(III) in nitric acid solution were estimated (204). In addition, a mechanism for the extraction of Bk(IV) by hydrogen di(2-ethylhexyl)orthophosphoric acid (HDEHP) from nitric acid solutions was proposed. 

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