Method for extracting metals from aqueous waste streams for long term storage
AssigneeThe United States of America as represented by the United States Department of Energy
InventorDavid J. Chaiko
Life of this patent
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Abstract
A liquid--liquid extraction method for removing metals and hydrous metal colloids from waste streams is provided wherein said waste streams are contacted with a solvent system containing a water-in-oil microemulsion wherein the inverted micelles contain the extracted metal. A silicon alkoxide, either alone or in combination with other metal alkoxide compounds is added to the water-in-oil microemulsion, thereby allowing encapsulation of the extracted metal within a silicon oxide network. Lastly, the now-encapsulated metal is precipitated from the water-in-oil microemulsion phase to yield aggregates of metal-silicate particles having average individual particle sizes of approximately 40 nanometers.
Claims20
A method for extracting a metal material from a waste stream comprising:
- a.) mixing the waste stream with an organic fluid consisting of a metal extractant, a surfactant and an organic diluent in predetermined proportions so as to form an organic phase and an inorganic phase;
- b.) allowing a microemulsion containing inverted micelles to form in the organic phase;
- c.) solubilizing the metal material within the inverted micelles;
- d.) mixing a hydrolyzable alkoxy compound containing silicon with the solubilized metal to form metal-silicate particles;
- e.) adding a sufficient amount of an alkaline material so as to precipitate the metal silicate particles from the organic phase;
- f.) drying the precipitate at a predetermined temperature and for a predetermined time;
- and
- g.) sintering the precipitate at a predetermined temperature so as to produce a monolithic structure.
A method for extracting radioactive metals from an aqueous solution comprising:
- a.) mixing the waste stream with dodecane and octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide and sodium bis(2-ethylhexyl) sulfosuccinate so as to form an organic phase and an inorganic phase;
- b.) allowing a microemulsion containing inverted micelles to form in the organic phase;
- c.) solubilizing the radioactive metals within the inverted micelles;
- d.) mixing a silicon alkoxide with the solubilized radioactive metals to form metal silicate particles;
- e.) adding a sufficient amount of NH.sub.4 OH so as to precipitate the radioactive, metal silicate particles from the organic phase;
- f.) drying the precipitate at a predetermined temperature;
- and
- g.) sintering the precipitate at a predetermined temperature so as to produce a monolithic structure.
A method for extracting polymeric Plutonium (IV) from an aqueous solution comprising:
- a.) mixing the aqueous solution with dodecane and a 2:1 molar ratio mixture of octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide and sodium bis(2-ethylhexyl) sulfosuccinate so as to form an organic phase and an inorganic phase;
- b.) allowing a microemulsion containing inverted micelles to form in the organic phase;
- c.) solubilizing the polymeric Plutonium (IV) within the inverted micelles;
- d.) mixing hydrolyzed tetraethoxysilane with the solubilized metal to form metal silicate particles having an average particle diameter of approximately 40 nm;
- e.) adding a sufficient amount of NH.sub.4 OH so as to precipitate the Plutonium (IV) silicate particles from the organic phase;
- f.) drying the precipitate at approximately 100.degree. C.;
- and
- g.) sintering the precipitate at between 400.degree. C. and 900.degree. C.
Dependencies are inferred from the claim text.