ANALYTICAL CHEMISTRY
1780
Table IV.
Micro Determination of Carbon and Hydrogen in Gaseous Vaterials
found in the Genetron 150 sample indicate that it contxins an imp:irity mith a lower fluorine content. LITERATURE CITED
hlateiial Isobiitanea
Freon I l . I D , C
Obsd. presT ~ ~ Carbon, ~ HJ d r o w n . tvt % volume. sure, perature Wt % MI h l m . Hp C Calcd. Found Calcd. Found 2 199 2.208 2 252
2 238 2.321 2 175
Genetron l50b 2 175 2 193 2 138
768 771 770
7633.3 768 5 767.5
770 7639 7G8.5
24.7 23.0 25.7
23.0 23.0 24 0
23.2 23 7
82.6G
83.14 82.92 83.10
17 34
17.51 17.44 17.45
4v. 8 3 . 0 5
Av.
17.47
0.65C
14.05
14.09 13.90 13.88
0.00
Av.
13 96
hr.
0 05
37 52
37 05 36 93 37.18
9 I3
3.66 3.38 3 30
Av.
37 05
Av.
3.45
23.5
0 05 0 05
" Carbon and hydrogen values ca1,culated using density of 6.482 CII. ft./lb. a t 1 atm. and 70' F. ( 1 3 ) . Corrections for deviations froin perfect gas law negligible for these small temperature differences. 6 Corrections for dewations from perfect gas law ( I ) made in calculation of weight per cent carbon and hydrogen,. c High value may be due to inoistiire in gas buret; excluded froni a\.erage.
(1) Beattie, J. A., Cheni. Rem. 44, 174 (1949). (2) Belcher, R., Gouldin, R., Mikrochemie ver. Mikrochim. Acta 36-37, 679 (1951). (3) Belcher, R., Ingram, G., Anal. Chim. Acta 4, 401 (1950). Illinois State Geol. SurTey. Rept. (4) Clark, H. S., Rees, 0. W., Invest. No. 169 (1954). ( 5 ) Cross, C. K . , Wright, G. F., ASAL.CHEM.26, 886 (1954). (6) Duval, Cl., "Inorganic Thermogravimetric Analysis," p. 102, Elsevier, Kew York, 1953. (7) Fischer, F. O., ANAL. CHEX 21, 827 (1949). (8) Huckabay, W.B., Welch, E. T., Rletler, A. V., Ibid., 19, 154 (194i). (9) Kirsten, W,, Ibid., 25, 74 (1953). (10) Marion, L., Ledingham, A. E., IXD.ESG. CHEY.,-4x.a~.ED.13, 269 (1941). (11) Morgan, G. T., Tunstall, R. B., J . Chem. Soc. (London) 125, 1963 (1924). (12) Siederl, J. B., Siederl, V., "Organic Quantitative LIicro hnalysis," 2nd ed., pp. 101-50, Wiley, Xew York, 1942. (13) Perry, J. H., "Chemical Engineer's Handbook," 3rd ed., p. 264, McGraw-Hill, Sew York, 1950. (14) Taylor, W. AI., E. I. du Pont de Kemours 8: Co., Inc., Wil-
niington, Del., private communication.
for these compounds and for isobutane are shown in Table Is'. The .ample of Freon 114 testec. appears to be piire, while the carbon and hydrogen valiies and the ratio of carbon to hydrogen
(15) Throckmorton, W.H.. Hutton, G. H., ; ~ N A L . CHEM.24, 2003 (1952). (16) Youden, W.J., "Statistical Methods for Chemists," Chap. 2 . Wiley, Few York, 1951. RECEIVED for review January 18, 1956.
Accepted June 16, 1956.
Precipitation of Actinium Oxalate from Homogeneous Solution MURRELL L. SALUTSKY' and H. W. KIRBY M o u n d Laboratory, Miamisburg,
Ohio
Actinium separated by ion exchange from neutronirradiated radium was found to contain nonradioactive impurities, mostly iron and aluminum. These impurities interfered with the reduction of actinium to the metal. A method is described for purifying actinium by oxalate precipitation from homogeneous solution. Yields of 97% or more were obtained. The solubility of actinium oxalate in 0.1N nitric acid-0.5N oxalic acid solution was 0.024 mg. per ml.
A
CTIYIURI can be synthesized by the neutron irradiation of radium and separated from the radium by ion exchange on Dotvex-50 resin ( 5 ) . However, nonradioactive impurities, chiefly iron and aluminum, are introduced from the resin. These impurities, which may constitute an appreciable percentage of the product, interfere Tvith the reduction of actinium to the metal (1.4). Oxalate precipitation from weakly acid solution has been used to separate lanthanum and the rare earths from iron, aluminum, and many other elements ( 1 5 ) . Several investigators ( 4 ) have coprecipitated tracer quantities of actinium n i t h lanthanum oxalate, but only a few micrograms of actinium has been precipitated as oxalate without lanthanum carrier (2j. I n this paper the carrier-free precipitation of macro quantities of actinium oxalate is discussed. Precipitation from homogeneous solution 1 Present address, Research Department, Inorganic Chemicals Division, Xlonsanto Chemical Co., Xicholas Road, Dayton, Ohio.
(3, 1 6 ) was effected by the hydrolysis of dimethyl oxalate to produce oxalate ions uniformly within the solution. PROCEDURE
The actinium fraction obtained from the ion exchange column was evaporated in a small filter-beaker (11) until a precipitate began to form. Sufficient xater was added to dissolve the precipitate. The pH was adjusted to 1 t o 2 by the dropwise addition of 3-V ammonium hydroxide until 1 drop formed a hydroxide precipitate. Then 1 to 20 nitric acid was added dropwise until the hydroxide dissolved. Water was added until the actinium concentration was 0.5 curie (about 7 mg.) per ml., followed by the addition of three times the stoichiometric amount of dimethyl oxalate dissolved in the minimum quantity of methanol. (The dimethyl oxalate was recrystallized from methanol, prior t o its use, t o remove possible oxalic acid impurity.) The solution was stirred and heated a t 60" t o 70" C. The dimethyl oxalate slowly hydrolyzed and, after a few minutes, the solution became turbid with actinium oxalate. The mixture was digested with stirring a t 60" t o 70" C . for 30 minutes and then stirred at room temperature for an additional 90 minutes. The oxalate was filtered and washed with 1yo oxalic acid solution. The oxalate was decomposed with a few drops of red fuming nitric acid. Occasionally actinium nitrate was produced. It dissolved upon the addition of a few drops of water and, thus, could be differentiated from the oxalate. The nitrate solution was evaporated t o dryness to remove the excess nitric acid. The resulting actinium nitrate n-as dissolved in water and the actinium concentration again adjusted t o 0.5 curie per ml. A second oxalate precipitation was made by the procedure described above. The actinium oxalate obtained after the second precipitation was also converted t o the nitrate. The nitrate was dissolved in the minimum quantity of water, transferred t o a small, weighed platinum crucible, and carefully evaporated t o dryness under an infrared lamp to remove eycess
V O L U M E 2 8 , N O . 11, N O V E M B E R 1 9 5 6
1781
nitric acid. The nitratc was dissolved in 1 to 2 ml. of water. T o this solution WVBS added an excess of 5% oxalic acid. The mixture was carefully evaporated to dryness under an infrared lamp. The residue was dried a t 200" C. in a small muffle furnace for 30 minutes and then ignited at 900" C. for 90 minutes. The platinum crucible was cooled to room temperature and weighed, and the weight of actinium oxide was calculated. .As actinium is a highly radioactive and biologically dangerous material, it was necaessary to carry out this work in a well vent,ilated dry box. The glassware, which became brown and crazed because of the intense radiation, was handled through glove ports and brhind 2 inches of lend shielding. RESULTS AND DISCUSSIOS
.ictinum nitratc was converted to osalate prior to ignition t o t h r oxide, to prevent spattering during ignition. Lanthanum nitrate, for example, melts prior to decomposition and some Lanthanum can be lost through spattering upon conversion of the nit,rate to the oxide. \Then precipitated from homogeneous solution, the actinium ox:il:tte wiis a very dense xhite crystalline material. The osidc obtained upon t h r ignition of the purified oxalate was also a nhitc compound, whirh glowed with a bright white luminescrnce viFiblr even in a lighted room. The filt,rates from the oxalate precipitations were analyzcd r:itiiochemically for actinium ( 9 ) . The method consisted of a doiible thorium iod:tte precipitation in 5 t.o 6.V nitric acid with thorium carrier to remove thorium-227, followed by a double b:trirrm nitrate precipitat,ion in 80% nitric acid with barium carrier t.o remove radium-223. Bliquot,s of the solution containing the freshly purified act,inium were mounted on stainless steel disks and alpha-counted a day or more aft,er purification. The roiints were corrected for t,he groil-th of actinium decay products ( 8 ) . The actinium concentration in t,he filtrates was calculated from these corrected alpha count,s, assuming a 22.0-year half life ( 7 ) . The results of the analyses of the filtrates from two actinium purificat,ions are shown in Table I. The actinium originally in s:rmple 1 (27.5 mg.) was det,ermined by a calorimetric met,hod (12). S o original calorimetric measurement was made on sample 2. The actinium recovered as oxide in each case was determined gravimetrically. The resu1t.s indicate a high recovery of actinium by the oxalate precipit,ation method. The loss of actinium in the first, oxalate filtrate was several times greater than that in the wcond filtrate. The high concentration of impurity present during t h e first precipitation apparently increased the sohihilit!. of uctiniuni oxalate.
Table I.
Purification of ;ictinium by the Oxalate >\lethod Fraction
.Ictiniiim oxide First oxalate filtrate Second oxalate filtrate
.4ctiniirm ~JIg. 26 5 0.4 0.06
__
Total Original
27.0 27 5
Actinium oxide First oxalate filtratr Second oxalate filtrate
43.5 0.8 0.1 ~
a
Total Original Jlole ratio.
Iron Jlg.
R
Sample 1 96.b Si1 1.5 0.60 0.2 0 02
97 3
"/c
__
08
0.62 (Fe/Ac = l/lO)Q
Sample 2 98 0 Si1 1.8 4 10 0.2 0 03
.. 99 I
I n addition t o iron, aluminum was detected by spot tests ( 1 ) in the filtrates from the first oxalate precipitations but not in those from the second. dddition of barium gave a test for sulfate in the first oxalate filtrates. The sulfate probably resulted from the radiation decomposition of the ion exchange resin. The solubility of actinium oxalate can be est.imated from the results of the analyses of the second oxalate filtrates. The solution had a p H of 1.2 and was approximately 0.LV oxalic acid. For the two separate actinium purifications the second oxalate filtrates contained 0.0149 and 0.0158 mg. of actinium per nil., respectively. The solubilit,y of actinium oxalate calculated on t,he basis of the anhydrous compound was 0.024 mg. per ml. This value compares favorably with solubility values repoi,ted by Sarver and Brinton ( I S ) for lanthanum oxalate in similar solutions. For example, as shown in Table 11, the solubility of lanthanum oxalate in I S hydrochloric a~id-0.5~V osalic acid was reported as 0.06 mg. per ml. I n 0.LV mineral acid-0.5S o d i c acid, the soluhility of lanthanum oxalate would be less than this value. It is probable that the solitbilities of actinium and lanthanum oxalates do not differ greatly. Other estimated values for the solubility of actinium oxalate are shown in Table 11. Wever (6) estimated the solubility of actinium oxalate in 0.1A- hydrochloric acid by tracer disfribution studies with rate earth oxalates. The value of 0.5 mg. per ml. indicated that actinium oxalate was more soluble than lanthanum oxalate (0.21 mg. per ml.). I n either case, the addition of oxalic acid decreased the soluhilit?..
Table 11.
Solubilities of Actinium and Lanthanum Oxalates .IC?(
Sol\ e n t 0.lA' HSOs. 0.5.Y HvC204 1.V HC1, 0.5,\- H2Cz04 0.1.V HC1 0.05.V IICI. 0.5.Y (SHa)zCzOn 0.03.Y HC1, 0.7.1. HzCvOa
C204) 7 ,
Jlg./Ml. 0,024 0:5 (6, 1 0 . 2 (2) > O . 14 (2)
Lar(CvOd1, Jlg./-M!.
o oi'(i3) 0 21 (13)
.... ....
I n the preparation of microgram quantities of actinium oxalate for x-ray samples, Fried, Hagemann, and Zachariasen ( 2 ) obtained a white dense precipitate when 50 pl. of 1 N ammonium oxalate solution was added to 10 y of actinium in anequal volume of 0.LV hydrochloric acid, but no visible precipitat,e when 100 p l . of saturated oxalic acid solution was added to 10 y of actinium in 50 rl. of 0.1-Vhydrochloric acid. The latter case woiild indicate a rather high solubility for actinium oxalate, approximately one order of magnitude higher than the solubility found in the present 11-ork. However, in the precipitation of very $mall quantities of lanthanum and rare earth osalat,es from mineral arid solutions there is a tendency toward either supersat,urntion or microcrystalline formation. If this is also the case in t8heprecipitation of microgram quantities of actinium oxalate, a solubility higher t,han the actual solubility would be ohserved. This possible source of error was eliminated in the present work by the precipitation of act,inilim oxalate in macro quantity from homogeneous solution.
~
44.4
..
4.13 (Fe/Ac = 4/10)=
Polarographic determination of iron in the filtrates ( I O ) shon ed that 97% or more of the iron was removed by a single oxalate precipitation (Table I). The mole ratio of iron t o actinium originally in the first sample x a s 1t o 10 and in the second, 4 to 10.
ACKNOWLEDGMENT
The authors wish to thank Carlyle E. Shoemaker and Kenneth Jordan for the polarographic and calorimetric analyses. LITERATURE CITED (1) FeAgl, F.. "Qualitative dnalysis by Spot Tests," 3rd ed.. pp. 142i , Elsevier, Kew York, 1946. ( 2 ) Fried, S.,Hagemann, F.. Zachariaien, W'. H., J . 9 ~ 7 Chem. . SOC. 72, 771 (1950).
1782
ANALYTICAL CHEMISTRY
(3) Gordon, L., Brandt, R. H., Quill, L. L., Salutsky, 11.L., AKAL. CHEM.23, 1811 (1951). (4)
(5) (6) (7)
(8) (9)
(10)
Hagemann, F. T., “The Actinide Elements,” Natl. Nuclear Energy Ser., IV-l4A, G. T. Seaborg and J. J. Katz, eds., pp. 14-44, LIcGraw-Hill, Sew York, 1954. HaFemann, F., Bndrews, H. C., U. S.Atomic Energy Commission, ANL-4215 (Oct. 18, 1948). Hahn, O., “Applied Radiochemistry,” pp. 89-90, Cornel1 Cniversity Press, Ithaca, X , Y . , 1936. Hollander, J. AI., Leininger, R. F., P h w . Rea. 80, 915 (1950). Kirby, H. W., AI&L. CHEM.26, 1063 (1954). Kirby, H. W., U. S. Atomic Energy Commission MLM-773 (Nov. 20, 1952) (classified). Kolthoff, I. M., Lingane, J. J., “Polarography,” pp. 475-80, Interscience, Kew York, 1952.
(11) Salutsky, RI. L., Kirby, H. W., A 4 s a CHEM. ~. 26, 1140 (1954). (12) Sanielevici, A. C., J . chim. p h y s . 33, 785 (1936). (13) Sarver, L. A., Brinton, P. H. M.-P., J . Am. Chem. SOC.49, 943 (1927). (14) Stites, J. G., Salutsky, AI. L., Stone, B. D., Ibid., 77, 237 (1955). (15) Vickery, R. C., “Chemistry of the Lanthanons,” pp. 182-96, Academic Press, Sew York, 1953. (16) Willard, H. H., Gordon, L., ANAL.CHEM.20, 165 (1948).
RECEIVED for review February 15, 1956. Accepted July 25, 1956. Division of Analytical Chemistry, 129th Meeting, ACS, Dallas, Tex., April 1956. Mound Laboratory is operated b y Monsanto Chemical Co. for the U. S . Atomic Energy Comrnisrion under Contract No. AT-33-1-GEN-53.
Radiochemical Determination of Phosphorus-32 W. B. SILKER Hanford Atomic Products Operation, General Electric Co, Richland, Wash.
A method for the radiochemical determination of phosphorus-32 in reactor cooling water is based on solvent extraction of phosphorus as molybdophosphoric acid. After sorption of radioarsenic on cupric sulfide and exclusion of radiosilicon by extraction from high acid concentration, radiochemically pure phosphorus-32 is extracted with a 10% solution of 1-butanol in diethyl ether. The method is rapid, accurate, and reproducible; 86.6% of the phosphorus-32 is recovered by a single extraction.
I
A
METHOD was required for the separation and determination of phosphorus-32 from reactor effluent water, a solu-
tion containing mixed activation products and fission products. Phosphorus-32 is a pure beta emitter which decays with a 14.3day half life. Radiophosphorus contributes about 0.4% of the gross beta activity of this waste stream, the principal constituents of which are arsenic-76, copper-64, manganese-56, silicon-31, and sodium-24 ( 2 ) . Requirements stipulated that analysis should be completed within 8 hours after sampling. Precipitation of benzidine phosphate or bismuth phosphate as recommended by Hahn and Anderson ( 1 ) for the radiochemical determination of phosphorus-32 was not feasible, because of coprecipitation of contaminants. The classical ammonium molybdophosphate precipitation likewise proved unsatisfactory, owing to considerable contamination in the final product. Formation of molybdophosphoric acid and subsequent reduction to molybdenum blue have been applied for the colorimetric determination of phosphate ion in water and other materials. Solvent extraction of molybdophosphoric acid with 1-butanol eliminates all interferences except arsenate, silicate, and germanate (4). The interference from germanate ions is of no consequence, as no significant amounts of the radioisotopes of germanium are present in reactor effluent water. Radioactive silicon-31 ( Tl/2 = 2.6 hours) and arsenic-76 ( Tl,z = 26.8 hours), both beta-emitters, are present. The specific activities of these two isotopes are 10 to 100 times greater than phosphorus-32. Measures are therefore required to remove these interferences. The low distribution coefficient of molybdosilicic acid into 1butanol from an aqueous medium greater than IN in sulfuric acid has been shown (4). By extraction of molybdophosphoric acid from 1.3N sulfuric acid, silicon isotopes were easily eliminated. Removal of arsenic from phosphoric acid solutions by sorption on stannous sulfide was reported by Shirasaki and Rluroya ( 3 ) . Because of immediate unavailability of stannous
sulfide, a search of available metallic sulfides indicated that the properties of cupric sulfide were compatible with the process, and it was selected as the sorption agent. EXPERIMENTAL
A sorption bed was prepared by placing an aqueous slurry of powdered cupric sulfide over a mat of glass wool and asbestos fibers. The bed was contained in a section of 30-mm. borosilicate glass tubing which was reduced a t the outlet to a 2-mm. stopcock. The liquid was removed by suction, care being taken to keep the liquid level above the level of the bed. The bed was then washed with water until soluble copper salts were no longer visible in the column effluent. .4 cupric sulfide bed, ,prepared from either freshly precipitated or commercially available material (Baker and Adamson, Lot 14R), was found to remove radioarsenic from 0.05N hydrochloric acid solution. It was necessary to maintain arsenic in the arsenite form to assure its removal. Any arsenate ion was therefore reduced with sodium thiosulfate preliminary to sorption on the bed. The removal efficiency of radioarsenic from reactor effluent and spiked tap water samples was measured by analyzing the bed effluent for arsenic-76. I n all cases more than 98.5% of the arsenic content of the influent was retained by the bed. T o determine if loss of radiophosphorus was occurring on the copper sulfide, a phosphorus-32 spiked solution was passed through a 5 sq. cm. X 2 cm. bed. The activity of an aliquot of the effluent was measured with an end-window Geiger-Muller counter and was found to contain the same concentration of radiophosphorus as an equal portion of the influent solution. I n addition, after washing with water, an ali uot of the bed was dried and the contained activity measured. %his measurement shoFed that less than 0.1% of the radiophosphorus content of the influent was present on the total bed. The use of diethyl ether as a diluent for 1-butanol was initiated to expedite sample preparation during the evaporation of the solvent. S o study was made to determine the optimum concentration of 1-butanol in diethyl ether. The concentration reported was satisfactory for the intended purpose. Exclusion of silicon-31 by extraction from 1.3N sulfuric acid was tested by measuring the decay of the final product. More than 99% of radiosilicon was removed from samples of reactor cooling water. PROCEDURE
A 400-ml. sample of reactor effluent water was made 0.05N in hydrochloric acid and heated to boiling, and 1 ml. of 20% sodium thiosulfate solution was added. After standing for 5 minutes the solution was passed a t a rate of 20 to 30 ml. per minute through a 5 sq. cm. X 2 cm. bed of cupric sulfide supported on a mat of asbestos. The first 100 ml. of column effluent was discarded. Two 100-ml. aliquots of the remainder were then analyzed. After
