Process for preparing zirconium phosphate
AssigneeNational Research Development Corporation
InventorsDerek V. Nowell, Koteswararao Rentala
Life of this patent
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Abstract
Crystalline alpha zirconium phosphate Zr(HPO4).sub.2.H.sub.2 O, which can selectively remove ammonia and heavy metal ions from solution by ion exchange, is made by forming a room-temperature solution of zirconyl chloride ZrOCl.sub.2 in hydrochloric acid and adding sodium fluoride; the pH is now at most 1.6, the zirconium concentration is about 0.1M and the molar ratio sodium:zirconium is 5:1. Then, with rapid mixing, this composition is added to 15M phosphoric acid H.sub.3 PO.sub.4 (molar ratio phosphate:zirconium at least 3:1). Zirconium phosphate is precipitated.
Claims10
A process for preparing zirconium phosphate comprising:
- (1) forming a solution of zirconyl chloride in hydrochloric acid, the solution having a pH not exceeding 0.3;
- (2) adding sodium fluoride to a minimum molar ratio sodium:zirconium of 4:1 and subject to a maximum of 5.0:1 at a zirconium concentration of 0.1 M, of 5.2 at 0.07 M and 9 at 0.05 M;
- (3) ensuring that the solution is homogeneous, at a maximum pH of 1.6, and at a concentration of from 0.05 to 0.1 M in zirconium;
- (4) mixing the solution with phosphoric acid such that in the mixture the molar ratio phosphate:zirconium is substantially always at least 3, whereby zirconium phosphate precipitates;
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- (5) recovering said precipitated zirconium phosphate.
Dependencies are inferred from the claim text.