Table I.
Effect of Anions on Extraction of Cerium
%
Ce exAnion Millimoles added tracted NOS- 25 >99 sod-2 9 99 95 18 C10,- 10 >99 POI-3 1 >99 3 97 10 (bulky ppt. formed) 63 F3 4 3 [I ml. saturated >99 A1(Ko3)3added] 10 [3 ml. saturated 96 A1(NO3)3added] 27 [9 ml. saturated 97 Al( rV103)3 added] C1120 >99 Fumed with an equal volume of concentrated HN03before extraction. Otherwise, results were low and erratic. Table II.
Extraction of Cerium from Various Matrices
Matrix.
% Ce extracted
Stainless steel-uranium alloy dissolved in HNOa-HClb 98.5 a 1 ml. added. AI1 samples fumed with an equal volume of concentrated HN03 before extraction. Composition was 0.6M U, 0.48M Fe, 0.07M Ni, 0.14M Cr, 2.2.W “03, and 1.5M HCI. The estraction of cerium(1V) into 9 : 1 nitroethane :n-hexane is greater than 98% over the range of 0.2 to 3.7.11 nitric acid and 0.10 to 0.25~11 T P A S (Figures 1 and 2). The mid-
range values were selected for the recommended procedure : Complete extraction is obtained in 1 minute. The effects of common anions on the extraction of cerium, under the conditions of the recommended procedure, are summarized in Table I. Only chloride, which forms a coating of silver chloride on the bivalent silver oxide, and fluoride, which complexes both cerium(1V) and (111), seriously interfere. Chloride is removed by boiling with nitric acid and fluoride is masked with aluminum (Table I). Aluminum, zirconium, and stainless steel components, which are common nuclear fuel cladding and alloying materials, did not interfere (Table 11). The method also has been applied successfully to thorium fuels, on a routine basis. The distributions of 1-day and 2.5-month cooled fission products in the extraction are presented in Figures 3 and 4. Cerium is completely stripped from the organic phase in 1 minute by reducing with a 1% hydrogen peroxide231 hydrochloric acid mixture. Subsequent precipitation as cerous oxalate gives a solid source, desirable for counting, of stoichiometric composition with complete decontamination of the remaining fission products (Figures 3 and 4).
The precipitation of cerous oxalate was more than 99% complete in the p H range of 2 to 5. With a recovery of greater than 98% in the extraction and strip steps, the method can be set up on a nonyield basis. However, in a case such as this, where the final decontamination step results in a stoichiometric precipitate, the yield
determination requires little added time and eliminates the need for quantitative handling throughout the procedure. The completion of each step in the procedure is indicated by a visual change. The method is thus readily adaptable to routine use by nontechnical personnel. The relative standard deviation for a single determination, based on the gross gamma counting of 6 replicated cerium separations for 1-day cooled fission products, was 0.8% and based on duplicate determinations of 6 irradiated thorium fuel samples, was 1.2%. The degree of decontamination obtained in the major steps of the procedure, for 1-day and 2.5-month cooled fission products, is presented in Figures 3 and 4. The time for a single determination is less than 1 hour. LITERATURE CITED
(1) Glendenin, L. E., Flynn, K. F.,
Buchanan, R. F., Steinberg, E. P., ANAL.CHEM.27, 59 (1955). (2) Ma, T. S.,Benedetti-Pichler, A. A,, Ibid., 25, 999 (1953). (3) McCown, J. J., Larsen, R. P., Ibid., 32, 597 (1960). (4) Maeck, W. J., Booman, G. L., Kussy, M. E., Rein, J. E., Ibid., 33, 1775 (1961). ( 5 ) Smith, G. W., Moore, F. L., Ibid., 29, 448 (1957). (6) Yamamura, S. S., Kussy, M. E., Rein, J. E., Ibid., 33, 1655 (1961). RECEIVEDfor review February 5, 1962. Accepted A ril 11, 1962. Division of hnalytical Ehemistry, 142nd Meeting, .4CS, Atlantic City, N. J., September 1962. Work done under Contract At (10-1)-205 to Idaho Operations Office, U. S. Atomic Energy Commission.
Determination of Radiomanganese in Fission Product-Corrosion Product Mixtures S. FREDERIC MARSH,
WILLIAM J. MAECK, and JAMES E. REIN
Atomic Energy Division, Phillips Petroleum A procedure is given for the determination of radiomanganese applicable to samples containing fission products and activated stainless steel corrosion products. The method is based on a double precipitation of manganese dioxide, ferric hydroxide scavenging, oxidation to permanganate with silver(ll), and precipitation of tetraphenylarsonium permanganate. The stoichiometry and thermal stability of the final precipitate were established. The standard deviation of the method is 1.4%.
1408
ANALYTICAL CHEMISTRY
Co., Idaho
M
falls, Idaho
AI~GANESE is
a common contaminant in the coolants of nuclear reactors, being introduced either as an impurity or by the corrosion of stainless steel reactor components and fuel claddings. I n addition to the a d v a t i o n of manganese-55 ( 10070 abundance) to 2.6-hour manganese-56, radiomanganese is produced by the following reactions: Fe54 (n,p) 3fn54, Fe56 (n,p) Mn56, Co69 (n,.) Mn56. It is therefore possible to use radiomanganese as a corrosion rate indicator by careful interpretation of the data. Various process streams of nu-
clear fuel recovery plants, characterized by samples containing a wide variety of fuel matrices and high levels of fission products, also are analyzed for radiomanganese. In general, existing methods for radiomanganese are designed for specific samples. This work aimed to develop a method applicable to a wide variety of samples containing fission products and corrosion product activity. The more promising methods of separation for manganese were investigated. In the distillation of permanganic acid
I
(C,H5),AtMn04
FINAL
ENERGY IN M E V
Figure 1. Distribution of stainless steel activity in method for 1 day cooled sample
from 10M sulfuric acid containing potassium periodate (IO),fission products iodine, tellurium, technetium, and ruthenium codistill. The tetraphenylarsonium ion forms a n extractable complex with permanganate ( 7 ); however, the complex is easily reduced by organic solvents, and other large osyanions, such as pertechnetate and perrhenate, coextract ( 8 ) . Extraction of the permanganate complex of the lower molecular weight tetraalkylammonium salts (6) gave similar results. Solvents of high oxidation stability were characterized by lorn dielectric constant values and hence by inadequate solubility for this ion association complex. Precipitates which have been used for thc gravimetric determination of manganese are manganous sulfide, which requires special treatment to ensure stoicahiometry (4); manganous ammonium phosphate, which is gelatinous, rcquiring long drying periods for stoichiometry and hence usually is ignited to the p!mphosphate (4); and manganous hydroxide and carbonate, neither of \\-hich is suitable for weighing ( 1 ) . In a recent monograph on the radiochemistry of manganese by Leddicotte (41,most of the procedures include a preripitation of hydrated manganese dioxide fur decontamination, and the majority use this precipitate for the yicld determination. Manganese dioxide, when homogeneously precipitated, has been reported (2) to provide the best single-step separation from other elements; however, its use for a yield determination is questionable as Duval (1) reports no region of thermal stability for this compound. Tetraphenylarsonium chloride, in addition t o forming organic-soluble
complexes with oxyanions, has been used as a reagent for the gravimetric determination of technetium and rhenium ( 1 ) . Upon investigation, the permanganate precipitate was crystalline, easily filtered, and thermally stable t o 120' C. After completion of the work reported in this paper, Smith (9) reported use of this precipitate for the determination of radiomanganese after neutron activation of biological material. Combining manganese dioxide precipitations and a n iron hydroxide scavenging at controlled pH, for decontamination, with a final precipitation of tetraphenylarsonium permanganate has given a method for radiomanganese applicable to fission product and radioactive corrosion product samples. EXPERIMENTAL
Apparatus. Tetraphenylarsonium chloride is converted t o t h e hydroxide form in a 250 mm. X 15 m m . ion exchange column with a large reservoir. T h e tetraphenylarsonium permanganate precipitate is filtered on glass fiber filters, type 934-AH (H. Reeve Angel & Co., Clifton, S . J.). Reagents. Reagent grade chemicals were used without purification. Divalent silver oxide (Handy & Harman, New York) was used in t h e solid form. Tetraphenylarsonium chloride (G. F. Smith Chemical Co., Columbus, Ohio) is converted to the hydroxide form as follows: Fill the ion exchange column, fitted with a glass wool support, with a water slurry of Dowex 1 X 8 (50- to 100-mesh) anion exchange resin t o a settled height of 250 mm. Pass 3M sodium hydroxide through the column
until the effluent is free of chloride (by a silver nitrate test). Wash the column with distilled water until the effluent is p H 8 or less (by p H paper test). Dissolve 10 grams of tetraphenylarsonium chloride in 900 ml. of distilled water and pass this solution through the column. Collect the effluent in a 1liter volumetric flask, rinse the column with 50 ml. of distilled water into the flask, and dilute to volume. Manganese Carrier. Dissolve 18.7 grams of manganous sulfate monohydrate in 1 liter of distilled water. Standardize as follow: Pipet a 3-ml. aliquot into a 150-ml. beaker and dilute to 100 ml. with distilled water. Add 1 ml. of 10% ammonium tartrate, 1 ml. of 1J1 hydroxylamine hydrochloride, 1 ml. of ammonium hydroxide, and 3 drops of O.Z'-j& Eriochrome Black T in triethanolamine. Titrate with (ethylenedinitri1o)tetraacetic acid (EDTA) to the blue color change (11). Procedure. Pipet a n aliquot of t h e sample into a 50-ml. test tube, followed by 1 ml. of manganese carrier a n d 1 ml. of concentrated sulfuric acid. H e a t over a burner t o fumes of sulfur trioxide, cool, a n d carefully dilute with 25 ml. of water. Add 1 ml. of 1M sodium bromate a n d h e a t in boiling water for 10 minutes. Centrifuge, discard the supernatant liquid, and wash the precipitate with 10 ml. of 431 nitric acid. Centrifuge and decant the supernatant liquid. Add 6 drops of concentrated hydrochloric acid, 1 ml. of sulfuric acid, and heat over a burner until dissolution is complete. Continue to heat to fumes of sulfur trioxide, cool, and carefully dilute with 25 ml. of water. Add 1 ml. of 10 mg. per nil. ferric nitrate scavenging solution, mix, and add pyridine until the brown color of ferric hydroxide persists. Add a n additional 1 ml. of pyridine and allow the ferric hydroxide t o coagulate. (Heating may be necessary.) Filter through a Whatman No. 40 filter paper or equivalent into a clean 50-ml. test tube. Add 2 ml. of sulfuric acid, 1 ml. of 1M sodium bromate, and heat in boiling water for 10 minutes. Centrifuge and discard the supernatant liquid. Add 6 drops of concentrated hydrochloric acid, 3 ml. of concentrated sulfuric acid, and heat over a burner until dissolution is complete. Continue to heat to fumes of sulfur trioxide. Cool, carefully dilute with 25 ml. of water, add 200 mg. of solid silver monoxide, and swirl the sample for 1 minute. Heat in boiling water until all of the silver oxide has dissolvrd and immediately cool t o room temperature in an ice bath. (Any precipitate present at this point should be centrifuged and discarded.) Add 5 ml. of 1% tetraphenylarsonium hydroxide dropwise while swirling the solution. Filter on a tared glass fiber filter with the aid of a filter chimney. Wash with 10 ml. of 0.5M sulfuric acid and 10 ml. of water. Dry a t 105' C. for 10 minutes and weigh as (C6H&AsMnOa (10.94 weight yo manganese). Gamma count the precipitate using a thallium activated sodium iodide crystal, preferably VOL. 34, NO. 11, OCTOBER 1962
1409
Figure 2. Distribution of fission product activity in method for 2-day cooled sample
I
10
0.50
I00
i
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ENERGY IN M.EV.
coupled to a multichannel pulse height analyzer. RESULTS A N D DISCUSSION
I n this procedure, the initial sulfuric acid fuming expels reducing acids, such as hydrochloric, which mould interfere in the subsequent precipitation of manganese dioxide. The homogeneous precipitation of manganese dioxide, which gives excellent separation from many metal ions, &as selected as the first decontnmination step. For this, Hillebrand et al. ( 2 ) recommend a boiling nitric acidchlorate medium. The use of a dilute sulfuric acid-bromate medium, recommended by Kolthoff and Sandell (S), gave a denser precipitate with less carrying of foreign activity. The separation of activated stainless steel is particularly effective (Figure I), and with fission products, cerium, iodine, technetium, and zirconium were partially carried (Figures 2 and 3). The manganese dioxide is dissolved with a mixture of hydrochloric and sulfuric acids, reducing manganese to the divalent state, Heating to fumes of sulfur trioxide expels the hydrochloric acid, which soould interfere in subseA ferric hydroxide quent steps, scavenging carries those activities not separated by the manganese dioxide precipitation. The conventional technique of precipitating ferric hydroxide with ammonium hydroxide requires control of pH below 7.5 to prevcnt the carrying of manganese(I1). Pyridine, tt base with a p K value of 8.85, was adopted to eliminate the need for this control. After acidification with sulfuric a-id, a second precipitation of manganese dioxide serves to separate the manganese from the residual fission product activity. Silver(I1) was selected for the oxida1410
ANALYTICAL CHEMISTRY
tion of the manganese to permanganate prior to the precipitation of tetraphenylarsonium permanganate. The oxidation is simply made by the addition of solid silver monoxide, then heating. The heating, however, cannot be prolonged as permanganate is reduced by mater at elevated temperatures ( 5 ) . Other ouidants, normally used for this oxidation, are less applicable. Periodate (and iodate formed in the reaction) form insoluble tetraphenylarsonium salts. Sodium bismuthate, being insoluble, would require an additional separation. Permanganate ion is readily reduced by chloride (9). The conversion of tetraphenylarsonium chloride to the
hydroxide form (see Reagents) avoids reduction, ensuring a stoichiometric compound. Because paper filters reduce tetraphenylarsonium permanganate a t drying temperatures, glass fiber filters are used. Smith (9) reports that tetraphenylarsonium permanganate may be dried to constant weight a t 105' C. and that the weight loss is only 9% after 90 hours of drying. The thermogravimetric behavior of the compound was investigated in this laboratory with a Chevenard thermobalance, using the method of Duval ( I ) , with a temperature rate increase of 1.1' C. per minute. Tetraphenylarsonium permanganate exhibits a constant weight plateau between 25' and 120' C., with rapid decomposition occurring a t 142' C. The stoichiometry of the compound was determined by a manganese analysis, based on an EDTA titration method ( I I ) , after a nitric-perchloric acid wet oxidation of the compound. The manganese content of the compound was 10.96%, compared to a theoretical value of 10.94%. The relative standard deviation for a single determination was 1.4y0,based on the gross gamma counting of six replicated separations of 290-day manganese-54 (produced by a n n,p reaction on FeS4)from 6-month cooled stainless steel activity. Figures 1, 2, and 3 present the degree of decontamination obtained in the major steps of the procedure for I-day cooled stainless steel activity, 2-day cooled fission products, and &month cooled fission products. The time for a single determination is 2 hours. The avcrngc recovery is 7 0 to 85%.
PREClPl TATE
w
a (GH,,)4AsMn04 FINAL PRODUCT IO>
I
0 50
L
IO0
I
I50
ENERGY IN hi E V
Figure 3. Distribution of fission product activity in method for 6-month cooled sample
ACKNOWLEDGMENT
The authors express their appreciation to E. M. VanderWall for performing the thermogravimetric analysis.
LITERATURE CITED
(1) Duval,
C., “Inorganic Thermogravimetric .4nalysis,” Elsevier, New York, 1953. (2) Hillebrand, W. F., Lundell, G. E. F., Bright, H. A,, Hoffman, J. I., ‘‘Applied
Inorganic Analysis,” Wiley, Sew York, 1953. (3) Kolthoff, I. M., Sandell, E. B., IND. ENG.CHEM.,ANAL.ED.1, 181 (1929). (4) Leddicotte, G. W., Natl. Acad. Sci.Natl. Res. Council NAS-NS 3020, 1960. (5) Lingane, J. L., Davis, D. G., Anal. Chim.Acta 15,201 (1956). (6) Maeck, W. J., Booman, G. L., Kussy, M. E., Rein, J. E., ANAL.CHEM.33, 1775 (1961). ( 7 ) Matusaek, J. M., Jr., Sugihara, T. T., Zbid., 3 3 , 3 5 (1961). ( 8 ) Morrison, G. H., Freiser, H., “Solvent Extraction in Analytical Chemistry,” chap. 13, Wiley, New York, 1957.
(9) . , Smith,. H.,, AXAL. CHEW 34. 191 (1962). (10) Strickland, J. D. H., Spicer, G., Anal. Chim.Acta 3 , 5 4 3 (1949). (11) Yamamura, S. S., Phillips Petroleum Co.. Idaho Falls, Idaho,. urivate communication, 1962.‘
RECEIVEDfor review May 25, 1962. Accepted August 8, 1962. Division of Analytical Chemistry, 142nd Meeting ACS, Atlantic City, N. J., Se tember 1962. Work performed under 8ontract At( 1@1)-205 to the Idaho Operations Office, U. S. Atomic Energy Commission.
Separation of Iron by Reversed-Phase Chromatography JAMES
5. FRITZ
and C.
E.
HEDRICK
lnstifute for Atomic Research and Department of Chemistry, Iowa State University, Ames, Iowa
b Iron(l1l) can b e separated from many elements b y extraction from 6M to 8M hydrochloric acid, using the technique of reversed-phase chromatography. The extraction is carried out b y passing the aqueous hydrochloric acid mobile phase through a column packed with Haloport-F, a dispersion polymer of tetrafluoroethylene, to which a stationary phase of 2-octanone is sorbed. Fluoride, phosphate, or citrate causes no interference. Traces of iron(l1l) can b e separated quantitatively from high concentrations of copper(1l) or zinc(ll), and traces of titanium(1V) can b e separated from large amounts of iron(lI1).
A
liquid-liquid extraction is useful in analytical chemistry, i t has several limitations. For example, many estractive separations are not complete unless several extractions with fresh solvent are employed. This can be a time-consuming operation. Solvent extractions can be carried out by adsorbing a n organic solvent onto a solid support. A column is then packed with this support, and a n aqueous solution containing solutes to be extracted is passed through the column. As the aqueous phase passes through the column, it constantly comes in contact with fresh organic solvent. Column extraction of this type seems to be equivalent to many batch extractions with portions of fresh solvent. Small (9) has developed a scheme of this type for the extraction of uranium and certain other elements from aqueous solutions. He uses a styrene-divinylbeneeene copolymer t h a t is surfacesulfonated to make the polymer somewhat less hydrophobic. When the resin is soaked in a solvent mixture such as perchloroethylene and tributyl phosphate, i t swells and becomes gellike. LTHOUGH
A column packed with this gel d l quantitatively extract uranium from nitric acid solution containing nitrate as a salting-out agent. We found the extraction of uranium to be complete, but were unable to remove the uranium quantitatively from the column with water. A faint yellowish band always remained which contained about 2 to 7y0of the uranium originally extracted. The only way that we could recover the uranium completely was to destroy the resin with a mixture of nitric and perchloric acids. A few other column extractions of this type h a r e been attempted. Siekierski and Fidelis (3, 8 ) have successfully extracted zirconium and rare earths from a strong aqueous solution of nitric acid. They used a column in which Hyflo-Supercel was the solid support, with tributyl phosphate as the organic solvent on the column. Pierce ( 7 ) extracted small amounts of copper onto a column packed with dithizone on silica gel. During the course of our work, a paper b y Hamlin et al. (5, appeared which described the extraction of uranium using a column packed with Kel-F, a fluorinated organic polymer, and coated with tributyl phosphate as the stationary phase. They gxtracted uranium from 5.5-\if aqueous nitric acid, separated i t from a number of other elements, and reported no difficulty in stripping the uranium from the column following the separation. We tried various solid supports for reversed - phase chromatographic systems. Silica and firebrick were unsatisfactory. Glass microbeads, coated with lauryltrimethylammonium chloride to render the surfaces hydrophobic, were receptive to organic solvents, and proved rather successful. The glass microbeads provided a very thin solvent layer and had excellent packing characteristics. The main
limitation, however, was the extremely low solvent capacity of a column of this type. A column of solvent-coated glass beads may be useful for the extraction of trace amounts of metal ions. Of the solid supports tested, Haloport-F was the best. This is a dispersion polymer of tetrafluoroethylene used mainly for gas chromatography packing. The resin is porous and has a high capacity for solvents, b u t does not swell appreciably in contact with solvents. I n the work reported, the extraction of iron(II1) from strong aqueous solutions of hydrochloric acid, using the technique of reversed-phase chromatography, was studied. Any one of several solvents is satisfactory as the stationary phase for this separation. Isoamyl acetate gave good results, but 2-octanone gave better. Iron(II1) is quantitatively extracted from 6 to 8M hydrochloric acid and can be separated from most other metal ions. Following the separation, the iron(II1) can be quantitatively removed fron the column b y stripping the stationary phase from the support with methanol and ethyl ether. EXPERIMENTAL
Reagents. E a s t m a n practical grade 2-octanone was distilled before use. Haloport-F ( F & M Scientific CO., Newcastle, Del.), a dispersion polymer of tetrafluoroethylene, was used witho u t further treatment. Hydrochloric acid solutions (6M and 8 M ) were prepared and equilibrated with 2-octanone b y moderate shaking for one minute in separatory funnels. The equilibrated solutions were stored under 2-octanone. Iron(II1) perchlorate was prepared b y oxidizing reagent grade ferrous ammonium sulfate with ammonium persulfate and extracting the iron(II1) into 2-octanone from 8M hydrochloric VOL. 34, NO. 1 1, OCTOBER 1962
141 1
