Method of removing strontium cations from a water stream using an amorphous titanium silicate

Patent metadata

Field	Value
Publication number	US-9744518-B2
Application number	US-201414148929-A
Country	US
Kind code	B2
Filing date	Jan 7, 2014
Priority date	Jan 9, 2013
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

This invention is directed to amorphous and crystalline titanosilicate materials that have an unexpected selectivity for cesium and strontium, especially in the presence of high levels of competing ions. The titanosilicates of this invention show very high, unexpected selectivity in the presence of such competing cations such as sodium, calcium, magnesium and potassium, such as present in seawater.

First claim

The invention claimed is:

1. A method comprising:
contacting a water stream with an amorphous titanium silicate, the water stream containing strontium cations and at least one of sodium cations, potassium cations, calcium cations, or magnesium cations, the amorphous titanium silicate being prepared by contacting a solution of soluble titanium salt with a sodium silicate solution and alkali with stirring, the amorphous titanium silicate being precipitated as a gel and formed into powder or granules without crystalline character prior to the contacting; and
selectively removing a portion of the strontium cations from the water stream by ion exchanging sodium ions on the amorphous titanium silicate for the strontium cations in the water stream in response to the contacting of the water stream with the amorphous titanium silicate.

2. The method of claim 1 , wherein the titanium silicate has a silicon to titanium (Si:Ti) ratio of from about 2:1 to about 0.5:1.

3. The method of claim 2 , wherein the Si:Ti ratio is from about 1.5:1 to about 0.9:1.

4. The method of claim 1 , wherein the amorphous titanium silicate is present as binder-free granules.

5. The method of claim 1 , wherein said water stream comprises seawater.

6. The method of claim 1 , wherein said water stream comprises surface or ground water.

7. The method of claim 6 , wherein said water
stream is purified to produce potable water, or for remediation of water streams which have been contaminated with the strontium cations.

8. The method of claim 1 , wherein said water stream is from nuclear fuel pool water, or from a seawater flooded nuclear power plant for generating electricity.

9. The method of claim 1 , wherein the water stream contains at least 10 times the amount of the at least one of the sodium cations, the potassium cations, the calcium cations, or the magnesium cations relative to the strontium cations on an equivalent mass per unit volume basis.

10. The method of claim 9 , wherein said water stream comprises seawater.

11. The method of claim 1 , wherein the water stream contains at least 100 times the amount of the at least one of the sodium cations, the potassium cations, the calcium cations, or the magnesium cations relative to the strontium cations on an equivalent mass per unit volume basis.

12. The method of claim 1 , wherein the water stream contains at least 1,000 times the amount of the at least one of the sodium cations, the potassium cations, the calcium cations, or the magnesium cations relative to the strontium cations on an equivalent mass per unit volume basis.

13. The method of claim 1 , wherein the sodium silicate solution is formed by dissolving sodium metasilicate pentahydrate (Na 2 SiO 3 * 500 5H 2 O) in sodium hydroxide (NaOH).

14. The method of claim 1 , wherein the solution of the soluble titanium salt is formed by adding titanium tetrachloride (TiCI 4 ) to deionized water.

15. The method of claim 1 , wherein the powder or the granules of the amorphous titanium silicate has a particle-size distribution of about 20 to 60 mesh.

16. The method of claim 1 , wherein said water stream includes a concentration of sodium cations of about 3181 ppm, a concentration of magnesium cations of about 387 ppm, a concentration of calcium cations of about 108 ppm, a concentration of potassium cations of about 118 ppm, and a concentration of strontium cations of about 4.8 ppm.

17. The method of claim 16 , wherein said step of contacting includes contacting about 1 part by weight of the amorphous titanium silicate to about 10 parts by weight of the water stream, and wherein the step of removing reduces the concentration of strontium ions from about 4.8 ppm to about 0.012 ppm.

18. The method of claim 16 , wherein said step of contacting includes contacting about 1 part by weight of the amorphous titanium silicate to about 100 parts by weight of the water stream, and wherein the step of removing reduces the concentration of strontium ions from about 4.8 ppm to about 0.335 ppm.

19. The method of claim 16 , wherein said step of contacting includes contacting about 1 part by weight of the amorphous titanium silicate to about 1000 parts by weight of the water stream, and wherein the step of removing reduces the concentration of strontium ions from about 4.8 ppm to about 3 ppm.

Assignees

• Basf Corp

Inventors

• Maglio Alfonse
• Durocher David

Classifications

• B01J20/28047

  Gels · CPC title

• C02F2101/006

  Radioactive compounds · CPC title

• B01J20/28061

  being in the range 100-500 m2/g · CPC title

• B01J39/14

  Base exchange silicates, e.g. zeolites · CPC title

• G21F9/12

  by absorption; by adsorption; by ion-exchange · CPC title