# US 5,346,678 A · Production of high specific activity silicon-32 > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,346,678 A - Document ID: US5346678A - Status: Granted - Kind: A - Application number: 07/950,552 - Filed: 1992-09-25 - Granted: 1994-09-13 - Earliest claimed: 1992-09-25 - Assignees: The United States of America as represented by the United States Department of Energy - Inventors: Dennis R. Phillips; Mark A. Brzezinski - Web page: https://patentgrep.com/patent/US5346678A ## CPC - G21G 1/10: by bombardment with electrically charged particles (irradiation devices G21K5/00) - C01B 33/02: Silicon (forming single crystals or homogeneous polycrystalline material with defined structure C30B) - G21G: CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES (applications of radiation in general G21H5/00; handling particles, e.g. neutrons, or electromagnetic radiation not otherwise provided for G21K) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} ## Abstract A process for preparation of silicon-32 is provide and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided. ## Claims ### Claim 1 A process for preparation of a high purity, high specific activity silicon-32 solution comprising: contacting an irradiated potassium chloride target containing spallation products with a sufficient amount of water, hydrochloric acid or potassium hydroxide to form a first solution; filtering the first solution; adjusting pH of the first solution to within a range of from about 5.5 to about 7.5; admixing a sufficient amount of a molybdate-reagent and a dilute acid with the first solution whereby the pH of the first solution is adjusted to about 1.5 and a silicon-molybdate complex is formed; contacting the first solution including the silicon-molybdate complex with a dextran-based material whereby the silicon-molybdate complex is adsorbed from the first solution onto the dextran-based material; washing the dextran-based material with a sufficient amount of a dilute acid containing a soluble metal halide to remove substantially all residual contaminants; separating the silicon-molybdate complex from the dextran-based material into a second solution; adding amounts of hydrochloric acid and hydrogen peroxide to the second solution sufficient to maintain separation of the silicon and molybdate ions and to yield an oxidation state of the molybdate adapted for subsequent separation onto an anionic exchange material; and, contacting the second solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in the second solution. ### Claim 2 (depends on 1) The process of claim 1 further comprising adding sufficient alkali metal hydroxide to adjust the pH of the second solution to about 12 to 13. ### Claim 3 (depends on 1) The process of claim 1 wherein the molybdate-reagent is ammonium molybdate. ### Claim 4 (depends on 1) The process of claim 1 wherein the molybdate-reagent is substantially free of silicon. ### Claim 5 (depends on 1) The process of claim 1 wherein the metal halide is sodium chloride. ### Claim 6 (depends on 1) The process of claim 1 wherein the process is conducted in apparatus essentially free of silicon. ### Claim 7 (depends on 1) The process of claim 1 wherein the process is conducted in apparatus comprised of plastic. ### Claim 8 A process for preparation of a high purity, high specific activity silicon-32 solution comprising: contacting an irradiated potassium chloride target containing spallation products with a sufficient amount of water, hydrochloric acid or potassium hydroxide to form a first solution; filtering the first solution; adjusting pH of the first solution to within a range of from about 5.5 to about 7.5; admixing a sufficient amount of a molybdate-reagent and a dilute acid with the first solution whereby the pH of the first solution is adjusted to about 1.5 and a silicon-molybdate complex is formed; contacting the first solution including the silicon-molybdate complex with a dextran-based material whereby the silicon-molybdate complex is adsorbed from the first solution onto the dextran-based material; washing the dextran-based material with a sufficient amount of a dilute acid containing a soluble metal halide to remove substantially all residual contaminants except sodium-22; eluting the dextran-based material with a dilute base whereby the silicon-molybdate complex and sodium-22 are separated from the dextran-based material in a second solution; admixing a solution including a sufficient amount of a molybdate-reagent, a dilute acid, and a soluble metal halide, with the second solution whereby the pH of the second solution is adjusted to about 1.5 and the metal halide concentration is at least about 25 g/l and a silicon-molybdate complex is formed; contacting the second solution with a second dextran-based material whereby the silicon-molybdate complex is adsorbed from the second solution onto the second dextran-based material; washing the second dextran-based material with an amount of a dilute acid solution containing at least about 25 g/l of a soluble metal halide, said amount of solution sufficient to remove substantially all of the sodium-22 from the second dextran-based material; separating the silicon-molybdate complex from the dextran-based material into a third solution; adding amounts of hydrochloric acid and hydrogen peroxide to the third solution sufficient to maintain separation of the silicon and molybdate ions and to yield an oxidation state of the molybdate adapted for subsequent separation onto an anionic exchange material; and, contacting the third solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in the third solution. ### Claim 9 (depends on 8) The process of claim 8 further comprising adding sufficient alkali metal hydroxide to adjust the pH of the third solution to about 12 to 13. ### Claim 10 (depends on 8) The process of claim 8 wherein the molybdate-reagent is ammonium molybdate. ### Claim 11 (depends on 8) The process of claim 8 wherein the molybdate-reagent is substantially free of silicon. ### Claim 12 (depends on 8) The process of claim 8 wherein the metal halide is sodium chloride. ### Claim 13 (depends on 8) The process of claim 8 wherein the process is conducted in apparatus essentially free of silicon. ### Claim 14 (depends on 8) The process of claim 8 wherein the process is conducted in apparatus comprised of plastic.