US3616276A - Process for changing the valence of a metal of variable valence in an organic solution - Google Patents

Process for changing the valence of a metal of variable valence in an organic solution Download PDF

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US3616276A
US3616276A US815714A US3616276DA US3616276A US 3616276 A US3616276 A US 3616276A US 815714 A US815714 A US 815714A US 3616276D A US3616276D A US 3616276DA US 3616276 A US3616276 A US 3616276A
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aqueous solution
organic solution
metal
solution
cell
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US815714A
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Alfred Schneider
Arnold Leslie Ayers
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Honeywell International Inc
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Allied Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G56/00—Compounds of transuranic elements
    • C01G56/007—Compounds of transuranic elements
    • C01G56/008—Compounds of neptunium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G56/00—Compounds of transuranic elements
    • C01G56/001—Preparation involving a liquid-liquid extraction, an adsorption or an ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G56/00—Compounds of transuranic elements
    • C01G56/004—Compounds of plutonium
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals

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  • This invention relates to a process for changing the valence of a metal in organic solution. More particularly, the invention relates to a process for changing the valence of a metal in organic solution by electrochemical means.
  • uranium can be precipitated from organic solution with HF. Since the uranium is generally in a higher valence state, it must be reduced to its tetravalent state prior to precipitation.
  • mixtures of trivalent plutonium and hexavalent uranium in organic solution can be separated from each other by selective extraction with an immiscible aqueous solution whereby the uranium remains in the organic phase and the plutonium transfers to the aqueous phase. Since the plutonium is generally in its tetravalent state, it must be reduced to the trivalent state prior to separation.
  • US. Pat. No. 3,361 ,65l discloses that tetravalent plutonium in a dilute nitric acid solution with hexavalent uranium can be reduced to its trivalent state electrolytically. This process has the disadvantage that the metals must be in aqueous solution. If the metals are in organic solution, they must, therefore, be first extracted with the nitric acid solution.
  • the valence of one or more metals of variable valence in an organic solution can be changed electrochemically by forming a dispersion by agitating said organic solution and an immiscible aqueous solution and passing an electric current through the dispersion in the cathode zone of an electrolytic cell (if a lower valence state is desired) or in the anode zone (if a higher valence state is desired), the anode and cathode zones being separated by a porous membrane, to effect a change in valence state of one or more of the metals.
  • FIGURE is a schematic sectional view of an electrolytical cell separated into two zones by a porous membrane.
  • the present process is applicable to change the valence of a single metal in an organic solution so that it can be further processed. It is also applicable to change the valence of a metal in organic solution and effect a transfer of the metal to an immiscible aqueous solution in a single step.
  • the distribution coefficient of the metal is affected by a change in valence and the aqueous solution is a preferential solvent for the metal in its reduced or oxidized state, the immiscible solutions are separated and the aqueous solution will be enriched in the metal in its new valence state whereas the organic solution will be depleted in that metal.
  • organic solutions containing two or more metals of variable valence one of which has a distribution coefficient affected by a change in the valence, can be treated electrochemically and the metals separated from each other in a single step. After electrochemical treatment, one of the metals will have transferred to the aqueous solution and the other metal(s) will remain in the organic solution.
  • the process of the invention can be used to reduce hflib avalent uranium to tetravalent uranium in an organic solution by forming a dispersion of the organic solution by agitating with a dilute nitric acid solution in the cathode zone of an electrolytic cell separated into an anode zone and a cathode zone by a porous membrane and passing a current through the cell. Tetravalent uranium in the organic solution will be obtained.
  • the process can also be used to reduce tetravlaent plutonium to trivalent plutonium in an organic solution and extract the trivalent plutonium from the organic solution by forming a dispersion by agitating the organic solution and a dilute nitric acid solution in the cathode zone of an electrolytic cell and passing a current through the cell.
  • the tetravalent plutonium will be reduced to trivalent plutonium which is preferentially soluble in and hence extracted by the dilute nitric acid.
  • the organic solution will be depleted in plutonium whereas the aqueous solution will be enriched in plutonium in its trivalent state.
  • the process is also suitable for the selective reduction of a tetravalent plutonium to trivalent plutonium in an organic solution containing tetravalent plutonium and hexavalent uranium obtained during the processing of nuclear fuels.
  • lPlutonium can be separated from the uranium in such an organic solution by forming a dispersion by agitating the organic solution and a dilute nitric acid solution in the cathode zone of an electrolytic cell and passing a current through the cell.
  • the tetravalent plutonium is reduced to trivalent plutonium, which is preferentially soluble in and transfers to the dilute nitric acid solution.
  • the plutonium When the organic and aqueous phases are separated, most of the plutonium will be found in the aqueous phase and most of the uranium will remain in the organic phase. Thus, the plutonium can be separated form the uranium rapidly, in a single step without the addition of any reducing agents.
  • the process can also be employed in purifying metal solutions.
  • Organic solutions containing uranium, plutonium, or both, and metallic impurities in trace quantities, such as ruthenium, zirconium, niobium and the like, can be treated by forming a dispersion with a dilute nitric acid solution in the anode zone of the cell.
  • the trace impurities will be found in the aqueous phase.
  • the present process can of course also be applied to oxidation reactions by forming a dispersion by agitating an organic solution with an immiscible aqueous solution in the anode compartment of the electrolytic cell and passing a current through the cell.
  • an organic solution containing tetravalent plutonium and tetravalent neptunium can be treated to provide an organic solution containing most of the plutonium and an aqueous solution containing most of the neptunium in its pentavalent state.
  • Solutions containing from about 5 to percent by weight of an alkyl phosphate, optionally in an organic diluent. are
  • the alkyl phosphates can be mono-, di-, or triesters of phosphoric acid derived from alkanols containing one to about eight carbon atoms such as butanol, hexanol, octanol and the like.
  • Tributyl phosphate in an amount of from about 20 to 40 percent by weight in a hydrocarbon diluent is generally employed as solvent for metals found in nuclear fuels, i.e., uranium, plutonium and neptunium, due to its high extraction selectivity.
  • the diluents can be hydrocarbons such as dodecane, kerosene, gasoline and the like.
  • Other organic solvents including ketones, such as hexone or amines such as dioctylamine, the latter in a suitable diluent, can also be employed.
  • the aqueous solution must be immiscible with the organic solution and must be an electrolyte. Suitable aqueous solutions are dilute mineral acid or salt solutions, such as nitric acid, sodium nitrate and the like.
  • the aqueous solution can also contain a stabilizer, such as hydrazine, to prevent reoxidation of the metals.
  • the hydrazine can be present in the aqueous solution in an amount of from 0.01 to about 0.5 M.
  • the electrolytic cell employed in carrying out the present invention is conventional and its exact size, shape, and the like can be varied and does not form part of the invention.
  • the cell as further described below is arranged for a reduction operation.
  • the cell 1 is divided into an anode zone 2 and acathode zone 3 by a porous membrane 4.
  • the membrane 4 can be an inorganic porous membrane such as alumina, or an organic ion exchange membrane. [on exchange membranes are generally available as an anionic or cationic exchange resin in a film forming matrix such as polyethylene or a vinyl resin.
  • the anode zone 2 contains an anode 5 and the cathode zone 3 contains a cathode 6.
  • the electrodes can be of conventional materials such as platinum, tantalum, niobium, carbon and the like. Platinum is preferred for the electrodes.
  • the cell 1 is also fitted with inlet ports, 7, 8 and 9 and exit ports 10 and 111.
  • the cathode zone 3 is also fitted with a stirrer 12 which is adequate to effect and maintain a dispersion ofa mixture of organic and aqueous solutions in the cathode zone 3.
  • the cell 1 can also be fitted with means of cooling and/or heating, externally or internally (not shown).
  • the anode zone 2 contains an aqueous solution of an electrolyte and the cathode zone is partially filled with the same or a different electrolyte.
  • the ratio by volume of organic to electrolyte solutions through which a current can be effectively passed varies somewhat depending on the degree of dispersion of the immiscible phases.
  • the electrolyte must be maintained as the continuous phase during the process. It will be understood that when a reduction is to be carried out, the roles of the anode and the cathode zones are reversed.
  • the aqueous solution can be recycled to the cell and contacted with a fresh batch of the organic solution, either in a batch or semicontinuous manner, to increase the concentration of the metal in the aqueous phase.
  • an internal reduction oxidation (redox) agent can be added to the system.
  • redox agent is reduced or oxidized by the passage of a current through the cell.
  • the redox agent is reduced, in turn reduces the metal whose valence is to be reduced, and is itself oxidized back to its original valence state.
  • concentration of this agent will remain substantially constant.
  • the addition of an internal redox agent is particularly effective when added to dilute solutions of tetravalent plutonium.
  • uranyl nitrate [UO (NO) is generally added to the organic solution as the redox agent.
  • UO uranyl nitrate
  • the hexavalent uranium is reduced to tetravalent uranium, which reduces the tetravalent plutonium, and is then reoxidized to hexavalent uranium according to the equation:
  • EXAMPLE 1 A measured volume of 0.36 M. uranyl nitrate in an organic solution of 30 volume percent of tributyl phosphate in kerosene also containing 0.3 M nitric acid is charged to the cathode zone of an electrolytic cell containing an equal volume of an aqueous solution of 2 M nitric acid and 0.5 M of hydrazine.
  • the anode zone is filled with an aqueous solution of 2 M nitric acid.
  • the anode zone is fitted with a platinum electrode, sealed into one end.
  • the anode zone and the cathode zone are divided by a permeable cation exchange membrane.
  • the cathode zone is fitted with a platinum electrode and is also provided with a stirrer and an internal cooling coil.
  • the stirrer is turned on to form a dispersion in the cathode zone, and a current density of 0.1 a./sq.cm. at a potential of 7.3 volts is applied to the cell.
  • the hexavalent uranium is reduced to tetravalent uranium. After 2 hours 65 percent of the uranium is reduced.
  • the proportion of tetravalent uranium in the organic phase increases.
  • EXAMPLE 2 An organic solution containing 82 grams per liter of uranyl nitrate and 1 gram per liter of tetravalent plutonium nitrate in 30 volume percent of tributyl phosphate and kerosene is charged to the cathode zone of the electrolytic cell of example 1, containing an equal volume of an aqueous solution of 2.5 M nitric acid and 0.1 M of hydrazine. A dispersion is formed, and
  • EXAMPLE 4 An organic solution of 30 volume percent of tributyl phosphate in kerosene containing 6 mg./ml. of tetravalent neptunium is charged to the anode zone of the electrolytic cell of example 1 containing an equal volume of an aqueous solution of l M nitric acid. A dispersion is formed and current density of 0.1 a./sq.cm. at a potential of 11 volts is applied. After 3 hours nearly all of the neptunium is present in the pentavalent state in the aqueous phase.
  • EXAMPLE 5 An organic solution containing 6 mg./ml. of tetravalent plutonium and 6 mgJml. of tetravalent neptunium in 30 volume percent of tributyl phosphate in kerosene is charged to the anode zone of the electrolytic cell of example 1 containing an equal volume of an aqueous solution of 2 M nitric acid. The current density applied is 0.1 a./sq.cm. at a potential of 11 volts. After 3 hours almost all of the neptunium is oxidized to the pentavalent state and transfers to the aqueous phase, whereas the concentration of plutonium in the organic phase remains substantially the same.
  • a process for changing the valence of a metal of variable valence state in an organic solution which comprises forming a dispersion by agitating the organic solution with an immiscible aqueous solution, as electrolyte, and, while maintaining the electrolyte as the continuous phase, passing an electric current through the dispersion in the cathode zone of an electrolytic cell (if a lower valence state ofthe metal is desired) or in the anode zone of the cell (if a higher valence state of the metal is desired), the cathode and anode zones of the cell being separated by a porous membrane, whereby the valence state of the metal becomes lower or higher.
  • organic solution contains uranium and from about 5 to 100 percent by weight of an alkyl phosphate optionally containing a hydrocarbon diluent.
  • a process according to claim 2 wherein the aqueous solution is a dilute nitric acid solution.
  • a process for extracting a metal of variable valence state from an organic solution containing the metal which comprises forming a dispersion by agitating the organic solution with, as electrolyte, and immiscible aqueous solution which is a preferential solvent for the metal in a lower or higher valence state and, while maintaining the electrolyte as the continuous phase, passing an electric current through the dispersion in the cathode zone of an electrolytic cell (if a lower valence state of the metal is desired or in the anode zone of the cell (if a higher valence state of the metal is desired), the cathode and anode zones of the cell being separated by a porous membrane, whereby the valence state of the metal becomes lower or higher and the metal transfers from the organic solution to the aqueous solution, and seperating the organic solution from the immiscible aqueous solution.
  • a process for separating metals of variable valence states in an organic solution which comprises forming a dispersion by agitating the organic solution with, as electrolyte, an immiscible aqueous solution which is a preferential solvent for one of the metals in a lower or higher valence state and, while maintaining the electrolyte as the continuous phase, passing an electric current through the dispersion in the cathode zone of an electrolytic cell (if a lower valence state of said metal is desired) or in the anode zone of the cell (if a higher valence state of said metal is desired), the cathode and anode zones of the cell being separated by a porous membrane, whereby the valence state of said metal becomes higher or lower and said metal transfers from the organic solution to the aqueous solution, and separating the organic solution from the immiscible aqueous solution.
  • the organic solution contains hexavalent uranium and tetravalent plutonium and from about 20 to about 40 percent by weight of an alkyl phosphate in a hydrocarbon diluent
  • the immiscible aqueous solution is a dilute nitric acid solution
  • the dispersion is charged to the cathode zone of the cell, whereby the uranium remains in the organic solution and the plutonium is reduced to trivalent plutonium which transfers :to the aqueous solution.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Metallurgy (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)
  • Extraction Or Liquid Replacement (AREA)
US815714A 1969-04-14 1969-04-14 Process for changing the valence of a metal of variable valence in an organic solution Expired - Lifetime US3616276A (en)

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JP (1) JPS4915549B1 (https=)
BE (1) BE748151A (https=)
CA (1) CA974476A (https=)
DE (2) DE2016506B2 (https=)
FR (1) FR2041169B1 (https=)
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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3755114A (en) * 1971-04-14 1973-08-28 Hooker Chemical Corp Decreasing the metallic content of liquids by an electrochemical technique
US3770612A (en) * 1970-08-24 1973-11-06 Allied Chem Apparatus for electrolytic oxidation or reduction, concentration, and separation of elements in solution
US3957615A (en) * 1972-12-28 1976-05-18 Gesellschaft Fur Kernforschung M.B.H. Apparatus for conducting electrolytic reactions
US4129481A (en) * 1976-02-13 1978-12-12 Commissariat A L'energie Atomique Uranium isotopic enrichment
US4243494A (en) * 1979-04-19 1981-01-06 Kerr-Mcgee Corporation Process for oxidizing a metal of variable valence by controlled potential electrolysis
US4279705A (en) * 1980-02-19 1981-07-21 Kerr-Mcgee Corporation Process for oxidizing a metal of variable valence by constant current electrolysis
US4341602A (en) * 1978-08-17 1982-07-27 Rhone-Poulenc Industries Extraction of uranium using electrolytic oxidization and reduction in bath compartments of a single cell
US4371505A (en) * 1979-02-28 1983-02-01 Rhone-Poulenc Industries Process for the recovery of uranium contained in an impure phosphoric acid
US4741810A (en) * 1983-12-14 1988-05-03 Kernforschugszentrum Karlsruhe Gmbh Process for reductive plutonium stripping from an organic reprocessing solution into an aqueous, nitric acid solution by use of an electrolytic current
US5069827A (en) * 1987-10-13 1991-12-03 Commissariat A L'energie Atomique Process for reducing and dissolving puo2
US5071516A (en) * 1988-05-13 1991-12-10 Nagakazu Furuya Process for converting ionic valence number
CN113293390A (zh) * 2021-04-26 2021-08-24 西北工业大学 一种在水溶液中电化学还原制备五价铀的方法、装置及其应用

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS517736U (https=) * 1974-07-04 1976-01-20
JPS5367939U (https=) * 1976-11-10 1978-06-07
DE2929122A1 (de) * 1979-07-18 1981-02-05 Alkem Gmbh Verfahren zur elektrochemischen einstellung der pu (vi)-oxidationsstufe
JP7362439B2 (ja) * 2019-11-14 2023-10-17 株式会社東芝 電解抽出装置および電解抽出方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2733200A (en) * 1956-01-31 Kunin
FR90703E (fr) * 1964-06-19 1968-02-02 Commissariat Energie Atomique Procédé de purification et de concentration simultanées du plutonium et plutonium obtenu selon ce procédé

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3770612A (en) * 1970-08-24 1973-11-06 Allied Chem Apparatus for electrolytic oxidation or reduction, concentration, and separation of elements in solution
US3755114A (en) * 1971-04-14 1973-08-28 Hooker Chemical Corp Decreasing the metallic content of liquids by an electrochemical technique
US3957615A (en) * 1972-12-28 1976-05-18 Gesellschaft Fur Kernforschung M.B.H. Apparatus for conducting electrolytic reactions
US4129481A (en) * 1976-02-13 1978-12-12 Commissariat A L'energie Atomique Uranium isotopic enrichment
US4341602A (en) * 1978-08-17 1982-07-27 Rhone-Poulenc Industries Extraction of uranium using electrolytic oxidization and reduction in bath compartments of a single cell
US4371505A (en) * 1979-02-28 1983-02-01 Rhone-Poulenc Industries Process for the recovery of uranium contained in an impure phosphoric acid
US4243494A (en) * 1979-04-19 1981-01-06 Kerr-Mcgee Corporation Process for oxidizing a metal of variable valence by controlled potential electrolysis
US4279705A (en) * 1980-02-19 1981-07-21 Kerr-Mcgee Corporation Process for oxidizing a metal of variable valence by constant current electrolysis
US4741810A (en) * 1983-12-14 1988-05-03 Kernforschugszentrum Karlsruhe Gmbh Process for reductive plutonium stripping from an organic reprocessing solution into an aqueous, nitric acid solution by use of an electrolytic current
US5069827A (en) * 1987-10-13 1991-12-03 Commissariat A L'energie Atomique Process for reducing and dissolving puo2
US5071516A (en) * 1988-05-13 1991-12-10 Nagakazu Furuya Process for converting ionic valence number
CN113293390A (zh) * 2021-04-26 2021-08-24 西北工业大学 一种在水溶液中电化学还原制备五价铀的方法、装置及其应用

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NL7003805A (https=) 1970-10-16
DE2016506B2 (de) 1980-06-04
DE2016506A1 (de) 1972-01-13
JPS4915549B1 (https=) 1974-04-16
BE748151A (fr) 1970-08-31
FR2041169B1 (https=) 1973-07-13
CA974476A (en) 1975-09-16
FR2041169A1 (https=) 1971-01-29
GB1301376A (https=) 1972-12-29

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