Method for removing heavy metals and radionuclides from an aqueous solution

Abstract

A method for removing heavy metals or radionuclides from an aqueous solution comprising contacting the aqueous solution with an ion exchange material selected from a solid ion exchange material, a liquid ion exchange material, or mixtures thereof, wherein the ion exchange material is prepared by the process comprising: contacting clinoptilolite with an alkaline solution at a temperature of about 85° C. to about 300° C. and for a sufficient time to form a treated slurry comprising a solid fraction and a liquid fraction, and optionally separating the solid fraction from the treated slurry and washing the solid fraction to produce the solid ion exchange material; and optionally recovering the liquid fraction of the treated slurry to produce the liquid ion exchange material. A process for producing the above ion exchange materials useful for removing heavy metals or radionuclides from an aqueous solution, and the solid and liquid ion exchange materials produced by the process.

1 . A method for removing heavy metals or radionuclides from an aqueous solution comprising contacting said aqueous solution with an ion exchange material selected from a solid ion exchange material, a liquid ion exchange material, or mixtures thereof, wherein said ion exchange material is prepared by the process comprising: 
 (a) contacting clinoptilolite with an alkaline solution at a temperature of about 85° C. to about 300° C. and for a sufficient time to form a treated slurry comprising a solid fraction and a liquid fraction, and optionally    (b) separating the solid fraction from said treated slurry and washing the solid fraction to produce said solid ion exchange material; and    (c) recovering the liquid fraction of said treated slurry from step (b) to produce said liquid ion exchange material;    wherein when a solid ion exchange material is used, said solid ion exchange material is the solid ion exchange material of step (b); when a liquid ion exchange material is used, said liquid ion exchange material is the liquid ion exchange material of step (c); and when a mixture of said solid ion exchange material and said liquid ion exchange material is used, said mixture can be said treated slurry produced in step (a) or said mixture can be prepared by mixing said solid ion exchange material of step (b) with said liquid ion exchange material of step (c).    
     
     
         2 . The method of  claim 1  wherein said ion exchange material is said solid ion exchange material.  
     
     
         3 . The method of  claim 2  wherein an aqueous solution containing heavy metals and radionuclides is passed through a bed or column containing said solid ion exchange material.  
     
     
         4 . The method of  claim 2  wherein an aqueous solution containing heavy metals and radionuclides is processed batchwise by charging said solid ion exchange material into a volume of contaminated aqueous solution, agitating for a sufficient period of time, and conducting a liquid/solid separation to remove solids.  
     
     
         5 - 9 . (canceled)  
     
     
         10 . The method of  claim 1  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         11 . The method of  claim 1  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         12 . The method of  claim 1  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         13 . The method of  claim 1  wherein the ratio of clinoptilolite to alkaline solution in the slurry in step (a) is about 5 to about 50 grams clinoptilolite per 100 mL of alkaline solution.  
     
     
         14 . The method of  claim 1  wherein the alkaline compound in said alkaline solution is selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, tetraalkylammonium hydroxides, or mixtures thereof.  
     
     
         15 . The method of  claim 14  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         16 . The method of  claim 15  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         17 . The method of  claim 1  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.  
     
     
         18 . A process for producing an ion exchange material useful for removing heavy metals or radionuclides from an aqueous solution comprising: 
 (a) contacting clinoptilolite with an alkaline solution at a temperature of about 85° C. to about 300° C. and for a sufficient time to form a treated slurry comprising said ion exchange material comprising a solid fraction and a liquid fraction.    
     
     
         19 . The process of  claim 18  further comprising: 
 (b) separating the solid fraction from said treated slurry and washing the solid fraction to produce a solid ion exchange material; and    (c) recovering the liquid fraction of said treated slurry from step (b) to produce a liquid ion exchange material.    
     
     
         20 - 21 . (canceled)  
     
     
         22 . The process of  claim 18  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         23 . The process of  claim 18  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         24 . The process of  claim 18  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         25 . The process of  claim 18  wherein the ratio of clinoptilolite to alkaline solution in the slurry in step (a) is about 5 to about 50 grams clinoptilolite per 100 ml of alkaline solution.  
     
     
         26 . The process of  claim 18  wherein the alkaline compound in said alkaline solution is selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, tetraalkylammonium hydroxides, or mixtures thereof.  
     
     
         27 . The process of  claim 26  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         28 . The process of  claim 27  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         29 . The process of  claim 18  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.  
     
     
         30 . A solid ion exchange material for removing heavy metals or radionuclides from an aqueous solution, said solid ion exchange material being produced by the process comprising: 
 (a) contacting clinoptilolite with an alkaline solution at a temperature of about 85° C. to about 300° C. and for a sufficient time to form a treated slurry comprising a solid fraction and a liquid fraction,    (b) separating the solid fraction from said treated slurry and washing the solid fraction to produce said solid ion exchange material.    
     
     
         31 . The composition of  claim 30  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         32 . The composition of  claim 30  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         33 . The composition of  claim 30  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         34 . The composition of  claim 30  wherein the ratio of clinoptilolite to alkaline solution in the slurry in step (a) is about 5 to about 50 grams clinoptilolite per 100 ml of alkaline solution.  
     
     
         35 . The composition of  claim 30  wherein the alkaline compound in said alkaline solution is selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, tetraalkylammonium hydroxides, or mixtures thereof.  
     
     
         36 . The composition of  claim 35  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         37 . The composition of  claim 36  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         38 . The composition of  claim 30  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.  
     
     
         39 . A liquid ion exchange material for removing heavy metals or radionuclides from an aqueous solution, said liquid ion-exchange material being produced by the process comprising: 
 (a) contacting clinoptilolite with an alkaline solution at a temperature of about 85° C. to about 300° C. and for a sufficient time to form a treated slurry comprising a solid fraction and a liquid fraction; and    (b) separating said liquid fraction from said treated slurry to produce said liquid ion exchange material.    
     
     
         40 . The composition of  claim 39  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         41 . The composition of  claim 39  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         42 . The composition of  claim 39  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         43 . The composition of  claim 39  wherein the ratio of clinoptilolite to alkaline solution in the slurry in step (a) is about 5 to about 50 grams clinoptilolite per 100 ml of alkaline solution.  
     
     
         44 . The composition of  claim 39  wherein the alkaline compound in said alkaline solution is selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, tetraalkylammonium hydroxides, or mixtures thereof.  
     
     
         45 . The composition of  claim 44  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         46 . The composition of  claim 45  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         47 . The composition of  claim 39  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.