(3) Beck, G., Anal. Chin&.Acta 1, 69 (1947). (4) Beck, G., Hell’. Chim. Acta 29, 506 (1946). (5) Craig, K. A., Chandlee, G. C., J . Am. Chem. SOC.56, 1278 (1934). (6) D o h , D., Draganic, Z., Bull. Inst. Nuclear Sci. “Boris Kidrich” 2, 77 (1953). (7) Emi, K., Hayami, T., Nippon Kagaku Zasshi 76, 1291 (1955). 18) . , Fassel. V. A , , Heidel. R. H.. E. S. Atomic Energy Comm., ISC-313’(1954). (9) Fisher, S., U. S. Atomic Energy Comm., RMO-2530 (1954). (10) Ibid., RMO-2531 (1954).
(11) Fisher, s., Kunin, R., ANAL. CHEK 29,400 (1957). 1121 Hecht. F.. Korkisch. J.. Patzak. ’ R., Thiaid, A., Mikrochim. Acta 1283 (1956). (13) Hure, J., Saint James-Schonberg, R., Anal. Chim. Acta 9,415 (1953). (14) Ishibashi, M., Higashi, S., Japan dnaZyst 4, 14 (1955). (15) Ibid., 5, 135 (1956). (16) Jackson, D. E., U. S. Atomic Energy Comm., NP-1800(1950). (17) Kuznetzov, V. I., Compt. rend. acad. sci. U.R.S.S. 31, 898 (1941). (18) Kuznetzov, V. I., Zhur. Anal. Khim. 7 , 326 (1952).
(19) Kuznetzov, V. I., Budanova, L. M., Matrosova, T. V., Zavodskava Lab. 22, 406 (1956): 120) Moeller. T.. Tecotzkv. M..’ J . Am. ‘ dhem. S O C . ’ ~ ~’2649 , (i955j. (21) Seim, H. J., Morris, R. J., Frew, D. w., ANAL.CHEM. 29,443 (1957). (231 Susic. M. V.. Bull. Inst. Nuclear Sci. ’ ‘%oris Kidrich’; 7 , 35 (1957). (23) Teicher, H., Gordon, L., ANAL. C.IEM. 23,930 (1951). RECEIVED for review November 22, 1957. Acccmpted June 3, 1958. Contribution No. 575. Work performed in Ames Laboratory,of the U. S. Atomic Energy Commission.
Separation of Uranium from Bismuth by Anion Exchange Resins GURUPADA BANERJEE and ARNO
H. A. HEYN
Department o f Chemistry, Boston University, Boston 7 5, Mass.
b A method for the ready separation of trace amounts of uranium from large excess of bismuth allows for subsequent determination of uranium. At p H between l .O and l .5 the sulfate complex of uranium(V1) is quantitatively retained by a quaternary amine-type anion exchange resin while the cationic bismuth ion passes through the column. Uranium can then b e eluted for analysis by dilute perchloric acid. The method can b e used for the separation of microgram quantities of uranium from bismuth, permitting the routine determination of uranium.
B
of the growing interest in the liquid metal fuel reactor (LAIFR) systems (8), using alloys of uranium in bismuth as the fuel, quantitative separation of uranium from bismuth has attracted the attention of workers in the analytical field. Even trace amounts of bismuth interfere with most known methods for the microdetermination of uranium. As bismuth nitrate is also extracted by ether in the conventional ether-extraction procedure (9) for uranium, the factors which are favorable for the extraction of trace amounts of uranium from large excess of bismuth have been shown by the authors (5). Although extraction with acetylacetone in presence of (ethylenedinitri1o)tetraacetic acid, followed by polarographic estimation, has been utilized b y Krishen and Freiser (7‘) for the separation of uranium from bismuth, the method suggested in this work is more convenient 2nd rapid. The precipitation of bismuth oxychloride on ion exchange columns has also been suggested ECAUSE
for the separation af bismuth and thorium (10). but the method does not appear to be promising for the separation of uranium and bismuth when the latter constituent is large. Stoner and Finston (16)have recentlyshown that homogeneous precipitation, using thioacetamide, offers a clear-cut separation of bismuth. Fisher and Kunin (5) developed a procedure for the separation of uranium from iron, vanadium, and other cations based on the adsorption of uranium(T’1) from dilute sulfuric acid solutions by anion exchange resins. This method was first described in the classified literature [see references in (S)]. Seim, Morris, and Frew (11) adapted the Fisher and Kunin method for routine uranium-ore analysis. Kraus and Kelson (6) reported studies on the adsorption of uranium(V1) in sulfuric acid. Arnfelt (1) independently developed a method for the rapid determination of uranium based on the same principle. Susic (13) used Dotvex-1 for separating uranium from divalent zinc, nickel, manganese, cadmium, cobalt, iron, and copper and also from cerium and cesium Banks and coworkers (6) applied the same principle t o the separation of uranium and iron from rare earths to prevent their interference in the analysis of rare earths. The aim of the work reported here was t o develop a method for the rapid and clean separation of trace amounts of uranium from a large excess of bismuth. The anion exchange method of Fisher and Kunin (3) appeared to offer favorable conditions for this separation, and the present paper reports an adaptation of their method. Ion exchange techniques appeared
c
EiOC 1
I
t
j 2 E
€01
0 E
.c
40-
E 0 c 0
a s? 20-
i
OO
IO
20
30
Sulfuric acid concentration, ml,conc. acid per 100ml.
Figure 1 . Effect of sulfuric acid concentpation on retention of 1000 y of uranium
particularly attractive because of the possibility of using remote handling techiiques for “hot” samples. APPARATUS AND REAGENT
Tubes 9.5 mm. in diameter containing 1 cm, of glass wool in the lower end and equipped with stoppers were used t o contain the resin. T h e rate of flow of solutions through the tube was regulated b y adjusting the stopper. Small separatory funnels were attached to the top of the column to feed the sample and the reagents. VOL 30, NO. 1 1 , NOVEMBER 1958
1795
Beckman Model DU spectrophotometer equipped with photomultiplier attachment using 1-cm. path length cells and Beckman Model G glass electrode p H meter were used for absorbance and pH measurements, respectively. A weighed quantity of uranyl nitrate, LTOz(NO~)~. 6H20, mas dissolved in distilled water and made up t o volume to give a stock solution containing 10 mg. of uranium per ml. The uranium content was determined grarimetrically. Solutions of greater dilution were made from the stock solution as required. All other reagents Ivere either Baker analyzed reagent grade chemicals or Merck’s reagent grade chemicals. I O N EXCHANGE SEPARATION
The separation of uranium from bismuth is based on the fact that the sulfate complex of uranium(T’1) is quantitatively retained by quaternary aminetype anion exchange resin while the cationic bismuth ions of the solution pass through the resin bed. After the column has been washed several times with dilute sulfuric acid (pH 1 to 1.5) and subsequently with water, uranium is eluted from the resin with dilute perchloric acid (1 to 10) to form a solution suitable for spectrophotometric determination. PROCEDURE
,
d portion of the quaternary aminetype anion exchange resin (Dowex 1X10) of mesh size 100 to 200 was converted to the sulfate form by treating a column of it n i t h 1Oyosulfuric acid, using 5 volumes per volume of resin. This acid-treated resin 11-as washed with distilled water until the effluent was neutral to methyl red. The resin Tvas made free of excess water and stored in a bottle. A 5-ml. portion was used for each analysis. The resin was then poured into the ion exchange column and the bed n-as backwashed with n-ater to remove entrapped air. After the resin had settled, the excess n-ater was drained off to n-ithin 0.1 ml. of the top of the bed brfore the sample was passed through it. Different aliquots of bismuth were taken in 150-ml. beakers and each was digested slowly n-ith a known volume of concentrated sulfuric acid (2 and 5 ml. of acid for 50 and 200 mg. of bismuth, respectively) over a Bunsen flame until the digestion was complete, as indicated by a perfectly white residue. The beaker was then cooled in a n ice bath and the white mass so obtained was dissolved in 65 ml. of water. T o this solution was added a knoll-n aliquot of uranium and the pH was then adjusted to between 1.0 and 1.5 by the dropwise addition of 50% sodium hydroxide. Finally the total volume of the solution was made up to 100 ml. An unknown, such as a bismuth LMFR sample would be digested with sulfuric acid, as above. This solution was then passed through the resin bed at a rate not exceeding 2 ml. per minute. The sample container 1796
ANALYTICAL CHEMISTRY
m l . of HCIO, s o l u t i o n
Figure 2. Effect of perchloric acid concentration on elution of 1000 y of uranium
was then washed first with dilute sulfuric acid (pH 1.0 to 1.5) until the iodide test for bismuth in the effluent was negative, and then with two 10-ml. portions of water a t the same flow rate. Uranium mas then eluted with 40 ml. of 1 to 10 perchloric acid. The eluted solution was evaporated nearly to dryness on a hot plate, the residue was dissolved in a minimum volume of water, and the uranium content of the solution was estimated spectrophotometrically by the standard sodium hydroxide-hydrogen peroxide method (4). The results are shon-n in Table I. For spectrophotometric determination, standard uranium solutions containing 40 nil. of 1 to 10 perchloric acid in each case were used in establishing the calibration curve as well as the reference solutions.
Table I. Determination of Uranium after Separation from Bismuth
Bismuth Present, Mg. 200 50
200 50 200
50
74
Granium,
Deviation y
of
-4dded Found Bverage 1000 1002,999,1002 + O . 1 1000.998.1002 , - - - , - - - - 0.0 -0.4 200 i99,2oi,m 0.0 200 200,199,201 -1 0 100 99,98,100 0 0 100 101,99,100 -1 . 2 50 49.2.49.0,50.0 50 49.5;49.4;49.5 -1.1
of the mixture is held up by the resin, and it may be adopted for the separation of mixtures of a wide range of bismuth contents by varying the volume of the sample, the concentration of sulfuric acid, and the size of the resin bed. Mixtures containing less than 50 y of uranium may also be analyzed by decreasing the volume of the resin and of the perchloric acid. Because bismuth sulfate decomposes in water, forming a basic salt, the volume and the temperature of the sample solution should be rigorously controlled. For example, 200 mg. of bismuth cannot be kept in solution as sulfate between p H 1.0 and 1.5 if the sample volume exceeds 100 ml. and the adjustment of pH is not made by cooling the sample in ice. Even so, the sample adjusted to pH 1.0 to 1.5 must be analyzed within 2 hours, else hydrolysis occurs. The degree of retention of the sulfate complex of uranium(V1) on the anion exchange resin from a solution containing sulfate ion is dependent not only on the hydrogen ion concentration but also on the concentration of sulfate ( I ) . Figure 1 s h o m the effect of sulfuric acid present in the sample solution containing 1000 y of uranium on the retention of uranium studied under the conditions of the experiments. It seems evident that 1000 y of uranium(V1) is quantitatively removed from a solution containing up to 5 ml. of concentrated sulfuric acid in a total volume of 100 ml. However, 5 ml. of concentrated sulfuric acid is the minimum volume of acid required to keep 200 mg. of bismuth in solution as sulfate within the pH range 1 to 1.5 in a total volume of 100 ml. Uranium can be separated from larger amounts of bismuth by increasing the volume of the sulfuric acid solution: For each 200 mg. of bismuth 100 ml. of a solution containing 5 nil. of concentrated sulfuric acid must be used. Previous work has shown (1) that for the elution with hydrochloric acid, the elution of uranium is incomplete, because of the formation of the UO&ld-2 complex when the concentration of the acid is increased. The use of perchloric acid prevents this difficulty (Figure 2 ) . Figure 2 s h o w that the uranium can be eluted quantitatively with perchloric acid solutions of any strength, if a sufficient volume of the solution is used. ACKNOWLEDGMENT
The authors gratefully acknowledge the financial assistance of the U. S. Atomic Energy Commission in this work.
DISCUSSION OF RESULTS LITERATURE CITED
The method outlined offers several advantages over the others reported in the literature, as the smaller constituent
(1) ALnfelt, A., Acta Chem. Scand. 9, 1484
(1935).
(2) Banks, C. V., Thompson, J. A.,
O’Laughlin, J. IT., ANAL. CHEX 30, 1792 (1958). (3) Fisher, S.,Kunin, R., Zbid., 29, 400 (1967). (4) Grimaldi, F. S., hlay, I., Fletcher, M. H., Titcomb, J., U.S. Geol. Survey, Bull. 1006 (1954). (5) Heyn, A., Banerjee, G., U. S. Atomic Energy Commission, Rept. SYO-7567 (July 1957). (6) Kraus, K. A., Nelson, F., Proc. Intern.
haven Sational Laboratory, Upton, L. I., X. T., private communication. (11) Seim, H. J., Morris, R. J., Frew, D. W., AXAL.CHEM.29, 443 (1957). (12) Stoner, G. A., Finston, H. L., Zbid., 29, 570 (1957). (13) Susic, h1. V., Bull. Znst. Nuclear Sci. “Boris Kidrich” 7, 35 (1957).
Conf. Peaceful Uses of Atomic Energy 7, 113-25 (1955). (7) Krishen, A., Freiser, H., ANAL,CHEM. 29, 288 (1957). (8) Liquid Metal Fuel Reactor, Brookhaven National Laboratories, Rept. BNL 403 (T-88) Lh4FR-13 (January 1957).. (9) Peligot, E., Ann. chim. phys. (3) 5, 1 (1942). (10) Samos, G., Finston, H. L., Brook-
RECEIVEDfor review January 4, 1958. Accepted June 13, 1958.
Anomalous Behavior of gem-Diethers in the Mass Spectrometer R. BRUCE LeBLANC The Dow Chemical Co., Freeport, Tex.
b Acetal gives different mass spectra on a bare tungsten filament and a carOn the bonized tungsten filament. bare filament there is a decomposition according to the equation:
The spectrum obtained is a summation of the spectra of vinyl ethyl ether, ethanol, and acetal. As many as possible of the acetal-type compounds were obtained and checked to see if this type of decomposition is general. All gem-diethers with a phydrogen atom decompose on the bare tungsten filament into alcohols and vinyl ethers. For reliable analysis of these types of compounds in the mass spectrometer, it is recommended that a carbonized filament be used. The extent of carbonization of a filament can be checked by running the spectrum of a compound such as acetal.
CH&H(OC2H6)2 CzHsOH
=
diethers were obtained for checking this phenomenon on the mass spectrometer.
+ CHFCHOC~H~ (1)
The possibility of the decomposition’s occurring in the sample reservoir was eliminated by cleaning all the sample introduction equipment thoroughly and comparing the theoretical sample pressure in the reservoir \T-ith the actual pressure. The theoretical and actual pressures were the same. A new filament was put into the instrument and the spectra of the above compounds were obtained. The filanient was then conditioned with styrene. About 10 nights of conditioning with about 100 niicrons of styrene in the sample reservoir were required to carbonize the filament sufficiently to obtain normal spectra on these compounds. All work was done on a General Elec-
The mass spectrum obtained is the summation of the normal spectra of acetal, ethanol, and vinyl ethyl ether. This reaction should be general for all gemdiethers which have at least one p-hydrogen atom. This phenomenon was discovered when wide discrepancies occurred between results from mass spectrometric and infrared analyses of some samples containing acetal. EXPERIMENTAL
Eight genz-diethers. five orthoesters, one gem-diester, and two cyclic gem-
Table I.
m,’e
Mass Spectra of Acetal, Dimethyl Acetal, and n-Propyl Acetal
Carbonized
Bare
Excess
Vinyl Ether
Alcohol
Vinyl Ethyl Ether ... 80.0 0.9 23
Ethanol ... ... 43.3
Sum
Acetal
N
the mass spectrum of a conipound is considered 8 “fingerprint” of the compound if conditions such as temperature, focus, and type of scanning are held constant. Condition of the filament in the ion source usually does not appreciably alter the cracking pattern of a compound. gem-Diethers (compounds with two alkoxy groups on the same carbon atom) are one class of compounds which do gire different spectra, depending on whether the filament is bare tungsten or carbonized tungsten. The carbonized tungsten filament gives what can be called the normal spectrum of the compound ( I , 2 ) . The bare tungsten filament causes a partial decomposition of the gemdiether into a vinyl ether and a n alcohol. For example, acetal will decompose in the ion source of a mass spectrometer with a new filament according t o the equation: ORMALLT,
73 72 46 45 31
75 59
58
43 32 31
131 87
86 60 59 45 44 31
.
100 3.0 5.3 196 11.4
83.0 49.5 324 296
31.1 100.0 2.2 18 4 1 4 34 5
31.0 100.0 18.7 31 4 14 2 60 3
15.1 100 0.9 0.9 3.7 170 7.7 15.6
15.5 100 67.6 48.7 89.7 317 390 878
100
...
80.0 44.2 128 285 20 Dimethyl acetal Vinyl Methyl Ether
111
250
...
80.0
44.2 134 2jo
hlethanol
...
... 16.5 13 0 12 8 25 8 n-Propyl Acetal
16.5 10 5 2 2 9 2
... 10.6 14.9
16.5 10.5 12.8 24.1
...
...
66.7 47.8 86.0 147 382 862
VOL. 30. NO. 1 1 , NOVEMBER 1958
1797
