RU2489761C1 - Method of producing sodium-22 from proton-irradiated aluminium target - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing sodium-22 from a proton-irradiated aluminium target involves dissolving an irradiated aluminium target in concentrated hydrochloric acid, precipitating a portion of aluminium ions and heavy metal impurities from the solution of the aluminium target in form of oxide hydrates, sorbing aluminium and sodium-22 ions from the obtained solution on cation-exchange resin Dowex 50w and desorbing sodium-22 from the cation-exchange resin Dowex 50w.

EFFECT: invention simplifies the technique of extracting sodium-22.

4 cl, 1 dwg

Description

The invention relates to radiochemistry and can be used to produce sodium-22, used for the production of gamma and positron radiation sources.

A known method of producing sodium-22 by distillation from a molten proton-irradiated aluminum target and subsequent capture on a cold surface (Griffm H.C., Steiger, etc. "System for separating radioactiv Na from Al". US Patent 4894208).

The disadvantages of this method: complex hardware design and the potential danger of a possible release of radioactive sodium into the surrounding air.

Closest to the technical nature of the claimed method is a method for producing sodium-22 (Taylor W.A .; Heaton R.C. "Production of sodium-22 from proton irradiated alumunwn" US Patent 5487880).

The known method includes dissolving an aluminum target irradiated with protons, precipitating a portion of aluminum ions from an aluminum target solution, sorption of aluminum and sodium-22 ions from the resulting solution on a cation exchange resin, and desorption of sodium-22 from a cation exchange resin.

The disadvantages of this method:

- part of the aluminum ions precipitated from a solution of an aluminum target in the form of aluminum chloride, which requires repeated repetition of this operation;

- the solution obtained after the precipitation of part of the aluminum ions is purified from copper and iron impurities by sorption on anion exchange resin.

The technical result of the invention is to simplify the technology of the allocation of sodium-22.

To achieve a technical result in a method for producing sodium-22 from an aluminum target irradiated with protons, including dissolving an irradiated aluminum target, precipitating a portion of aluminum ions and impurity heavy metals from an aluminum target solution, sorption of sodium-22 and residual aluminum ions from the resulting solution on a cation exchange resin, and desorption of sodium-22 from a cation exchange resin, it is proposed that aluminum ions and heavy metal impurities be precipitated from a solution of an aluminum target in the form of aluminum oxide hydrate and ok heavy metal words.

In particular cases of application of the method it is proposed:

- dissolve the aluminum target in concentrated hydrochloric acid;

- to clear the obtained acid solution of sodium-22 from traces of cations on a cation exchange resin;

- Use Dowex 50w as a cation exchange resin.

The invention is illustrated in FIG. 1 by a flowchart of a process for producing a sodium-22 solution.

The following notation is used in FIG. 1: 1 — dissolution of an aluminum target irradiated with protons, 2 — evaporation of the solution to a minimum volume, 3 — precipitation of a part of aluminum ions and impurity heavy metals in the form of oxide hydrates, 4 — evaporation of a solution of sodium-22 and remaining aluminum with simultaneous decomposition of excess ammonium carbonate, 5 - adjustment of the acidity of the solution, 6 - purification of sodium-22 ions from aluminum on a cation exchange resin (operations 5 and 6 are repeated twice), 7 - purification of the obtained sodium-22 acid solution from traces of cat ion sorption on a cation exchange resin.

The method is used as follows.

Dissolve the proton-irradiated aluminum target in a 3 ÷ 12 M hydrochloric acid solution to form a solution containing aluminum and sodium ions.

An aluminum target solution containing aluminum, sodium and impurity heavy metal ions is evaporated to a minimum volume.

Part of the aluminum and impurity heavy metals are precipitated in the form of oxide hydrates by adding a 3–4 fold excess of ammonium carbonate to the solution. The precipitate is filtered off, washed with 1 ÷ 2 M ammonium carbonate solution, the washing solution is combined with the filtrate.

Evaporate the resulting solution containing sodium ions, the remaining aluminum ions and excess ammonium carbonate to dryness, while ammonium carbonate decomposes and evaporates in the form of gases.

The dry residue is dissolved in 0.01 ÷ 0.06 M hydrochloric acid. The resulting solution is passed through a cation exchange resin column, while aluminum and sodium ions are adsorbed on the column. The cation exchange column is washed with distilled water until sodium ions appear at the outlet of the column.

Sodium is desorbed from a cation exchange column with a 0.1 ÷ 0.5 M hydrochloric acid solution. The resulting desorbate is evaporated to dryness.

The dry residue is dissolved in 0.01 ÷ 0.06 M hydrochloric acid. Pass the resulting solution through a second column with a cation exchange resin. Wash the column with distilled water until sodium ions appear at the outlet of the column.

Sodium is stripped from the column with 0.1 ÷ 0.5 M hydrochloric acid solution. The desorbate is evaporated to dryness.

The dry residue is dissolved in the required volume of hydrochloric or nitric acid of the required concentration.

An example of a specific application of the method of producing sodium-22.

The aluminum target irradiated with protons is dissolved in a 12 M hydrochloric acid solution to form a solution containing aluminum and sodium ions.

Evaporate the resulting solution containing aluminum ions, sodium-22 and impurity heavy metals to a minimum volume.

Part of the aluminum ions and impurity heavy metals are precipitated in the form of oxide hydrates by adding a 3.5-fold excess of ammonium carbonate to the solution. The precipitate of alumina hydrate is filtered off. The precipitate of alumina hydrate is washed with a 1.5 M solution of ammonium carbonate, and the wash solution is combined with the filtrate.

Evaporate the resulting solution containing sodium ions, the remaining aluminum ions and excess ammonium carbonate to dryness, while the ammonium carbonate decomposes and evaporates in the form of gases.

Dissolve the dry residue in a 0.01 M hydrochloric acid solution. Pass the resulting solution through a Dowex 50w cation exchange resin column.

Wash the column with distilled water until sodium ions appear at the outlet of the column. Sodium is stripped from the cation exchange column with a 0.2 M hydrochloric acid solution. The resulting desorbate is evaporated to dryness.

Dissolve the dry residue in a 0.01 M hydrochloric acid solution. Pass the resulting solution through a second column with a Dowex 50w cation exchange resin. Wash the column with distilled water until sodium ions appear at the outlet of the column. Sodium-22 is stripped from the cation exchange column with a 0.2 M hydrochloric acid solution. The desorbate is evaporated to dryness.

The dry residue is dissolved in the required volume of hydrochloric or nitric acid of the required concentration. The resulting solution is a finished solution of sodium-22.

Claims (4)

1. A method of producing sodium-22 from a proton-irradiated aluminum target, comprising dissolving an irradiated aluminum target, precipitating a portion of aluminum ions and impurity heavy metals from an aluminum target solution, sorption of sodium-22 and residual aluminum ions from the resulting solution on a cation exchange resin, and sodium desorption 22 cation exchange resin, characterized in that the ions of aluminum and impurity heavy metals are precipitated from a solution of an aluminum target in the form of alumina hydrate and hydrates of heavy metal oxides. 2. The method according to claim 1, characterized in that the aluminum target is dissolved in concentrated hydrochloric acid. 3. The method according to claim 1, characterized in that the obtained acid solution of sodium-22 is purified from traces of cations on a cation exchange resin. 4. The method according to claim 1, characterized in that Dowex 50w is used as the cation exchange resin.