Method for separation of 90Y from 90Sr

Abstract

Inorganic ion exchange materials for the separation of 90 Y from 90 Sr include chabazite, clinoptilolite, potassium pharmacosiderite, sodium titanosilicate and sodium nonatitanate. These materials are suitable for making a 90 Y generator that contains 90 Sr immobilized on an ion exchange column of the materials. The materials have a very high selectivity for 90 Sr, a very low selectivity for 90 Y, good radiation and thermal stability, low toxicity, fast reaction kinetics, and can be readily and reproducibly synthesized. A method is thus provided for eluting 90 Y from the ion exchange material with an eluant solution. The eluant solution is preferably aqueous, preferably has a pH greater than about 5, and preferably includes a chelating agent. Preferred chelating agents include gluconic acid, oxalic acid, iminodiacetic acid, nitrilotriacetic acid, citric acid, and combinations thereof.

What is claimed is:  
     
         1 . A process, comprising: 
 adsorbing strontium-90 onto an inorganic ion exchange material from an aqueous solution comprising a source of strontium-90; and    eluting yttrium-90 from the inorganic ion exchange material with a solution having a pH greater than about 5 and including a chelating agent.    
     
     
         2 . The process of  claim 1 , wherein the solution is aqueous.  
     
     
         3 . The process of  claim 1 , wherein the chelating agent is selected from gluconic acid, oxalic acid, iminodiacetic acid, nitrilotriacetic acid, citric acid, and combinations thereof.  
     
     
         4 . The process of  claim 1 , where the solution is neutral.  
     
     
         5 . The process of  claim 1  where the solution is alkaline.  
     
     
         6 . The process of  claim 1 , wherein the inorganic ion exchange material is selected from clinoptilolite, chabazite, potassium titanosilicate pharmacosiderite, sodium titanosilicate, sodium nonatitanate, and combinations thereof.  
     
     
         7 . The process of  claim 6 , wherein the aqueous solution includes a chelating agent selected from gluconic acid, oxalic acid, iminodiacetic acid, nitrilotriacetic acid, citric acid, and combinations thereof.  
     
     
         8 . The process of  claim 1 , wherein the inorganic ion exchange material is sodium nonatitanate prepared by reacting titanium isopropoxide and aqueous sodium hydroxide at a temperature between 100° C. and 250° C. for a period between 12 hours and 2 weeks.  
     
     
         9 . The process of  claim 1 , wherein the inorganic ion exchange material is sodium titanosilicate prepared by hydrothermally heating a titanium silicate gel in NaOH.  
     
     
         10 . The process of  claim 9 , wherein the titanium silicate gel is hydrothermally heated in 6M NaOH at 170° C. for 2 days.  
     
     
         11 . The process of  claim 1 , wherein the inorganic ion exchange material is a titanosilicate having the general formula:  
       M 3 H(AO) 4 (BO 4 ) 3   .x H 2 O  where: M is a cation selected from H, K, Na, Rb, Cs and mixtures thereof; 
 A is selected from Ti and Ge; and  
 B is selected from Si and Ge; and  
 x is a value between 4 and 6.  
   
     
     
         12 . The process of  claim 1 , further comprising forming the inorganic ion exchange material into pellets.  
     
     
         13 . The process of  claim 12 , wherein the pellets are formed with an average diameter between 0.1 and 1.0 mm.  
     
     
         14 . The process of  claim 12 , wherein the pellets are formed with an average diameter between 0.2 and 0.5 mm.  
     
     
         15 . The process of  claim 12 , wherein the pellets comprise a polymeric binder.  
     
     
         16 . The process of  claim 15 , wherein the polymeric binder comprises polyacrylonitrile as a binder.  
     
     
         17 . The process of  claim 12 , wherein the pellets comprise an inorganic binder.  
     
     
         18 . The process of  claim 17 , wherein the inorganic binder is amorphous.  
     
     
         19 . The process of  claim 17 , wherein the pellets comprise an inorganic binder selected from amorphous titanium dioxide, amorphous silica, amorphous zirconium oxide, and combinations thereof.  
     
     
         20 . A process, comprising: 
 (a) preparing a first solution including strontium-90;    (b) adsorbing strontium-90 from the first solution onto an inorganic ion exchange material; and    (c) allowing yttrium-90 to grow into the inorganic ion exchange material; and    (d) eluting yttrium-90 from the inorganic ion exchange material with a second solution including a chelating agent.    
     
     
         21 . The process of  claim 20 , further comprising: 
 repeating steps (c) and (d).    
     
     
         23 . The process of  claim 20 , wherein the inorganic ion exchange material is selected from clinoptilolite, chabazite, potassium titanosilicate pharmacosiderite, sodium titanosilicate, sodium nonatitanate, and combinations thereof.  
     
     
         24 . The process of  claim 20 , wherein the first solution has a pH greater than about 5.  
     
     
         25 . The process of  claim 20 , wherein the second solution has a pH greater than about 5.  
     
     
         26 . The process of  claim 20 , where the second solution is neutral.  
     
     
         27 . The process of  claim 20 , where the second solution is alkaline.  
     
     
         28 . The process of  claim 20 , wherein the second solution includes a chelating agent.  
     
     
         29 . The process of  claim 28 , wherein the chelating agent is selected from gluconic acid, oxalic acid, iminodiacetic acid, nitrilotriacetic acid, citric acid, and combinations thereof.  
     
     
         30 . The process of  claim 20 , further comprising: 
 (e) washing the inorganic ion exchange material to remove poorly bound strontium-90 prior to eluting.