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US 6,969,466 B1Granted
Purification of ammonia
AssigneePuritan Products, Inc.
InventorThomas C. Starner
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Abstract
Highly pure aqueous solution of ammonia, typically electronics grade for use in semiconductor manufacturing is prepared by passing a solution of ammonia through at least one cation exchange resin bed to remove substantially all of the cation contaminants; subsequently passing the cation exchange resin effluent through at least one anion exchange resin; and recovering an aqueous solution of ammonia product substantially free of ionic contaminants.
Claims11
A process for purifying an aqueous feed solution of ammonia containing cationic and anionic contaminants comprising the steps of:
- a) passing said aqueous feed solution of ammonia through at least one cation exchange resin bed so as to remove substantially all of the cationic contaminants at a flow rate of 35 to 50 gpm,
- b) subsequently passing the resulting aqueous solution through at least one anion exchange resin bed so as to remove substantially all of the anionic contaminants at a flow rate of 35 to 50 gpm;
- and
- c) recovering an aqueous solution of ammonia product substantially free of ionic contaminants.
1 more element
Dependencies are inferred from the claim text.