- Email: [email protected]
Dissolution of refractory plutonium dioxide
1470
Notes
The approximate coordinates of the uranium atoms could then be determined. The best fit was obtained with the following parameters in space group P21 :
x
y
z
0'98
0
0
0.33
0"97
0"65
0.67
0.99
0.34
0.17
0.23
0.79
0.67
0.26
0-87
The structure consists of pseudo-hexagonal layers at y = 0 and ½ with U-U-distances of 3.9 A. These layers are separated by sets of almost linear chains at y = ¼ and 3, parallel to the c-axis, at distances of 5"17 A from one another. A complete structure determination, based on X-ray and neutron diffraction data, is in progress and will be published in the near future.
Acknowledgement The author wishes to t h a n k Dr. E. H. P. CORDVUNKE for his stimulating interest and for providing the samples. P. C. DEBETS Reactor Centrum Nederland Petten, The Netherlands I. Inorg. Nucl. Chem.. 1964,Vol. 26, pp. 1470to 1471. PergamonPress Ltd. Printed in Northern Ireland Dissolution of refractory plutonium dioxide
(Received 19 February 1964; in revised form 27 March 1964) REFRACTORY plutonium dioxide dissolves only very slowly and incompletely in the more common mineral acids. BJORKLUNDTM found that the higher the temperature of preparation of the oxide, the more insoluble it was in potassium iodide-hydrochloric acid solution; correlation of this behaviour with X-ray diffraction and refractive index data led him to attribute the lower reactivity of the hightemperature oxide to the formation of a more perfect crystal lattice. Although potassium iodide-hydrochloric acid is partially effective for dissolving refractory oxide, the rate is low at room temperature and heating is not practical due to the evolution of iodine. Likewise, heating of commercial hydroiodic acid, which is stabilized with hypophosphorus acid, is not safe due to the release of phosphine, which can ignite spontaneously in air. Among the hydrohalic acids, hydrobromic acid ranks second to hydroiodic acid in acid strength and as a reducing agent; both of these properties should contribute to its performance in plutonium oxide dissolution. Furthermore, hydrobromic acid solutions may be boiled for long periods without excessive decomposition. Attention was therefore directed toward this acid as a possible solvent for plutonium dioxide. High-temperature plutonium dioxide was prepared by burning plutonium metal in air. For purposes of comparison, 10-g portions of this oxide were treated with 100 ml of boiling 16 M nitric, 12 M hydrochloric, and 9 M hydrobromic acids for 1 hr in covered beakers, after which each solution was diluted to 150 ml, filtered, and analysed for plutonium content. The results are given in Table l. TABLE I.--DISSOLUTION OF HIGH-TEMPERATUREPLUTONIUM DIOXIDE IN VARIOUS ACIDS Acid
Pu conc. g/l
PuO2 ( ~ ) Dissolved after 1 hr
HNO8 HC1 I-/Br
0.147 0.433 5.53
0.25 0.74 9.4
tl) C. W. BJORKLUND, USAEC Report LA-1869 (1954).
Notes
1471
The most commonly employed procedure for the dissolution of plutonium oxide involves extended reftuxing in concentrated nitric acid containing approximately 0.25 M fluoride ion. Frequently, however, insoluble oxide residues remain even after repeated treatment by this procedure. Because of the encouraging results obtained with hydrobromic acid, a programme was undertaken to dissolve a large quantity of these oxide residues in this acid. The procedure involved refluxing 500 g of the oxide in 1 1. of 9 M hydrobromic acid for 6-8 hr, followed by filtration. The solid residue was combined with 300 g of fresh oxide, refluxed in 9 M hydrobromic acid for 6-8 hr, and filtered as before. The filtrates were made basic with sodium hydroxide solution; the plutonium hydroxide precipitate was removed by filtration (the hydroxide filtrates being discarded), washed with water, and dissolved by adding it slowly to boiling nitric acid. Continued boiling for about 15 min efficiently expelled any residual bromine remaining in the solution. To minimize corrosion due to hydrobromic acid, the off-gases from both the reflux and boil-off operations were scrubbed with sodium hvdroxide solution. By continued repetition of the procedure, a quantity of oxide containing more than 3000 g of plutonium (as determined by sodium pyrosulfate fusion followed by radiometric assay) was dissolved, leaving a final residue containing less than 0.5 g of plutonium-a yield of greater than 99.98 percent. The plutonium content of the hydrobromic acid solutions after refluxing for 6 8 hr was 200 250 g L for those runs in which fresh oxide was added and for several runs after addition of fresh oxide ceased. (It was not considered desirable to attempt to obtain higher concentrations of plutonmm because of the possible crystallization of PuBr3 from the solution.) Finally, as the oxide became depleted, the concentration of the reflux solution decreased, generally by a factor of approximately two with each successive run. Treatment was discontinued when the plutonium concentration in the reflux solution became less than 1 g/l., although in most cases it would probably be more practical to stop before such a low concentration was reached. J. M. CLFVEt X~,D The Dow Chemical Comtoan)' Rocky Flats Diviffon Post Office Box 888 Gohlen, Colorado Since the elevation of this laboratory is 6000 ft, the boiling point of the nitric acid inixmre is lower (112 ° 114C, as compared to 120°-125°C at sea level), and thus the dissolution conditions are less rigorous than would exist if the operation were performed at sea level. This effect is considered to be minor, however.
J. Inorg. NucI. Chem., 1964. WoI.26, pp. 1471 to 1472. PergamonPress Ltd. Printed in Northern Ireland
Trimethylamine oxide complexes of non-transition metal halides (Received 13 February 1964)
RI=CENTLY complexes of transition metal compounds with trimethylalnine oxide (TMO) '~' and pyridine-N-oxide t~,2~ have been reported, but the only compounds of TMO with non-transition metal halides mentioned are TMO.BF~, ~3~ TMO.BCIs, TM 2TMO.SiFa, ~5~ 4TMO.SiCI~, ~:'~ and Ct' K. ISSLIEBand A. KREmICH, Z. anorff. Chem. 313, 338 (1961). !'zt j. V. QUAGt.IANO, J. FUJITA, G. FRANZ, D. J. PHILLIPS, J. A. WALMSLEYand S. Y. TYREI-:,J. Amer~ Chem. Soc. 83, 3770 (1961); R. L. CARHN, J. Amer. Chem. Soc. 83, 3773 (1961); S. KIDA, J. V. QUAGUANO, J. A. WALMSLEY and S. Y. TYREE, SDectrochbn. Acta 19, 189 (1963); Y. KAK~I;II, S. K~OA and J. V. QCrAGLIANO, Spectrochim. Acta 19, 201 (1963). ~a~ A. B. BURG and J. t-I. BICKERTON, J. Amer. Chem. Soc. 67, 2261 (1945); U. WANNA,Z;~.Xand R. PFEIFFENSCHNEIDER Z. anorg. Chem. 297, 151 (1958). ~t~ M. E. PEACH and T. C. WADOING'rON, J. Chem. Soc. 2680 (1962). ~ K. ISSLIEB and H. REINHOLD, Z. anorg. Chem. 314, 113 (1962).
Notes
The approximate coordinates of the uranium atoms could then be determined. The best fit was obtained with the following parameters in space group P21 :
x
y
z
0'98
0
0
0.33
0"97
0"65
0.67
0.99
0.34
0.17
0.23
0.79
0.67
0.26
0-87
The structure consists of pseudo-hexagonal layers at y = 0 and ½ with U-U-distances of 3.9 A. These layers are separated by sets of almost linear chains at y = ¼ and 3, parallel to the c-axis, at distances of 5"17 A from one another. A complete structure determination, based on X-ray and neutron diffraction data, is in progress and will be published in the near future.
Acknowledgement The author wishes to t h a n k Dr. E. H. P. CORDVUNKE for his stimulating interest and for providing the samples. P. C. DEBETS Reactor Centrum Nederland Petten, The Netherlands I. Inorg. Nucl. Chem.. 1964,Vol. 26, pp. 1470to 1471. PergamonPress Ltd. Printed in Northern Ireland Dissolution of refractory plutonium dioxide
(Received 19 February 1964; in revised form 27 March 1964) REFRACTORY plutonium dioxide dissolves only very slowly and incompletely in the more common mineral acids. BJORKLUNDTM found that the higher the temperature of preparation of the oxide, the more insoluble it was in potassium iodide-hydrochloric acid solution; correlation of this behaviour with X-ray diffraction and refractive index data led him to attribute the lower reactivity of the hightemperature oxide to the formation of a more perfect crystal lattice. Although potassium iodide-hydrochloric acid is partially effective for dissolving refractory oxide, the rate is low at room temperature and heating is not practical due to the evolution of iodine. Likewise, heating of commercial hydroiodic acid, which is stabilized with hypophosphorus acid, is not safe due to the release of phosphine, which can ignite spontaneously in air. Among the hydrohalic acids, hydrobromic acid ranks second to hydroiodic acid in acid strength and as a reducing agent; both of these properties should contribute to its performance in plutonium oxide dissolution. Furthermore, hydrobromic acid solutions may be boiled for long periods without excessive decomposition. Attention was therefore directed toward this acid as a possible solvent for plutonium dioxide. High-temperature plutonium dioxide was prepared by burning plutonium metal in air. For purposes of comparison, 10-g portions of this oxide were treated with 100 ml of boiling 16 M nitric, 12 M hydrochloric, and 9 M hydrobromic acids for 1 hr in covered beakers, after which each solution was diluted to 150 ml, filtered, and analysed for plutonium content. The results are given in Table l. TABLE I.--DISSOLUTION OF HIGH-TEMPERATUREPLUTONIUM DIOXIDE IN VARIOUS ACIDS Acid
Pu conc. g/l
PuO2 ( ~ ) Dissolved after 1 hr
HNO8 HC1 I-/Br
0.147 0.433 5.53
0.25 0.74 9.4
tl) C. W. BJORKLUND, USAEC Report LA-1869 (1954).
Notes
1471
The most commonly employed procedure for the dissolution of plutonium oxide involves extended reftuxing in concentrated nitric acid containing approximately 0.25 M fluoride ion. Frequently, however, insoluble oxide residues remain even after repeated treatment by this procedure. Because of the encouraging results obtained with hydrobromic acid, a programme was undertaken to dissolve a large quantity of these oxide residues in this acid. The procedure involved refluxing 500 g of the oxide in 1 1. of 9 M hydrobromic acid for 6-8 hr, followed by filtration. The solid residue was combined with 300 g of fresh oxide, refluxed in 9 M hydrobromic acid for 6-8 hr, and filtered as before. The filtrates were made basic with sodium hydroxide solution; the plutonium hydroxide precipitate was removed by filtration (the hydroxide filtrates being discarded), washed with water, and dissolved by adding it slowly to boiling nitric acid. Continued boiling for about 15 min efficiently expelled any residual bromine remaining in the solution. To minimize corrosion due to hydrobromic acid, the off-gases from both the reflux and boil-off operations were scrubbed with sodium hvdroxide solution. By continued repetition of the procedure, a quantity of oxide containing more than 3000 g of plutonium (as determined by sodium pyrosulfate fusion followed by radiometric assay) was dissolved, leaving a final residue containing less than 0.5 g of plutonium-a yield of greater than 99.98 percent. The plutonium content of the hydrobromic acid solutions after refluxing for 6 8 hr was 200 250 g L for those runs in which fresh oxide was added and for several runs after addition of fresh oxide ceased. (It was not considered desirable to attempt to obtain higher concentrations of plutonmm because of the possible crystallization of PuBr3 from the solution.) Finally, as the oxide became depleted, the concentration of the reflux solution decreased, generally by a factor of approximately two with each successive run. Treatment was discontinued when the plutonium concentration in the reflux solution became less than 1 g/l., although in most cases it would probably be more practical to stop before such a low concentration was reached. J. M. CLFVEt X~,D The Dow Chemical Comtoan)' Rocky Flats Diviffon Post Office Box 888 Gohlen, Colorado Since the elevation of this laboratory is 6000 ft, the boiling point of the nitric acid inixmre is lower (112 ° 114C, as compared to 120°-125°C at sea level), and thus the dissolution conditions are less rigorous than would exist if the operation were performed at sea level. This effect is considered to be minor, however.
J. Inorg. NucI. Chem., 1964. WoI.26, pp. 1471 to 1472. PergamonPress Ltd. Printed in Northern Ireland
Trimethylamine oxide complexes of non-transition metal halides (Received 13 February 1964)
RI=CENTLY complexes of transition metal compounds with trimethylalnine oxide (TMO) '~' and pyridine-N-oxide t~,2~ have been reported, but the only compounds of TMO with non-transition metal halides mentioned are TMO.BF~, ~3~ TMO.BCIs, TM 2TMO.SiFa, ~5~ 4TMO.SiCI~, ~:'~ and Ct' K. ISSLIEBand A. KREmICH, Z. anorff. Chem. 313, 338 (1961). !'zt j. V. QUAGt.IANO, J. FUJITA, G. FRANZ, D. J. PHILLIPS, J. A. WALMSLEYand S. Y. TYREI-:,J. Amer~ Chem. Soc. 83, 3770 (1961); R. L. CARHN, J. Amer. Chem. Soc. 83, 3773 (1961); S. KIDA, J. V. QUAGUANO, J. A. WALMSLEY and S. Y. TYREE, SDectrochbn. Acta 19, 189 (1963); Y. KAK~I;II, S. K~OA and J. V. QCrAGLIANO, Spectrochim. Acta 19, 201 (1963). ~a~ A. B. BURG and J. t-I. BICKERTON, J. Amer. Chem. Soc. 67, 2261 (1945); U. WANNA,Z;~.Xand R. PFEIFFENSCHNEIDER Z. anorg. Chem. 297, 151 (1958). ~t~ M. E. PEACH and T. C. WADOING'rON, J. Chem. Soc. 2680 (1962). ~ K. ISSLIEB and H. REINHOLD, Z. anorg. Chem. 314, 113 (1962).