Rare earth metal compounds methods of making, and methods of using the same

Abstract

Rare earth metal compounds, particularly lanthanum, cerium, and yttrium, are formed as porous particles and are effective in binding metals, metal ions, and phosphate. A method of making the particles and a method of using the particles is disclosed. The particles may be used in the gastrointestinal tract or the bloodstream to remove phosphate or to treat hyperphosphatemia in mammals. The particles may also be used to remove metals from fluids such as water.

1 . A rare earth compound selected from the group consisting of rare earth oxychloride, a rare earth anhydrous oxycarbonate, and a rare earth hydrated oxycarbonate wherein the compound has an absorption capacity of at least 45 mg. phosphate per gram of compound.  
   
   
       2 . The compound of  claim 1  wherein the rare earth is selected from the group consisting of lanthanum, cerium, and yttrium.  
   
   
       3 . The compound of  claim 1  wherein the rare earth is lanthanum.  
   
   
       4 . The compound of  claim 1  wherein the compound is a particle with a porous structure.  
   
   
       5 . The compound of  claim 4  wherein the porous structure is made by total evaporation of a rare earth salt solution followed by calcination.  
   
   
       6 . The compound of  claim 5  wherein the evaporation is conducted in a spray dryer.  
   
   
       7 . The compound of  claim 5  wherein the evaporation temperature is between about 120.degree. and 500° C.  
   
   
       8 . The compound of  claim 5  wherein the calcination temperature is between about 400.degree. and about 1200° C.  
   
   
       9 . The compound of  claim 1  having a size between about 1 and about 1000 μm.  
   
   
       10 . The compound of  claim 9  wherein the compound is formed from individual crystals having a size between about 20 nm and about 10 μm.  
   
   
       11 . A method of treating hyperphosphatemia in a mammal comprising providing an effective amount of rare earth compound selected from the group consisting of rare earth oxychloride, a rare earth anhydrous oxycarbonate, and a rare earth carbonate hydroxide wherein the compound has an absorption capacity of at least 45 mg. phosphate per gram of compound.  
   
   
       12 . The method according to  claim 11 , wherein the compound is a rare earth carbonate hydroxide.  
   
   
       13 . The method according to  claim 12 , wherein the rare earth carbonate hydroxide is LaCO 3 OH.  
   
   
       14 . The method according to  claim 13 , wherein the compound has an absorption capacity of at least 45 mg. phosphate per gram of compound.  
   
   
       15 . The method according to  claim 14 , wherein the compound has a BET surface area of at least 10 m 2 /g.