V O L U M E 2 5 , NO. 10, O C T O B E R 1 9 5 3 3. Extract three times for 5 minutes with 5 nil. of diisopropyl ketone (remove ketone with saran pipet). 4. Combine and wash organic layers in polyethylene three times with 5 ml. of a 3olution 6 -1.I in sulfuric acid and 0.4 M in hydrofluoric acid. 5. Back-extract tantalum three times for 1 minute with 5nil. portions of 6 -11 hydrochloric acid containing boric acid and combine in glass. 6. Wash aqueous phase once for 1 minute with 10 ml. of diiwpropyl ketone; discard organic phase. i . Add 1 drop of phenolphthalein t o aqueous phase, make basic. with ammonium hydroxide, add 1 drop of 2% aerosol, digest hot, and centrifuge. 8. Wash with ,slightly basic ammonium nitrate solution. 9. Waah twice with fuming nitric acid, digest, and rentrifuge. 10. Transfer to Lusteroid cone, and dissolve precipitate in a solution 6 31 i n sulfuric acid and 0.6 M in hydrofluoric acid. 1I . Tranqfer to polyethylene cone and repeat steps 3 through 9. 12. Transfer tantalum precipitate t o platinum crucible, ignite, and weigh a? TazOs.
A fission product separation procedure has been devised for niobium t o give decontamination factors of 1OBfor all other fission products. 1. Dissolve uranium target in concentrated hydrochloric< acid to which niobium carrier has been added in oxalate form (Lusteroid tube). 2 . ildd a drop of concentrated hydrofluoric acid, and clear solution n-ith a few drops of concentrated nitric acid and digestion. 3. Transfer t o polyethylene cone, adjust to 6 JI in hydrochloric acid, and extract three times with half volumes of diisopropyl ketone. Discard organic layer. 4. Add sufficient concentrated hydrochloric acid and hydrofluoric acid t o make the solution 6 .If in hvdrochloric acid and 9 j I i n hydrofluoric acid. 5 . Extract three times with half volumes of diisopropyl ketone, and combine ketone layers. 6 . Wash combined organic layers three times with a solution 6 .lI in sulfuric acid and 9 .II in hydrofluoric acid.
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T. Extract niobium from ketone three times with half volumes of water. Collect water layers in a tube containing iaturated boric acid solution. 8. lldd phenolphthalein, make just basic with ammonium hydroxide. and digest. 9. Wash niobium precipitate twice with slightly basic ammonium nitrate qolution, then twice with concentrated nitric acid. 10. Trander precipitate to polyethylene cone and dissolve in a wlution 6 Jf in d f u r i c acid and 9 'If in hydrofluoric acid. 11. Repeat steps 5 through 9. 12. Transfer precipitate to platinum crucible, ignite, and n-eigh as Sh20s. CONC LUSION s
Tantalum and niobium can be separated by preferential extraction of the tantalum into diisopropyl ketone from mineral acid-hydrofluoric acid aqueous systems. Siobium may also be separated from nearly all other elements by extraction from solutions suhstantiallg higher in acidity and hydrofluoric acid concentrat ion. ACKNOWLEDGBlENT
The authors wish t o thank R. S. Gilbert, IV. H. Hutchin, and Margaret Servik for their assistance in the experimental work. This n ork was done under the auspices of the U . S. Atomic Energy Commission. LITERATURE CITED
(1) Miher, G . W. P , , and Wood. -4.J., Ministry of Supply, Great Britain, Atoniic Energy Research Establishment, rnczassified Rept. C I R 895 (1952). (2) Servik, W. E., private communication. (3) Wood, G. A., Ministry of Supply, Great Britain, Chemical Research Laboratory, Cnclassified Rept. CRL/AE-62 (1960); obtainable from Technical Information Division, U. S. dtomic
Energy Commission, ORE, Oak Ridge, Tenn. RECEIVED f o r review .January 13, 1933. Accepted July 2 2 , 1953. Report 2009.
UCRL
Precipitation of Iodates from Homogeneous Solution Separation of Thorium Iodate C l W L E Y R . STIYEl
. ~ N DLOUIS
GORDOY
D e p a r t m e n t of C h e m i s t r y , Syracuse I.nicersity, Syracuse 10, 3..E'.
i method was desired for the synthesis of iodate ion in homogeneous solution to be used for the precipitation of dense insoluble iodates. Thoriunl iodate mal he precipitated from homogeneous solution in a dense and granular form with iodate produced by the reduction of periodate with ethjlene gljcol, which is slowl? produced by the h>drol>sisof 6h>drox>eth? 1 acetate. The precipitate thus obtained is easil! washed and filtered. With a single precipitation less contamination b> foreign ions is
T
HE use of the iodate ion as a precipitant has been limited, although methods utilizing iodate in nitric acid solution have been described for thorium ( 9 ) , cerium(1V) (Z), and titanium ( I ). As the iodate ion can form insoluble compounds with several cations, other methods could be developed-zirconium iodate ( 1 6 )has been characterized as almost insoluble in nitric acid solution and precipitation of iron(II1) as the iodate (3)has been suggested as a separation from aluminum.
' Present address. E. I
d u Pont de Piemours & Co., Inc., Wilrnington, Del
encountered than in the conventional heterogeneous method. Upon a double precipitation, this method effects quantitative separation of thorium from large amounts of rare earths and phosphate. Because of increased efficiency of separation, an improved procedure is possible for the determination of thorium in monazite sand. As there are other insoluble iodates, this method also presents possibilities for improving the quantitative separation of other cations which normally form gelatinous iodates.
The eytremely gelatinous character and the concomitant coprecipitation b?- such iodates have perhaps been deterrent factors in the development of iodates as precipitation forms. The physical characteristics of such precipitates can be markedly improved b y precipitation from homogeneous solution ( 4 , 1 7 ) . This has already been accomplished with cerium (19 ) , thorium ( 5 ) ,and zirconium (8). Cerium(II1) does not form an insoluble iodate, but it can be slowly oxidized t o cerium(1V) in the presence of iodate to form a
LYTICAL CHEMISTRY
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I
dense precipitate. An excellent method (f9)has been recently developed in which cerium is thus separated from the other rare e:
ic e s
