Method for removing heavy metals and radionuclides

Abstract

A solid ion-exchange material useful for removing heavy metals or radionuclides from an aqueous or gaseous solution comprising a modified clinoptilolite, and methods of using same are provided.

1 . A method for removing heavy metals or radionuclides from an aqueous and/or gaseous solution comprising contacting said aqueous solution and/or gaseous solution 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 and/or gaseous solution containing heavy metals or radionuclides is passed through a bed or column containing said solid ion exchange material.  
     
     
         4 . The method of  claim 2  wherein an aqueous and/or gaseous solution containing heavy metals or radionuclides is processed batchwise by charging said solid ion exchange material into a volume of contaminated aqueous or gaseous solution, agitating for a sufficient period of time, and conducting a liquid/solid separation or gas/solid separation to remove solids.  
     
     
         5 . The method of  claim 1  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         6 . The method of  claim 1  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         7 . The method of  claim 1  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         8 . 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.  
     
     
         9 . 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.  
     
     
         10 . The method of  claim 9  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         11 . The method of  claim 10  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         12 . The method of  claim 1  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.  
     
     
         13 . A process for producing an ion exchange material useful for removing heavy metals or radionuclides from an aqueous or gaseous 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.    
     
     
         14 . The process of  claim 13  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;    
     
     
         15 . The process of  claim 13  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         16 . The process of  claim 13  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         17 . The process of  claim 13  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         18 . The process of  claim 13  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.  
     
     
         19 . The process of  claim 13  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.  
     
     
         20 . The process of  claim 19  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         21 . The process of  claim 20  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         22 . The process of  claim 13  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.  
     
     
         23 . A solid ion exchange material for removing heavy metals or radionuclides from an aqueous or gaseous 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.    
     
     
         24 . The composition of  claim 23  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         25 . The composition of  claim 23  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         26 . The composition of  claim 23  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         27 . The composition of  claim 23  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.  
     
     
         28 . The composition of  claim 23  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.  
     
     
         29 . The composition of  claim 28  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         30 . The composition of  claim 29  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         31 . The composition of  claim 23  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.  
     
     
         32 . A liquid ion exchange material for removing heavy metals or radionuclides from an aqueous or gaseous 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.    
     
     
         33 . The composition of  claim 32  wherein step (a) is conducted under a pressure greater than the ambient pressure.  
     
     
         34 . The composition of  claim 32  wherein the alkaline solution used in step (a) has a concentration greater than about 0.5 M.  
     
     
         35 . The composition of  claim 32  wherein step (a) is conducted at a temperature of about 100° C. to about 125° C.  
     
     
         36 . The composition of  claim 32  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.  
     
     
         37 . The composition of  claim 32  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.  
     
     
         38 . The composition of  claim 37  wherein said alkaline compound is an alkali metal hydroxide.  
     
     
         39 . The composition of  claim 38  wherein said alkali metal hydroxide is sodium hydroxide or potassium hydroxide.  
     
     
         40 . The composition of  claim 32  wherein the contacting time of step (a) is about 30 minutes to about 4 hours.  
     
     
         41 . A solid ion-exchange material useful for removing heavy metals or radionuclides from an aqueous or gaseous solution comprising a modified clinoptilolite comprising: 
 (a) a silicon/aluminum (Si/Al) concentration ratio of about 1:1 to about 4:1, and    (b) a sodium (Na) concentration of 20,000 mg/kg to about 140,000 mg/kg.    
     
     
         42 . The composition of  claim 41  wherein the Si/Al concentration ratio is from about 1:1 to about 3:1.  
     
     
         43 . The composition of  claim 41  wherein the Si/Al concentration ratio is from about 1.5:1 to about 3:1.  
     
     
         44 . The composition of  claim 42  wherein the Na concentration is of about 40,000 to about 100,000 mg/kg.  
     
     
         45 . The composition of  claim 43  wherein the Na concentration is of about 50,000 to about 80,000 mg/kg.  
     
     
         46 . The composition of  claim 41 , which further comprises Ca with a concentration from 15000 mg/kg to 30000 mg/kg.  
     
     
         47 . The composition of  claim 46 , which further comprises K, with a concentration from 5000 mg/kg to about 20,000 mg/kg.  
     
     
         48 . A liquid ion-exchange material useful for removing heavy metals and/or radionuclides from an aqueous or gaseous solution comprising: 
 (a) about 2,500 mg/L to about 50,000 mg/L Si;    (b) about 60 mg/L to about 1,200 mg/L Al; and    (c) about 10,000 mg/L to about 200,000 mg/L hydroxide ion.    
     
     
         49 . The composition of  claim 48  wherein the Si concentration is about 10,000 to about 40,000 mg/L.  
     
     
         50 . The composition of  claim 48  wherein the Si concentration is about 20,000 to about 30,000 mg/L.  
     
     
         51 . The composition of  claim 49  wherein the Al concentration is about 200 to about 1,000 mg/L.  
     
     
         52 . The composition of  claim 50  wherein the Al concentration is about 300 to about 700 mg/L.  
     
     
         53 . The composition of  claim 52  wherein the hydroxide concentration is about 50,000 to about 15,000 mg/L.