with Dowex 1 and decreases with Dowex 2. Thorium in nitric acid and uranium(V1) in sulfuric acid show resin adsorptions with Dowex 2 similar to Dowex 1. Uranium(V1) in nitric acid shows a different adsorption function with Dowex 2 than with Dowex 1, although the magnitude of the maximum adsorption is similar. ACKNOWLEDGMENT
The authors thank S. W. Alayer and E. C. Freiling for helpful discussions and suggestions. LITERATURE CITED
(1) Bunney, L. R., Freiling,
E. C., McIsaac, L. D., Scadden, E. M., Xucleonics 15, No. 2, 81 (1957). ( 2 ) Burgus, W.H., Engelkemeir, D. W., “Radiochemical Studies. The Fission
Products,” K.N.E.S., Vol. IV, p. 9, Paer 291, ed. by C. D. Coryell and N. gugarman, McGraw-Hill, New York, 1951. (3) Campbell, E. C., Nelson, F., Phys. Revs. 91,499A (1953). (4) Diamond, R. M., Street, K., Jr., Seaborg, G. T., J . Am. Chem. SOC.76, 1461 (1954). (5) Glendenin, L. E., “Radiochemical
Studies: The Fission Products,’J N.N.E.S., Vol. IV, p. 9, Paper 236, ed. by C. D. Coryell and N. Sugarman, McGraw-Hill, Yen- York, 1951. (6) Ibid., Paper 260. ( 7 ) Hacke, O., 2. anal. Chem. 119, 321 (1940).
(8) Harned, H. S., Owen, B. B., “Physical Chemistry of Electrolytic Solutions, Reinhold, NeIY York, 1950. (9) Kraus, K. A., Nelson, F., “Anion Exchange Studies of the Fission Products,” Paper 957, Session 52, International Conferences on the Peaceful Uses of Atomic Energy, 1955. (10) Kraus, K. A., Kelson, F., Clough, F. B., Carlston, R. C., J . Am. Chem. SOC.77,1391 (1955). ( 1 1 ) Kunin, R., McGarvey, F. X., ANAL. CHEM.26, 104 (1954).
(12) Kunin, R., McGarvey, F. X., Ind. Eng. Chem. 47,565 (1955). (13) Lindner, M., “Radiochemical Procedures in. Use at the University of
California Radiation Laboratory, (Livermore),” UCFU-4377 (1954). (14) Meinke, W. W., “Procedures Used in Bombardment Work at Berkeley,” UCRL-432 (1949). (15) Samuelson, O., “Ion Exchangers in
Analytical Chemistry,” Wiley, New
York, 1953. (16) Scadden, E. M., Ballou, N. E., AXAL.CHEM.25, 1602 (1953). (17) Stevenson. P. C.. Hicks. H. C..’ ‘ Ann. Rev. N&leur Sd 3, 221 11953). (18) Thomason, P. F., Perry, M. A., Byerlv, W. M., ANAL.CHEW21, 1239 (i949j: (19) W~sh,L., private communication. (20) Wish, L., Freiling, E. C., Bunney, L. R., J . Am. Chem. SOC.76, 3444 (1954).
RECEIVEDfor review May 23, 1958. Accepted December 15, 1958. Division of Analytical Chemistry, Symposium on Radiochemical Analysis, Fission Product Analysis, 133rd Meeting, ACS, San Francisco, Calif., April 1958.
Qu a ntita tive RadiochemicaI An a lysis by lon Excha nge Anion Exchange Behavior in Mixed Acid Solutions and Development of a Sequential Separation Scheme LEON WISH
U. S. Naval Radiological
Defense laboratory, Son Francisco 24, Calif.
b A method for rapid separation and determination of neptunium, plutonium, uranium, zirconium, niobium, and molybdenum isotopes in mixed fission products is evolved from Dowex 2 anion exchange equilibrium data on these elements in hydrochloric, hydrochlorichydrofluoric, and nitric acids. The fission products sample in concentrated hydrochloric acid is added directly to the resin column, and no tracers, carriers, or prior separations are required. The activities are eluted sequentially and determined directly in a y-ray scintillation well counter or a multichannel y-ray spectrometer. The yields are quantitative and the purity is equivalent to that obtained from the standard radiochemical procedure for molybdenum, neptunium, and Plutonium. The zirconium and niobium fractions may contain y-ray impurities which are easily resolved by y-ray spectrometry. The uranium is contaminated with the tellurium-1 32iodine-1 3 2 pair and usually requires further purification.
T
quantitative determination of radionuclides in products of neuHE
326
ANALYTICAL CHEMISTRY
tron irradiations of uranium and other heavy elements usually requires yield determinations, because decontamination procedures result in significant losses. A measured quantity of a different isotope of the element to be determined is added and if there is suitable isotopic exchange, the yield of the unknown will be the same as for the known. Alpha-ray tracers, neptunium237, uranium-233, and plutonium-236 are used to determine the radionuclides of these elements-e.g., neptunium239, uranium-237, and plu tonium-239. Milligram amounts of the stable elements are required for zirconium-95, zirconium-97, niobium-95, and molybdenum-99. These analyses are usually rather lengthy, especially those for the heavy elements uranium, neptunium, and plutonium, which require electrodeposited samples for suitable alpha counting. I n the past few years, ion exchange separations have materially simplified some radiochemical procedures and increased the over-all yields for many isotopes. Also, y-ray spectrometry has become increasingly useful for qualitative and quantitative analysis and for detection of contaminants. Complete
y-ray spectra can now be obtained in a short time with a 256-channel analyzer. The efficiency of y-ray detection has been sharply increased with scintillation sodium iodide-thallium crystal counters, and gamma counting of liquid samples is now precise and accurate. Connally (2) gives a good review of the instrumental methods of y-ray spectrometry. It would be extremely advantageous to add any fission product mixture directly to a n ion exchange column and elute the desired radionuclides quantitatively and sequentially with sufficient purity, thus eliminating the need for tracers and carriers. The eluates containing these gamma-emitting isotopes could then be transferred directly to a scintillation well counter and spectrometer for activity and purity measurements, so that decay measurements i ~ o udl be eliminated. ,4 sequential separation method for uranium, neptunium, and plutonium (16) utilized hydrochloric acid and nitric acid as eluents. However, the eluted uranium was grossly contaminated with zirconium and required further processing. It was necessary to separate ‘the molybdenum activity by precipitation prior to ion exchange, as it
usually appeared in all fractions. The yields varied from 50 to 90% with losses occurring in purification, electrodeposition, and the ion exchange procedure. I n 1949 Kraus and Moore (8) reported the successful use of hydrochloric-hydrofluoric mixtures in the separation of zirconium from hafnium and niobium from tantalum using Dowex 1 anion resin, and this was later confirmed by Huffman and Lilly (6, 6) and Kraus and Moore (IO). The latter authors have extended these separations to protactinium, niobium, and tantalum ( I I ) , to protactinium and iron ( I d ) , to zirconium and niobium (9), and to molybdenum, tungsten, and uranium ( I S ) . Hague, Brown, and Bright (3)have reported the separation of titanium, tungsten, molybdenum, and niobium in hydrochloric-hydrofluoric medium. In practically all, the hydrochloric-hydrofluoric elutions were much sharper with little or no tailing and offered an excellent chance for quantitative recoveries.
coefficients above 100, whereas neptunium, plutonium, and uranium have less adsorption with coefficients of 15, 37, and 8.3, respectively. As the hydrochloric acid concentration increases, the adsorption decreases rapidly to a minimum for all the elements. However, the extent of the decrease and the rise thereafter varies considerably, as shown in Table I, which gives the coefficients for 0.1N and 12N hydrochloric acjd and for the nijnimum adsorption; acid strength is given in parentheses. Kraus, Selson, and Moore ( I S ) with Dowex 1 reported a similar adsorption for molybdenuni(V1) and uranium(V1) using lAr hydrofluoric acid with varying hydrochloric
EQUILIBRIUM EXPERIMENTS
The adsorbabilities of the various isotopes on Dowex 2, X8, 200 to 400 mesh, were determined in hydrochlorichydrofluoric mixtures by shaking a known volume of solution containing the radioactive tracer with a known weight of resin in 1-ounce polyethylene bottles for a t least 20 hours until equilibrium was reached. The distribution coefficient, K d , was then obtained from the reaction: activity per gram of resin K d = activity per milliliter of qolution Weights and volumes were chosen to give an approximately equal distribution of the activity between the two phases when possible. All experiments were at room temperature and there was no attempt to control either humidity or temperature. The radionuclides used in the equilibrium determinations and subsequent column runs were zirconium-95, niobium-95, molybdenum99, uranium-237, neptunium-239, and plutonium-239. The isotopes were purified by standard radiochemical and ion exchange techniques and checked by decay and y-ray spectrum measurements. All activities except plutonium-239 were measured in a yray scintillation well counter using a proportional scaling unit.
Figure 1 . Equilibrium distribution coefficients in hydrochloric-hydrofluoric acid solutions
RESULTS
Figure 1 is a plot of the distribution coefficients us. the normality of hydrochloric acid solutions containing 0.3'Y hydrofluoric acid. The oxidation states are neptunium(IV), uranium(V1) , plutonium(IV), zirconium(IV), molybdenum(T'I), and niobium(V). Zirconium, niobium, and molybdenum adsorb strongIy in 0.LY hydrochloric acid with
0
c
ci
04
31
Y
C l
"6
- 7
HF
Figure 2. Equilibrium distribution coefficients in hydrofluoric acid solutions
Table I. Equilibrium Adsorption Coefficients ( K d ) in Hydrochloric Acid Solution, 0.3N in Hydrofluoric Acid Ele- 0.1N 125 ment
U Np Pu
HC1 8.3 15 37
530 275 340 225 Zr
Nb
Minimum 0.6(1ArHC1) O.OS(5NHCI) O.Ol(ca. 4,V
HCll
0 . 2 7 '(SA7 HCI) ( 6 X HC1)
4.2
18
(2iVHC1)
HCl
830 30
li25 0.40 15.5 450
acid concentration. The adsorption coefficient of molybdenum is large in 0.1N hydrochloric acid, decreases n-ith increasing acid strength to a minimum, 18, near 2N, and rises to about 100 in 12N acid. They found the same effect for uranium, except that the adsorption below 3 X acid is less than that of molybdenum and considerably greater above 31v. Kraus and hloore (9) found zirconium(1V) to be weakly adsorbed in the mixed acid solutions above I N hydrochloric acid and very strongly adsorbed in lon-tr chloride concentration. This is in agreement n-ith the data in Figure 1. I n Figure 2, the hydrofluoric acid concentration is varied from 0 t o O.6N while hydrochloric acid is constant12N for zirconium, 8 N for neptunium, 10N for niobium, and 6,V for molybdenum. From 0 to 0.06N hydrofluoric acid the Kd's for zirconium and neptunium are reduced from 35 to 0.8 and from 700 to 1.5, respectively. The O.06N hydrofluoric acid has less effect on the adsorption of niobium, Kd being reduced from 1000 to 93, and a smaller effect on molybdenum, 340 to 255. This indicates the initial formation of a strong complex ion of the elements with fluoride ion. There is also a significant change when the hydrofluoric acid is increased from O.06N to 0.W. For niobium the decrease in the coefficient is about threefold, but is less for rnolybdcnum, neptunium, and zirconium. Yiobium and neptunium show a niininiuni adsorption in 0.35 hydrofluoric acid but in 0.6N hydrofluoric acid the increase in K d is relatively small, 8.5 to 19 for niobium, and 0.34 t o 0.58 for neptunium. Kraus and Moore (9) found a similar effect for zirconium and niobium-the niobium adsorption is more dependent on fluoride concentration than zirconium. For comparison the equilibrium adsorption in hydrochloric acid solutions is given in Figure 3, part of Ivhich appeared in an earlier report (16). The molybdenum, zirconium, and niobium curves were furnished by Bunney, Ballou, Pascual, and Foti ( I ) . Kraus, Xelson, and Moore (IS) studied the adsorption of molybdenum from hydroVOL. 31, NO. 3, MARCH 1959
* 327
chloric acid solution using Dowex 1 and their coefficients decrease rapidly as the acid concentration falls below 2 N . This contrasts with Figure 3 which shows a sharp increase below 2N acid with a coefficient of 700 for 0.1N Xeloche and Preuss (14) using IRA-400 resin, and more recently Huffman, Oswalt, and Williams (7) have published molybdenum curves in hydrochloric acid which essentially agree with that obtained from Dowex 2. Dowex 2 column experiments in the past have indicated that molybdenum(V1) is not eluted with low normality hydrochloric acid. Bunney et al. ( 1 ) have found that molybdenum(V1) adsorbs strongly in 0.1N nitric acid, but the adsorption decreases rapidly with increasing acid concentration so that in 12N nitric acid K d is approximately 0.4 Huffman, Oswalt, and Williams (7) have reported similar equilibrium data for technecium.
ELUENT, ML.
Figure 4. Elution of zirconium from Dowex 2 anion exchange column
EXPERIMENTAL COLUMN STUDIES
The tracer element in concentrated hydrochloric acid was added to the Dowex 2 resin column, 0.2 by 15 cm. (15). However, because the glass woo1 plug a t the bottom of the resin would be attacked by the hydrofluoric acid, one composed of Lucite shavings was substituted The hydrofluoric acid concentrations were low enough to permit the use of glass columns. The flow rate was approximately 1 ml. per 3 to 5 minutes, and the eluate was collected in 20-ml. Lusteroid tubes, inserted in the well counter for activity determinations. The fractions were 1 to 2 ml., as calibration of the counter showed no significant change in the counting efficiency from 0 to 2 mi. total volume. All loading solutions and washes were measured in this manner, and it was also possible to insert the column itself in the counter to check for any residual activity after a run. When mixtures of isotopes were used, the fractions were checked for purity in a 256-channel -pray analyzer. As a further teat, the decay of the shorter-lived activities was followed for several half lives. QUANTlTATlVlTY OF ELUTIONS
The recoveries are quantitative, with standard deviations of 0.2% for 37 determinations. All the isotopes are eluted in 10 ml. or less. I n Figure 4 the zirconium elution curves with very low hydrofluoric acid concentration show three distinct sections: a very rapid initial removal, a region of constant elution, and a further rapid removal. I n Figure 4, A , the zirconiuni is eluted with 12N hydrochloric acid containing increasing amounts of fluoride from 0.08 t o 0.W. The intermediate "plateau" decreases in height and with 0.4N hydrofluoric acid practically disappears. Figure 4, B
328 *
ANALYTICAL CHEMISTRY
,
m: -
Figure 3. Equilibrium distribution coefficients in hydrochloric acid solution
and C, shows that with 11 and ION hydrochloric acid the plateau is small for the former and nonexistent for the latter in 0.16N hydrofluoric acid. The zirconium elutions might be explained by the presence of two ionic species. The predominant species is easily eluted and its presence is favored by high fluoride concentration. It therefore probably contains more fluorides per ion than the second, less abundant species, which is decreased and eventually eliminated by either increasing fluoride ion concentration or decreasing chloride ion concentration. I t would then seem to be either a chloride or mixed chloride-fluoride complex. OPTIMUM ELUTING CONDITIONS
The equilihrium data for hydrochloric-hydrofluoric acid mixtures (Figure 1) indicate that a successful sequential procedure would be especially dependent on satisfactory separation of niobium from neptunium and of uranium from molybdenum. Because the latter two elements would be the last eluted, i t is essential to maintam their adsorption on the resin during most of the procedure. This requires that their oxidation states be molybdenum(VI) and uranium(V1) a t all times. Bromine water added to all the eluents helps to maintain these higher oxidation states, as uranium map be reduced in the resin (16). The hydrochloric acid concentration must also be decreased to 1N or less without establishing an intermediate concentration of 4 N in which the molybdenum adsorp-
tion is minimal. This is accomplished by drying the resin column with air, followed by washing with a few column volumes of alcohol or ether. Separation of Neptunium from Niobium. Several column runs were carried out to determine t h e hydrochloric and hydrofluoric acid concentrations which would be practical for t h e quantitative separation and recovery of neptunium and niobium. These indicated t h a t elution of neptunium is rapid below 7 N hydrochloric acid with as low as 0.004N hydrofluoric acid. With 0.25N hydrofluoirc acid or above the neptunium eluted slowly in 1ON hydrochloric acid. I n other experiments a significant portion of the neptunium activity was eluted even in 12W hydrochloric acid with more concentrated hydrofluoric acid, but a 13.7.V saturated hydrochloric acid solution with 2.3.V hydrofluoric acid eluted no neptunium. I n 6.0N hydrochloric-0.004.V hydrofluoric acid some of the niobium is eluted, but by increasing the hydrochloric acid concentration to 6.5N the niobium is retained on the column. The niobium activity is readily eluted with 6A' hydrochloric acid containing a t least 0.09N hydrofluoric acid, and increasing the hydrofluoric acid to 0.3N had little effect on the nature of the elutions. However, elution with lower fluoride concentration is desirable, as it would increase the adsorption of elements remaining on the column-e.g., uranium and molybdenum. A typical elution of a mixture of neptunium-239 and niobium-95 is shown in Figure 5 . Neptunium was separated with 10 ml. of a 6.5N hydrochloric0.OOzN hydrofluoric acid mixture and niobium with 5 ml. of 6.ON hydro-
1-
65 0004-
--j
00 6 3 --
~
-
NP*'~
! I
~
3c
I
I,:
ELUENT
Figure 6. Elution procedure Dowex 2 anion resin
VOLUME l M L l
Figure 5. Separation of neptunium2 3 9 from niobium-95 with hydrochloric-hydrofluoric acid solutions
chloric-0.3N hydrofluoric acid, with yields of 100.7 and 100.4%, respectively. Separation of Uranium from Molybdenum. Uranium(V1) has little adsorption on Dowex 2 in 1 N hydrochloric acid solution, with or without hydrofluoric acid, whereas molybdenum(V1) has its lowest distribution coefficient (Kd = 10) in 2 N hydrochloric acid or 2 N hydrochloric0.3N hydrofluoric acid solutions. Attempts t o separate t h e two elements by elution with 1.0 and 2.ON hydrochloric-hydrofluoric acid mixtures have been unsuccessful; appreciable amounts of molybdenum contaminated the uranium fraction. However, Table II.
No. 1
2
3
4
5
6
7
y
as the hydrochloric acid concentration is decreased below 1W the adsorption of molybdenum increases much faster than that of uranium (Figure l ) , so that in 0.1A4' hydrochloric-0.06S hydrofluoric acid there is no observable cross contamination. The molybdenum-99-technecium-99 pair is then eluted with 12N nitric acid. PURITY OF FRACTIONS
Figure 6 summarizes the elution procedure which was tested on seven radionuclide mixtures obtained from neutron bombardment of uranium isotopes. Zirconium. I n most cases t h e y-ray spectra of the zirconium fractions showed contamination. However, this y-ray contamination was always sufficiently low in energy not t o interfere
Analytical Results from Quantitative Elution Method
Relative Atoms/Ml. Standard counting procedure
1.14 1.14 1.14 1.14f0.00 7.03 7.26 6.70 6.99 f 0.30 8.66 8.64 8.70 8 . 6 7 f 0.03 1.24 1.24 1.24 1.24 f 0.00 2.23 2.31 2.28 2.27 f 0.04 1.20 1.23 1.21 1 . 2 1 f 0.02 1.45 1.45 1.44 1 . 4 5 f 0.01
Moos, Relative Fissions/Ml. Standard y counting procedure 1.15 9.47 9.68 1.14 9.79 9.78 1.17 9.79 1 . 1 5 f 0 . 0 2 9.68=l=OO.21 9 . 7 3 A 0 . 0 5 7.07 7.01 7.04 f 0.03 8.70 8.60 8.65 8.65 f 0.05 1.25 1.26 1.25 f 0.01
1.43 1.48 1 . 4 5 f 0.03
from
with measurement of the 0.72-n1.e.v. zirconium-95 peak. The pulses are a direct function of the y-ray activity, so that if the analyzer is calibrated with a known sample of zirconium-95, the summation of the pulses in the peak is a measure of the zirconium-95 activity. This applied to any zirconium-97 which was present in samples obtained early after bombardment. Neptunium. The neptunium-239 fractions had no detectable impurities in their y-ray spectra and decay nieasurements over several half lives showed less than 1% of other activity present. Niobium and Plutonium. Less than 1% of the neptunium-239 activity will usually be found in the niobium eluate but will not interfere Kith t h e measurement of t h e niobium95 0.76-m.e.v. y-ray n-ith the 256channel anal>-zer, as evplained for zirconium-95. Any plutonium isotope will be found in this fraction and can be determined in any suitable manner after the desired neptunium data have been obtained. These arc usually long-lived a-ray emitters. Uranium. T h e uranium fractions all contained the tellurium-l32(1V) activity, which has approximately t h e same high fission yield as molybdenum-99. Unless the uranium-237molybdenum-99 ratio is large, t h e tellurium-132 and subsequent iodine132 daughter growth will make i t very impractical t o determine t h e uranium-237 either by direct y-ray counting or by its spectrum. Because
1.48 1.46 1.47 1.47 f 0.01 1.35 1.25 1.28 1.29 f 0.06 5.18 5.30 5.20 5 . 2 3 f 0.07 1.67 1.63 1.65 1.65 f 0.02
Pr,Relative Atoms/Ml. Standard y counting procedure
7,279 7,477 7,137 7,293 i 150
1.49 1.49 1.49 1.49 f 0.00 1.27 1.29
1 . 6 5 f 0.01
3,900 3,774 3,866 3,800 f 100
39,200 29,200 40,400 28,800 41,000 29,800 40;200 f 1000 29;300 f 500 73,000 14,200 72,500 14,500 71,900 14,300 72,500 i 600 14,300 f 200
1.28 f 0.01 5.45 5.52 5.48 f 0.07 1.64 1.66
?-Spectrometer, C.P.M. ZrQ6 NbQ6
3.48 3.48 3.53 3.50 f 0.03
3.50 3.38 3.44 f 0.06
8980 8870 8610 8820
f
170
VOL. 31, NO. 3, MARCH 1959
0
329
the half lives are 77 hours for tellurium132 and lf33 hours for uranium-237, i t is possible to let the former decay so that the latter can be counted. This decay method is practical only if the initial uranium activity is greater than or equal to the technecium activity. The uranium-237 in sample 7 was determined in this manner. An anion exchange separation of tellurium from uranium is now being investigated. Molybdenum. T h e molybdenum99-technecium-99 pair contained no significant y-ray impurity and in most cases was still in equilibrium immediately after elution with 12N nitric acid. Therefore, a n initial y-ray count in the scintillation well counter was sufficient. I n one or two samples a few per cent of the technecium daughter was not in this fraction, and it was necessary to wait 24 hours for the equilibrium measurement.
for sample 6. The precision in the direct method compares favorably with the other results. The uranium-237 determinations by the two methods are within 2%. The zjrconium-95 and niobium-95 counting rates show a precision to about 2y0 for the triplicate values.
ACKNOWLEDGMENT
The author is indebted t o E. C. Freiling and N. E. Ballou for competent advice and Edith Scadden for performing the radiochemical molybdenum analyses.
SUMMARY
The direct sequential elution procedure gives quantitative yields for molybdenum, zirconium, niobium, neptunium, and uranium activities in complex radionuclide mixtures from neutron bombardments of uranium. The y-ray purity of the molybdenum and neptunium is greater than 99%, whereas the contaminants found in the zirconium and niobium fractions can be tolerated by using y-ray spectrometry. The uranium activity is mixed with the tellurium-132-iodine-132 pair and usually requires further purification. The main advantage of the method is reduction in time due to elimination of tracer and carrier addition, pre-ionexchange chemistry, subsequent yield determination, and decay measurements. If a flow rate of 1 ml. per 3 to 5 minutes is maintained, several samples in concentrated hydrochloric acid can be analyzed in about 6 hours. A large fraction of this time can be spent in other work, as the columns require very little attention. Many other fission elements are adsorbed in Dowex 2 from concentrated hydrochloric acid solutions ( 4 ) ; some of these will be investigated for inclusion in the sequential elution procedure.
COMPARISON WITH STANDARD PROCEDURES
The analytical results are given in Table 11. The direct elution data were obtained in triplicate. For comparison the molybdenum-99, uranium-237, and most of the neptunium-239 activities were determined on similar aliquota by standard radiochemical procedures. The zirconium-95 and niobium-% counting rates were obtained by adding the pulses in the channels under the peak in the y-ray spectrum obtained from the 256-channel spectrometer. For neptunium-239 and moIybdenum99 the average relative activities from both procedures agree within l%,except for a 5% difference in the molybdenum
LITERATURE CITED
( I ) Bunney, L. R., Ballou, N. E., Pascual, J., Foti, S. C., A s . 4 ~ .CHEV. 31, 324 (1959). (2) Connally, R. E., Zbid., 28, 1847(1956). (3) Hague, J. L., Broir-n, E. D., Bright, H. A., J . Research Nntl. Bur. Standards 53,261 (1954). (4) Hicks, H. G., Gilbert, R. S., Stevenson, P. C., Hutchin, W. H., Livermore Research Laboratory, Rept. LRL-65 (1953). (5) Huffman, E. H., Lilly, R. C., J . -4m. Chem. SOC.71, 4141 (1949). (6) Ibzd., 73, 2902 (1951). (7) Huffman, E. H., Osnalt, R. L., 'h7illiams, L. A., J . Inorg. & ,I-uclear Chem. 3, 49 (1956). (8) Kraus, K. A., Moore, G. E., J . Am. Chem. SOC.71, 3855 (1949). (9) Zbid., 73, 9 (1951). (10) Ibid., p. 13. (11) ZbLd., p. 2900. (12) Zbid., 77, 1383 (1955). (13) Kraus, K. A., Nelson, F., Moore G. E., Ibad., 77,3972 (1955). (14) PIIeloche, V. E., Preues, -4. F., ANAL.CHEM. 26, 1911 (1954). (15) Wish, L., Rowell, XI., L'. 8. Xaval
Radiological Defense Laboratory, Tech Rept. USNRDL-TR-117 (1956).
RECEIVEDfor review May 12, 1958. Accepted December 15, 1958. Division of Analytical Chemistry, Symposium on Radiochemical .4nalysis, 133rd Meeting, ACS, San Francisco, Calif., -4pril 1958.
Qua nt it at ive Rad io c hemicaI An a lysis by 1on Excha nge Anion Exchange Equilibrations in Phosphoric Acid Solutions E. C. FREILING, JUAN PASCUAL, and A. A. DELUCCHI'
U. S. Naval Radiological Defense laboratory, b The applicability of phosphoric acid solutions to the quantitative anion exchange separation of tellurium from uranium and neptunium has been investigated. The equilibrium distribution coefficients of cesium, strontium, cerium(lll), zirconium(IV), teIIurium(IV), cerium(lV), neptunium(lV), niobium(\/), molybdenum(VI), and uranium(V1) between Dowex 2 resin in the phosphate form and various strengths of phosphoric acid solutions have been determined. These elements fall into three groups. The first, cesium and tellurium(lV), does not favor the resin
330
ANALYTICAL CHEMISTRY
Son Francisco 24, Calif.
I
phase even a t 0.1N phosphoric acid. The group composed of strontium, cerium(lll), and cerium(lV) is weakly adsorbed a t low phosphoric acid conKd < l o ) ; the recentrations (4 maining elements are strongly ad1000). The adsorption sorbed ( K d of all elements studied decreases monotonically with increasing phosphoric acid concentrations. Dilute phosphoric eluents therefore show promise for incorporating tellurium in the sequential scheme of quantitative radiochemical analysis developed by
YEIRS anion exchange resin equilibration studies in pure and mixed hydrochloric, hydrofluoric, nitric, and sulfuric acids have been fruitful sources of potential and actual radiochemical separations ( I , 2, 4 ) . Kraus and ?\Telson (2) point out the relatively little attention given to phosphate media, although Marcus has described studies of the Do\Vex 1-XlO-uranyl phosphate system (3). This conimuni-
Wish.
Calif.
x RECEST
I Present address, Department of Chemistry, Vniversity of California, Berkeley 4,
