Radiochemical Determination of Fission Ruthenium in Aqueous Solutions A Nondistilla tion Technique R. R. RICKARD and
E. I.
WYATT
Analytical Chemistry Division, Oak Ridge National laboratory, Oak Ridge, Tenn.
b A radiochemical method for the determination of fission ruthenium in aqueous solutions i s described, which does not require distillation to effect radiochemical purity. The use of potassium periodate and sodium hypochlorite to retain ruthenium in an alkaline solution in the ruthenate and perruthenate state permits removal of many fission products from ruthenium b y coprecipitation with zirconium hydroxide. The ease of dissolution of finely divided ruthenium metal with alkaline potassium periodate or sodium hypochlorite adds flexibility. Approximately 1 hour is required for an analysis in duplicate, with precision and accuracy comparable to the distillation method.
REAGENTS
Ruthenium carrier, 10 to 15 nig. per ml. Prepare by dissolving 30 grams of RuC13.zH20in distilled water and diluting to 1 liter. Standardize in triplicate by pipetting 5-ml, aliquots of the stock solution into 123-m1. Erlenmeyer flasks and acidify 11-ith 10 ml. of 6 S hydrochloric acid. Heat in a hot water bath to 80" to 90" C. and add granulated magnesium slon 1y to reduce the ruthenium to the metal. After coagulation of the ruthenium metal, dissolve the excess magnesium b y dropwise additions of concentrated hydrochloric acid. Filter the ruthenium metal v hile hot through a tared medium-fine glass frit, wash the metal n i t h hot distilled water, and dry with ethyl alcohol and diethyl ether \vashes. Desiccate the frit in a vacuum desiccator for 10 to 15 minutes, then remove the frit and weigh. The carrier yield can be expected to b r between 10 and 15 mg. per ml. Zirconium carrier, approximately 10 mg. per ml. Prepare by dissolving 35 grams of ZrOC12 8H20 in 1 liter of distilled water.
T
most widely used methods for the radiochemical determination of ruthenium require distillation of ruthenium as the tetroxide from a strong oxidizing medium to remove it from the other fission products. Coryell and Sugarman ( 2 ) describe a n excellent distillation technique employing perchloric acid and sodium bismuthate as the oxidants. Others (3, 6, 7 ) have described coprecipitation techniques applicable to the concentration of fission ruthenium from reactor waste solutions. The method described here does not require distillation and can be applied to most of the samples for which a distillation is possible. Citrate, phosphate. oxalate, and none of the mineral acids interfere; tartrates interfere by forming a complex with ruthenium, as do the glucosides. HE
Table I.
PROCEDURE
Pipet an aliquot of a sample into a 50ml. glass centrifuge tube, add the ruthenium carrier and 2 ml. of concentrated hydrochloric acid, and heat to boiling. Cool, and cautiously add 1 6 X sodium hydroxide dropwise TT ith frequent stirring until hydrolysis of the ruthenium is evident. then 1 ml. in excess. Add 20 to 30 ml. of a saturated potassium periodate solution in distilled water and, while stirring, slowly heat to boiling over a flame. Add 1 ml. of 5yosodium hypochlorite and digest the solution a t room temperature for 10 minutes. Sodium hypochlorite ensures the oxidation of
Radiochemical Determination of Ruthenium in Mixed Fission Products
Gross Gamma, Sample History Thorium dissolver Uranium dissolver Thorium process sample Granium development sample
50
e
ANALYTICAL CHEMISTRY
C.P.i\l./RIl. 7 x 107 6 X 1Ol1
x x 5 x 2 x 5
100
3
107 107 107
Ru Gamma, C.P.M,/Ml Dist. method Sondist. method 3 . 4 x 106 2 1 x 109 2 6 X lo8 1 . 4 0 X loT 7 . 3 x 106 6 . 6 X lo3
3 3 x 106 2 . 1 x 100 2 6 X lo8 1 . 4 3 x 107 7 . 3 x 105 6 . 4 x 103
any nitratonitrosyl ruthenium. The color \vi11 change from an orange to a greenish bron n. rlbsorption spectra indicate the presence of ruthenate ( 5 ) and perruthenate (1, 8) ions. Add 1 ml. of zirconium carrier, stir the solution thoroughly, and centrifuge. Discard the precipitate which contains most of the fission products. Decant the clear supernate into clean centrifuge tubes and add 1 ml. of zirconium carrier. Stir the solution xell and centrifuge. Decant the supernate into clean centrifuge tubes, add 1 ml. of ethyl alcohol, stir, and digest in a hot water bath to coagulate the hydrated ruthenium oxides. Cool, centrifuge, and discard the supernate. T a s h the precipitate with 2-11 sodium hydroxide, stir, centrifuge, and discard the wash solution. Dissolve the precipitate with 2 ml. of 6 J I hydrochloric acid with occaqional heating ovcr a flame. Add an equal volume of distilled water and add magnesium metal turnings slonly to reduce the ruthenium to the metal. After coagulation of the ruthenium metal, dissolve the excess magnesium with concentrated hydrochloric acid. Centrifuge and discard the supernate. K a s h the ruthenium metal with hot distilled water, centrifuge, and discard the wash solution. Dissolve the ruthenium metal n ith several drops of 16M sodium hydroxide and 2 ml. of 570 sodium hypochlorite (4). Sufficient alkali is needed to prevent volatilization of ruthenium tetroxide. Heat gently over a flame and stir to obtain complete dissolution. Add 5 to 10 ml. of distilled water and 1 ml. of zirconium carrier. Stir the solution and centrifuge. Transfer the supernatant liquid into a clean crntrifuge tube and add 1 ml. of ethyl alcohol. Digest in a hot mater bath to reduce and coagulate the ruthenium hydroxide. Centrifuge and discard the solution. Wash the precipitate with 2 X sodium hydroxide. Centrifuge and discard the mash solution. Dissolve the precipitate nith 2 ml. of 6111 hydrochloric acid. Heat oyer a flame to dissolve the precipitate completely. Reduce the ruthenium to the metal by careful addition of magnesium metal. Swirl to coagulate the metal, dissolve the excess magnesium metal 1%-ith concentrated hydrochloric acid, and centrifuge. Discard the liquid and xvash the metal precipitate with hot distilled water. Discard the Ivater wash solution. Col-
lect the metal on a tared filter paper (2cni. diameter), and \Tash nith hot water, 95% ethyl alcohol, and dicthyl ether. TVc4gh. mount, and count the isolated ruthcnium. RESULTS A N D DISCUSSION
Table I summarizes thc, rrsults of rutheniuni analyses of aqueous solutions of mixed fission products hy both thc, distillation method of Coryell and Sugarnian ( d ) and the mrthod described. The pi,ccision of the method is coniparable to that obtainc4 by the distillation method, + 3 to A%,. Tlic data in Table I illustrate the accuracy obtainable n-hen t,lie method described is carefully followed. The nietliocl is flexible, in that the rutlieniuni metal can easi]:. lie dissolved 11-ith potassium
periodate or sodium hypochlorite and a series of zirconium hydroxide scavenges can be made. Decontamination factors of the order of lo4 have been obtained froni the other major fission products and protactinium with the carrier yield about i&. The method describcd is suggested as another means of performing radiocheniical ruthenium analyses. even though the decontamination obtained and t,he analytical time required are not inigrovenients over the distillation t"hniquc. The method (n.ith modifications) has been routinel:. used to determine low concentrations of ruthenium activity in large water volunies. The oxidation of rutheniuni with potassiuni periodate in an alkaline niediuni and fixation n-ith sodium hypochlorite (8) are useful in decontaniination of glassware, and application as a lracliing agent for
fission ruthenium in sonie soils is being investigated. LITERATURE CITED
(1; Connick, R. E., Hurley, C. R., J . A m , Chem. SOC.74, 5012 (1952). ( 2 ) Coryell, C. L),>S u p m a n , S., ',Iiadiochemical Studies. i he Fission l'rodiicts," paper 260. 1). 1549, 1 I d ; r a w Hill, S e w York, 1951. ( 3 ) Gresky, A. T., L-, S. htoniic 1;iiergy Comm., Re;it. ORNL-614 (1950). ( 4 ) Hopkini, B. S., "Chapters i n the Chemistry of thc Less Yaniiliar Elements," 1-01.11, 11. 2;3! Stipe3 Pulilishing Co., Champaign, Ill.. 1939, ( 5 ) Marshall, E. D , , Itickard. It. R . , . % S A L . CHEM. 22, (1'350). ( 6 ) \lead, F. C., Jr., C . ti. .Itoiiiic Eriergy Comm., Rept. AECD-49 (1949). (T) [bid., MLM-30 (19491. ( 8 ) Stoner, G . -1.) .Is.LI, CHEII. 27, 1186 (1955).
RECEIVEDfor revien- J d y .iccepted October 9, 1958.
T,
1038.
Determination of -Hydrogen in Alkali Metals by Isotope Dilution Method BEN D.
HOLT
Argonne National laboratory, lemont, 111
b The rapid exct,ange of hydrogen and deuterium in sodium or NaK affords a convenient method for hydrogen determination in these metals. Spikes equivalent to 5 to 250 p.p.m. of hydrogen have been recovered on 2gram samples with a standard deviation, from the quantity added, equivalent to * 2 p.p.m. An 8-inch borosilicate sampling tube serves as the reaction vessel and as the gas bulb for mass spectrometric analysis. With many such tubes on hand, samples can b e taken a t sites of industrial operations and transported to the laboratory for analysis. In the analysis of NaK it i s nec?ssary to apply a correction factor to compcnsatz for the effect of diffsrent rates of formation of the l-,ydrides and deutyrides in the cooler zon+s of the tub3 during equilibration. For sodium this e f f x t i s negligible and no correction i s necessary. The time required for analysis after the sample is taken is about 4 hour.
I
in liquid-metal-cooled reactors during the past decade has necessitated a good method for the determination of hydrogen in alkali metals and alloys. A few years ago Pepkowitz and Proud (6) reported a XTCREST
unique method by v, liich t,lie metal was heated to 700" (I. in a sealcd iron can and the resulting hj-drogen pressure surrounding the can in a Twuuiii system \vas taken as a measure of thc hydrogen content of the sample. Successful use of this niet,hod deniands conipl& liberat'ion of all the hj-drogrn from the sample into thc gaseous phase. Tests niadc a t this laboratorj- indicattd that liberation of hydrogen \I as not cwnplet,e. but n-as controlled by an apparrnt equilibrium bet w e n the liberated hjdrogc,n outside the can and thc heutcd sample inside the can. Willianis' study (8) of the sodium-hydrogen-ox>-gen sj-stem appears to lend support to this idea. The isotope dilution t,cchniquc ( I , 3: 4, 7 ) is not hindcred bj. such an equilibrium but is dependent upon it. Simpson and Kauh (6' p r o p o s d an isotopc dilution method in n.liich the metal was converted to osidcs by purified oxygen and equilibrat'cd ith dtwtoriuni oxide of Iinon.11 purity with rcspwt to hydrogen. By mass spectronietric analysis of the dcuterium oxidv distilled from the equilibrium solution, an rstimate could be madc of the hydrogrn contributed by the sample. Poor prccision was attributed to the very great difference in magnitude of the quantities of the two isotopes and to the accumulative contamination errms involved in the various
stcps of handling the deuteriuni osidc and the sample. A simplified iscitopc dilution nicthod for hydrogen in sodium and S a K is presented, which is similar to a teclinique used by Zaidei and Petrol. (9)for hydrogen in zinc. iron, and Xichrome. APPARATUS
Figure 1 s1ion.s the pi1)cttc.r used to delivcr a mcasi:rcd quantity of 99.5% pure deuteriuni into thc r;ampling tube. T o siniplif!~ calculations the same yiantity was taken for ever>- s a n i i ~ l (and ~ Iilank. The volunir of thc pipet' hulb was 21.39 cc.; the tcnipcrature was held constant by room air-conditioning; and the pressure W R S adjustc~don the open-well manonictcr. The 8-inch. borodicate sampling tube served as the equilibration vessel and as the gas 11~111~for niass spectrometric analysis. Its il(4ccator-type stopcock was fabricated from a 24, 25 standard taper joint. To Vac in Figure 1 refers to a vacuum line leading through a li !,uid nitrogen trap t,o a Duo-Seal mechanical pump. X tilting 11cLeod gage on this line was used to cheek the final pressurc in the sampling tubcls after evacuation. A 4-inch Hevi-Duty electric tube furnace was used to heat the tubes for ecuilibration of the isotopes. Set vertically on a firebrick base, and lined with brass pipe 1 inch in inside diameter, the furnace held the tube in an VOL. 31, NO. 1, JANUARY 1959
51
