Urea sorbent

Abstract

A sorbent polymer is provided that interacts or reacts with aqueous urea to aid the regeneration of a dialysate liquid. The sorbent polymer may include one or more specific functional groups bonded thereto. Such specific functional groups are selected from carboxylic acids, carboxylic acid esters, carboxylates, amides, dicarboxylic acids, dicarboxylic acid esters, and dicer boxylates to produce the desired urea sorbent.

1 . A polymer suitable for use as a sorbent for regenerating dialysate, the polymer including specific functional groups bonded thereto that interact with urea in a liquid at a pH of between 6 and 8 to remove urea from an aqueous solution, wherein the polymer is substantially insoluble in water and reacts with urea without releasing ammonia, wherein the reaction product of the polymer and urea is substantially insoluble in water, and wherein the polymer is selected from the group consisting of polymers having repeating units having the formula 
       
         
           
           
               
               
           
         
       
     
     
         2 . The polymer of  claim 1 , wherein the functional group includes at least two adjacent carbonyl groups. 
     
     
         3 . The polymer of  claim 1 , wherein the functional group comprises one of a dicarboxlic acid, a dicarboxlic acid ester, or a dicarboxalate. 
     
     
         4 . The polymer of  claim 1 , wherein the functional group comprises one of an oxalate, a pyruvate, a benzoate or an acrylic acid. 
     
     
         5 . A filter for regenerating dialysate comprising:
 a sorbent layer comprising a polymer having specific functional groups bonded thereto that interact with urea at a pH of between 5 and 10 to remove urea from an aqueous solution, wherein the polymer is substantially insoluble in water and interacts with urea in a predetermined temperature range and without releasing ammonia and wherein the reaction product of the polymer and urea is substantially insoluble in water; and   activated carbon for absorbing organic metabolites from the dialysate.   
     
     
         6 . The filter of  claim 5 , further comprising an anion exchange layer for removing anions from the dialysate. 
     
     
         7 . A polymer suitable for use as a sorbent for regenerating dialysate, the polymer including specific functional groups bonded thereto that react with urea at a pH of between 4 to 12 to remove urea from an aqueous solution, wherein the polymer is either soluble or substantially insoluble in water and interacts or reacts with urea in a temperature range of about 50° F. to 110° F. without releasing ammonia, wherein the reaction product of the polymer and urea is soluble or substantially insoluble in water, and wherein the polymer is selected from the group consisting of polymers having repeating units having the formula 
       
         
           
           
               
               
           
         
       
     
     
         8 . The polymer of  claim 7 , wherein the functional group includes at least one carbonyl group (C═O) either as a ketone, anhydride, ester, amido, or a combination of functional groups from two to 10 either adjacent or apart. 
     
     
         9 . The polymer of  claim 7 , wherein the functional group comprises one of a dicarboxylic acid, a dicarboxylic acid ester, a general dicarboxylate moiety or a combination of said functional groups. 
     
     
         10 . The polymer of  claim 7 , wherein the functional group comprises one of an oxalate, a pyruvate, a benzoate or an acrylic acid. 
     
     
         11 . The polymer of  claim 7 , wherein the functional groups react with urea at a pH of between 6 and 9. 
     
     
         12 . The polymer of  claim 7 , wherein the reaction product of the polymer and urea is insoluble in water. 
     
     
         13 . A dialysate regenerating filter for removing solids or liquids from dialysate comprising:
 a sorbent layer comprising a polymer having functional groups bonded thereto that interact or react with urea at a pH of between 4 to 12 and bind urea from an aqueous solution, wherein the polymer is either soluble or substantially insoluble in water and interacts or reacts with urea without releasing ammonia and wherein the interaction or reaction product of the polymer and urea is either soluble or substantially insoluble in water; and   activated carbon for absorbing organic metabolites from the dialysate.   
     
     
         14 . The filter of  claim 13 , further comprising an anion exchange layer for removing anions from the dialysate. 
     
     
         15 . The filter of  claim 13 , wherein the functional groups interact or react with urea at a pH of between 6 and 9. 
     
     
         16 . The filter of  claim 13 , wherein the polymer is insoluble in water. 
     
     
         17 . The filter of  claim 13 , wherein the interaction or reaction product of the polymer and urea is insoluble in water.