yield principally the four-point species. Spproximately one half of the surface compounds could be removed by extended evacuation followed by hydrogenation a t even higher temperatures. The fact that an apprcciablc portion of the surface species could not be desorbed from the platinum and rhodium surfaces is indicative of a distribution of active sites of very widely differing energies.
man, H. M.,J . din. Chem. Soc. 71, 797 (1949). (4) Yang, A. C., Garland, C. W., J. Phys. Chem. 61, 1504 (1957).
LITERATURE CITED
( 1 ) Emmett, P. H., McKinley, J., “Ca-
talysis,” Vol. V, p. 431, Reinhold, Sew York, 1957. ( 2 ) hleites, L., Sicholson, D. E., “Handbook of Analytical Chemistry,” Chapter on Infrared Spectroscopy in the Sodium Chloride Region, NcGraw-Hill, Ken. York, in press. (3) Waddington, G., Knowlton, J. IT., Scott, I). R., Oliver, G. D., Todd, S. S., Hubbard, IT. X., Smith, J. C , Huff-
D a s E. NKCHOLS~S Research and Development Division Humble Oil &. Refining Co. Baytown, Tex.
RECEIYED for review April 32, 1960. .ICcepted June 15, 1960.
Radiochemical Evaluation of Solvent Extraction of Indium as the Bromide at High Concentrations SIB: ’l’lie production and analysis of high purity indium has niadt, it’ tiesirable to he able to separato trace, quantities of impurities from large quantities of indium. Many papers dealing with the solvent ext’raction of indiuin arc found in the literaturr, with tliosr hy Irving and Rossotti (I-4) heing perhaps the most complete and that’ by Sunderman and coworkcrs (6) tht. most rcwnt,. Of the, many articles seen hy the present author only that of Iiriox and Spiiiks ( 5 ) gave data on extractions on indium coiicentrations above 0.1.11, and tlicse data were not very complcte. The present paper reports the rewilt:: of extractions from solutions 0.1 to O.T.11 in indium.
solvent. anti the washing removed without mixing with the acid layer. The second extractiou. was then made with 5 nil. of fresh solvent. All extractions were made at room temperature. After the extraction a portion of the acid phase was removed for the radiation measurements. The exbraction srparations were evaluated by comparing the radioactivity of extracted and unextracted portions of the test 3olutions. The measuremt>nte of tlic gamma emit’ter? were made on 3 nil. of the solution in a glass via1 5 cm. high by 1.5 cm. in outside cliamctcr having :I 1-mm. wall thickness. ,111 of thv pwmma eniit’ters except lcad-210 \wre iiwssured with :I well-t~ye scintillation iounter. ?‘lie lead-210 solution \\-:IS measured n-itli :i sointillation spectronietrr with the ba*e
thc suppliers 11 ere diluted aiid ahquoted t o measure the required amount of the element using the data furnished by the suppliers for calculating the element concentrations The isotoppq uqcd are 3hon n in 1”lde I PROCEDURE
The extractiuiis were effected 111 1 6 1111. glass-stoppered centrifuge tube. by shaking vigorously by hand for 5 minutes 5 ml. of the hydrobromic acid solution containing the indium and the radioactive isotope with 5 ml. of the organic solvent. The phases were then beparateti in a centrifuge a t about 3300 r.p.m. for 5 minutes. When a second extraction wa5 to be done, the organic la? er from the firbt extraction n a s carefully removed with a pipet. the top of the tiilic \ ~ s q h e dwith 2 ml of fresh
REAGENTS A N D SOLUTIONS
A stock solution of indium was madc by , dissolving high purity nictallic indium in nitric acid, adding concentrated hydrobromic acid, and evaporating almost to dryness. Twice mort. the residue was dissolved in hydrobromic acid and evaporated almost to dryness. Finally, the nearly dry ma+ \\as put into solution and diluted to volume with 4.5N hydrobromic acid. For the experiments on the extractability of indium, portions of the indium stock solution were tagged with indium114 and diluted with water and hydrobromic. acid to the desired indium and acid concentrations. The solutions for the impurity separation experiments were prepared by adding to a portion of the indium stock solution a sufficient quantity of a radioactive element to obtain 10 y of inipurity element per gram of indium. The solutions were then diluted with water and hydrobromic acid to get thc desired indium and acid concentrations. A separate solution was made for each impurity element under study. Thv radioisotope solutions as received from 1366
ANALYTICAL CHEMISTRY
Table I.
Extraction Losses of Impurities with 2-Pentanone Extraction
Extracted _ _ _ _ _ _ c{ __ ______~~ 4.5N HBr 3.51%’ HBr l!!lenlc~Ilt
Isotope Usrd
Single extn
37.2 36.0 Y9 >99 74
Double extn. 79.c)
i. F. J. ('.) J . Chem. SOC.1955, 1027.
( 3 ) Zbid., p. 1938. (4) Zbid., p. 1946. ( 5 ) Knox, K. L., Spinks, J. \V. T., Cun. Chem. ProcessZnd. 30,KO.11, 85 (19463. ( 6 ) Sunderman, D. S., Ackermann, I. B., Meinke, W. W., A 4 ~ aCHEM. ~ . 31, 40
(1959).
EDWARI)
B.
OWENS
Lincoln Laboratory
?*lassachusetts Institute of Technology Lexington 73, Mass. Operated with support from the U. S Army. Snvy. a n d Air Force.
Colorimetric Determination of Palladium in Uranium-Fission E le me nt AI loys drh. In tht *tiidit)* cwiinc,c.ted nith the processing of fucxl- for thr Second I .\perirnental Breeder Rractor. it has I x m necessary t o determine lrsb than lc;C palladiuni ill uranium alloys contEiining ruthenium, molybdenum, zirconium. rhodium, and palladium. Although the spectrophotom(,tric detcsrmination of palladium with 2-nitrosoI-naphthol reported by Alvarez ( 1 ) :ind modified by C'hcng ( 2 ) hac the neces-
sary sensitivity, it could not be used Fsitli these alloys because of the large miount of uranium present. I n Cheng's procedure, the palladium iiaphtholate complex is formed a t a pI-1 of 1.5 to 3.5 in the presence of (ethy1enedinitrilo)tetraacetic acid (EDTA) to mask interfering elements, thc solution is made basic with ammonium hydroxide, and thr complc.; i i r\tractcd with toluene. Vntlt~rt h r v
conditione, uranium precipitatw as the diuranate and seriously interferes with the extraction. Alvarez used a somewhat similar procedure, but suggested that the extraction be made from a n acid solution. The excess reagent was then scrubbed out of the toluene with dilutr base. It appeared that the advantages of each method might be rombined to achirve a method which would be uscful VOL. 32, NO. 10, SEPTEMBER 1960
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