US2653076A - Preparation of carrier-free radioactive phosphorus values - Google Patents

Description

Patented Sept. 22, 1953 PREPARATION OF CARRIER-FREE RADIO- ACTIVE PHOSPHORUS VALUES Waldo E. Colin, Oak Ridge, Tenn., assignor to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application October 7, 1946, Serial No. 701,625

14 Claims.

This invention relates to a method of preparing carrier free radioactive phosphorus. More particularly, this invention relates to a method of separating radioactive phosphorus from neutron irradiated sulfur.

As employed herein, the term activity or its equivalent when employed with reference to a radioactive element is intended to include the radioactive element and compounds thereof. For example, the term phosphorus activity as employed herein is intended to include radioactive phosphorus as well as compounds thereof. Furthermore, the term tracer and the term tracer quantity or their equivalent are employed as definitive of extremely small amounts of radioactive materials. For example, radioactive materials in concentrations of 10- to 10 molar are considered to be tracer quantities. Such extremely small amounts are incapable of identification by ordinary micro analytical methods, and are therefore, generally identified by the radiations emitted therefrom by means of any of the usual devices for radiation detection and determination known to the art. More particularly, for matter of definition, it is to be understood that the terms tracer and trace as used herein to define concentration in either liquid or solid media, denote concentrations of less than the order of milligrams per gram of total media, in accordance with accepted meaning in the art as defined in Hackhs Chemical Dictionary, third edition, edited by Grant, page 683, published by the Blakiston Company, Philadelphia.

Tracer quantities of radioactive phosphorus, generally referred to as phosphorus tracer, are particularly valuable tools for use in biological research and in medical research. In addition, radioactive phosphorus may be employed in the treatment of various diseases such as leukemia.

Various methods have been proposed for the preparation of phosphorus activity among which is the neutron irradiation of sulfur. In accordance with this method, S is subjected to neutron bombardment in a suitable neutronic reactor to produce P in accordance with the following reaction: S (n,p)P While phosphorus activity may be readily produced with the above indicated reaction, a considerable problem is resented in connection with the isolation of the phosphorus activity from the comparatively large mass of inactive sulfur.

While various methods have been proposed for the separation of other activities than phosphorus activity, these methods, whether chemical or physical, are generally concerned with the separation of activities which may be readily .con-

verted to cations in an aqueous solution. For example, zirconium and columbium activity may be separated by means of chromatographic adsorption followed by selective elution or, if desired, may be subjected to appropriate chemical manipulation resulting in the isolation of carrier free activity. However, in the case of phosphorus activity, generally speaking, the activity exists in the form of material which upon dissolution is converted to anions and hence the methods generally employed for separation of tracer elements are inapplicable.

It is accordingly an object of this invention to provide a method of preparing carrier free radioactive phosphorus.

A further object of this invention is the provision of a method of separating phosphorus activity from material containing the same by means of a sequence of steps which are readily carried out by remote control.

Still another object of this invention is the provision of a simple method of separating phOS- phorus activity from material containing the same which may be readily carried out in existing equipment.

These and other objects of this invention will become apparent to the skilled worker in the art upon becoming familiar with the following description.

In accordance with my invention, sulfur is subjected to irradiation in a suitable neutronic reactor to produce a neutron irradiated mass containing phosphorus activity in the form of P Following irradiation, the sulfur is melted and poured into actively boiling, preferably concentrated, acid. Following this addition of sulfur to nitric acid the solution is cooled, whereupon the sulfur, having thus been contacted in molten state with the aqueous nitric acid solution, solidifies, and is separated by suitable means from the remaining liquid. Any suitable means may be employed to accomplish this separation such as dccantation followed by filtration. In this fashion the phosphorus activity is separated from substantially all of the comparatively large mass of inactive and radioactive sulfur.

In accordance with my present invention the phosphorus activity of a phosphate solution, such as that obtained by the above procedure, is carried from solution by means of an insoluble hydroxide precipitate. It is to be understood that the term hydroxide as used herein and in the appended claims signifies the class of basic compounds which includes hydrated oxides in addition to true hydroxides.

Any insoluble metal hydroxide may be emphosphorus activity.

. ployecl to carry the phosphorus activity from a muth, antimonous, stannous, stannic, chromic,

aluminum, lanthanum, cerous, and ceric hydroxides. It is generally desirable to employ a hydroxide which precipitates in a gelatinous form, such as ferric, aluminum, or lanthanum hydroxide. Ferric hydroxide is the preferred carrier of this class.

in order to accomplish the carrying of phosphorus activity in accordance with my invention, it is preferable, prior to making the solution basic with a suitable base, such as sodium hydroxide, ammonium hydroxide, or the like, that I the cation chosen should be incorporated in the solution, after which the addition of the hydroxyl ion results in immediate precipitation of the insoluble hydroxide, thereby carrying down the On the other hand, the source of hydroxyl ions may be added prior to the addition of the cation, so that upon the addition of the cation, the insoluble hydroxide precipitates, carrying down phosphorus activity.

However, it is to be understood that in the case of certain cations, such as the antimonous, stannous, stannic, and chromic ion, with sodium or potassium hydroxide as the base, and the chromic ion with ammonium hydroxide as the base, the resulting hydroxide is soluble in an excess of the base used to effect the precipitation. In such instances, the amount of base used in excess or that required to neutralize the solution must be substantially stoichiometrically equivalent to the amount of cation employed.

The carrying of the phosphorus activity from the solution by means of an insoluble hydroxide in accordance with my invention may also be accomplished by utilizing an insoluble hydroxide precipitated external to the system containing the phosphorus activity, and added to the solution in its already precipitated form.

After introducing the insoluble hydroxide precipitate into the phosphate solution by any of the above procedures the resulting slurry may be digested at room temperature, or at an elevated temperature, preferably with agitation, to insure thorough incorporation of the phosphorus activity in the precipitate. When the preferred carriers are precipitated directly in the phosphate solution, however, digestion of the precipitate will generally not be necessary.

The hydroxide precipitate and its associated phosphorus activity may be separated from the supernatant liquid by any of the common procedures, such as filtration or centrifugation, and the separated precipitate may suitably be washed with water or with a solution of the base employed for the precipitation. The precipitate and its associated phosphorus activity is then dissolved in an acidic aqueous solution, and the cation of the carrier may then be removed from the re-- sulting solution by any suitable procedure such as solvent extraction or cation exchange adsorp tion.

An aqueous inorganic acid soluti n is t e p ferred solvent for the hydroxide precipitate and its associated phosphorus activity. The particular acid to be employed in any case will depend upon the subsequent separation of carrier cation to be effected. Hydrochloric acid and nitric acid are suitable solvents if the carrier cation is to be separated by adsorption on a cation exchange resin such as Amberlite IR-1- a phenol-formaldehyde cation-exchange resin (of. Industrial and Engineering Chemistry, vol. 33, pp. 697-706, 12034212, 1270-1275 (1941); and Handbook of Material Trade Names, Zimmerman and Lavine, p. 28, Industrial Research Service, 1946.). On the other hand, if the carrier cation is to be separated by solvent extraction, the acid should provide the proper anion to form a compound of the carrier which will be soluble in an organic solvent. Thus, hydrochloric acid may be employed to dissolve a ferric hydroxide carrier recipitate and ferric chloride may then be separated from the resulting solution by extraction with a suitable solvent such as isopropyl ether.

My invention may be illustrated by reference to the following specific examples.

Example 1 Approximately 17.85 g, of sulfur which has been subjected to four days neutron irradiation in a uranium pile neutronic reactor at 4300 kw. power level and thereafter aged for fourteen days is melted and poured into boiling concentrated HNO3, and digested. The solution is cooled, whereupon the sulfur solidifies, and the insoluble sulfur is removed by decantation followed by filtration. The nitric acid solution is then evaporated down to near dryness, then taken up in a volume of 25 ml. of water, and sufficient FeCla is added to give 50 mg. of Fe in the solution. Concentrated ammonia is then added to precipitate the iron and the. Fe(OH)a is centrifuged out, dissolved in HCl, and reprecipitated with ammonia. It is then washed in 1 N NHQOH, and dissolved in concentrated HCl. The acid solution is then diluted to 8 N and the iron removed by four extractions with volumes of isopropyl ether equal to the volume of aqueous layer. The remaining acid solution is evaporated down with HNO3 three times, then taken up with 0.01 N HNO3. The final volume is 48 co. and contains 88% of the phosphorus activity.

While ferric chloride has been given as an example of a source of Fe+++, other sources may be employed, such as ferric nitrate, ferric sulphate, and the like.

Example II A nitric acid solution prepared from neutron irradiated sulfur as in Example I is evaporated to near dryness, then taken up in a volume of 25 ml. of water, and mg. of A1013 is added to the solution. Concentrated ammonia is then added to precipitate the aluminum, and the Al(OH)3 is centrifuged out, dissolved in HCl, and reprecipitated with ammonia. It is then washed in 1 N NH-iOH and dissolved in concentrated I-ICl. The acid solution is then diluted to 0.1 N, and the aluminum removed by passing it through a cation exchange resin column containing Amberlite IRr-l (a phenol-formaldehyde cation-exchange resincf. supra) resin as the adsorber. Substantially all of the aluminum is adsorbed by the resin, and remains in the column, while the acid solution containing phosphorus activity passes through. The column is then washed with 50 cc. of distilled water. The effluent and the wash water are combined, and evaporated down with HNOa three times, then taken up with 0.01 N HNO3. The final volume is 70 cc., and contains 84% of the phosphorus activity.

Example III A nitric acid solution prepared from irradiated sulfur as in Example I is evaporated down to near dryness, then taken up in a volume of ml. of water, and sufficient La(NOa)s is added to give '75 mg. of La+++ in the solution. Concentrated ammonia is then added to precipitate the lanthanum, and the La(O-'I-I)3 is centrifuged out, dissolved in HCl, and reprecipitated with ammonia. It is then washed in 1 N NH4(JH, and dissolved in concentrated HCl. The acid solution is then diluted to 0.1 N, and the lanthanum removed by passing it through a cation exchange resin column containing Amberlite IR-l (cf. supra) resin as the adsorber. Substantially all of the lanthanum is adsorbed by the resin, and remains in the column, while the acid solution containing phosphorus activity passes through. The column is then washed with 50 cc. of distilled water. The effluent and the wash water are combined, and evaporated down with HNO: three times, then taken up with 0.01 N HNOa. The final volume is 75 cc. and contains 87% of the phosphorus activity.

While my invention has been described with reference to certain particular embodiments and with reference to certain specific examples, it is to be understood that the invention is not limited thereto. Therefore, changes, additions, and/or omissions may be made without departing from the spirit of the invention as defined in the appended claims which are intended to be limited only as required by the prior art.

I claim:

1. A carrier precipitation process for the separation of radioactive phosphorus values from a solution containing said values in the form of phosphate ions in trace concentration therein, which comprises carrier precipitating said phosphate ions from solution upon an insoluble metal hydroxide precipitated in said solution, and separating the resulting carrier precipitate together with radioactive phosphorus values resultingly carrier precipitated from solution thereupon from the remaining supernatant liquid.

2. The process of claim 1 in which the metal hydroxide is precipitated as a gelatinous precipitate.

3. The process of claim 1 in which the metal hydroxide is ferric hydroxide.

4. The process of claim 1 in which the metal hydroxide is aluminum hydroxide.

5. The process of claim 1 in which the metal hydroxide is lanthanum hydroxide.

6. A carrier precipitation process for the recovery of radioactive phosphorus values from a solution containing said values in the form of phosphate ions in trace concentration therein, which comprises carrier precipitating said phosphate ions from solution upon an insoluble metal hydroxide precipitated in said solution, separating the resulting metal hydroxide carrier precipitate together with radioactive phosphorus values resultingly carrier precipitated from solution thereupon from the supernatant solution, dissolving the separated precipitate and its associated radioactive phosphorus values in an aqueous inorganic acid, and eliminating from 6 the resulting solution the cation of the metal hydroxide employed.

7. The process of claim 6 in which the metal cation is eliminated from the final solution by solvent extraction.

8. The process of claim 6 in which the metal cation is eliminated from the final solution by adsorption on a cation exchange adsorbent.

9. A process for the recovery of phosphorus values from a mass of sulfur containing phosphorus, which comprises contacting, by admixing, said mass of sulfur, in molten state, with aqueous nitric acid, thereafter cooling the resulting liquid admixture, thereby causing the bulk of molten sulfur to solidify leaving said phosphorus dissolved in the aqueous nitric acid, and thereupon separating the obtained supernatant, phosphorus-values-containing, aqueous nitric acid solution from the resulting bulk of solidified sulfur.

10. A process for the recovery of radioactive phosphorus values from a mass of neutronirradiated sulfur inherently containing the same, which comprises introducing said mass of sulfur, in molten state, into boiling concentrated nitric acid, thereafter cooling the resulting admixture, thereby causing the bulk of molten sulfur to solidify leaving said phosphorus values dissolved in the nitric acid, and thereupon separating the obtained supernatant, radioactive-phosphorusvalues-containing nitric acid solution from the resulting bulk of solidified sulfur.

11. A process for the recovery of radioactive phosphorus values from a mass of neutronirradiated sulfur inherently containing the same, which comprises contacting, by admixing, said mass of sulfur, in molten state, with aqueous nitric acid, cooling the resulting liquid admixture, thereby causing the bulk of molten sulfur to solidify leaving said phosphorus value dissolved in the aqueous nitric acid, thereupon separating the obtained radioactive-phosphorusvalues-containing aqueous nitric acid solution from the bulk of solidified sulfur, thereafter carrier precipitating said radioactive phosphorus values from solution upon a metal hydroxide precipitate insoluble in said aqueous nitric acid solution, by means of precipitating an insoluble metal hydroxide in the obtained separated solution, and separating the metal hydroxide precipitate together with radioactive phosphorus values resultingly carrier precipitated from solution thereupon from the remaining supernatant solution.

12. A process for the recovery of radioactive phosphorus values from a mass of neutronirradiated sulfur inherently containing the same, which comprises contacting, by admixing, said mass of sulfur, in molten state, with aqueous nitric acid, cooling the resulting liquid admixture, thereby causing the bulk of molten sulfur to solidify leaving said phosphorus values dissolved in the aqueous nitric acid, thereupon separating the obtained radioactive-phosphorusvalues-containing aqueous nitric acid solution from the bulk of solidified sulfur, thereafter carrier precipitating said radioactive phosphorus values from solution upon a metal hydroxide precipitate insoluble in said aqueous nitric acid solution, by means of precipitating an insoluble metal hydroxide in the obtained separated solution, separating the metal hydroxide precipitate together with radioactive phosphorus values resultingly carrier precipitated from solution thereupon, dissolving the separated precipitate and its associated radioactive phosphorus values in an aqueous inorganic acid, and eliminating from the resulting solution the cation of the metal hydroxide employed.

13. The process of claim 12 in which: the metal hydroxide is ferric hydroxide, the aqueous inorganic acid is hydrochloric acid, and the elimination of the cation of the metal hydroxide employed is efiected by extraction, as ferric chloride, into isopropyl ether.

14. The process of claim 12 in which: the metal hydroxide is lanthanum hydroxide, the

aqueous inorganic acid is hydrochloric acid, and

the elimination of the cation of the metal hydroxide employed is effected by adsorption upon a phenol-formaldehyde cation-exchange resin.

' WALDO E. COHN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,053,319 Block et a1 ..1 Sept. 8, 1936 2,206,634

Fermi et a1. July 2, 1940 8 OTHER REFERENCES Zieler: Zeitschrift fiir Anorganische Chemie, volume 162, page 179, Tabelle 8, Vers. 46 (1927).

Mellor: Inorganic and Theoretical Chemistry, volume 10, pages 31, 32 (1930). Published by Longmans, Green and Company, London.

Freundlich: Colloid and Capillary Chemistry, translated from third German edition by H. "Stafford Hatfield. E. P. Dutton and Co., N. Y., 1930, pages 220, 222.

Meyers: Ion Exchange Resins, Industrial and Engineering Chemistry, August 1933, pages 858-, 863.

Britton: Hydrogen Ions, pages 325-7, and 333 (1929). Published by D. Van Nostrand, New York.

Claims (1)

12. A PROCESS FOR THE RECOVERY OF RADIOACTIVE PHOSPHORUS VALUES FROM A MASS OF NEUTRONIRRADIATED SULFUR INHERENTLY CONTAINING THE SAME, WHICH COMPRISES CONTACTING, BY ADMIXING, SAID MASS OF SULFUR, IN MOLTEN STATE, WITH AQUEOUS NITRIC ACID, COOLING THE RESULTING LIQUID ADMIXTURE, THEREBY CAUSING THE BULK OF MOLTEN SULFUR TO SOLIDIFY LEAVING SAID PHOSPHORUS VALUES DISSOLVED IN THE AQUEOUS NITRIC ACID THEREUPON SEPARATING THE OBTAINED RADIOACTIVE-PHOSPHORUSVALUES-CONTAINING AQUEOUS NITRIC ACID SOLUTION FROM THE BULK OF SOLIDIFIED SULFUR, THEREAFTER CARRIER PRECIPITATING SAID RADIOACTIVE PHOSPHORUS VALUES FROM SOLUTION UPON A METAL HYDROXIDE PRECIPITATE INSOLUBLE IN SAID AQUEOUS NITRIC ACID SOLUTION, BY MEANS OF PRECIPITATING AN INSOLUBLE METAL HYDROXIDE IN THE OBTAINED SEPARATED SOLUTION, SEPARATING THE METAL HYDROXIDE PRECIPITATE TOGETHER WITH RADIOACTIVE PHOSPHORUS VALUES RESULTINGLY CARRIER PRECIPITATED FROM SOLITION THEREUPON, DISSOLVING THE SEPARATED PRECIPITATE AND ITS ASSOCIATED RADIOACTIVE PHOSPHORUS VALUES IN AN AQUEOUS INORGANIC ACID, AND ELIMINATING FROM THE RESULTING SOLUTION THE CATION OF THE METAL HYDROXIDE EMPLOYED.