Reactions of Phosphate with Soluble and Exchangeable Nickel1, 2
- P. F. Pratt,
- F. L. Bair and
- G. W. McLean3
When solutions of NiCl2 and KH2PO4 were titrated with NaOH, the immediate reaction product was an amorphous precipitate having a composition corresponding to 6NiHPO4 · Ni(OH)2 · 7H2O or 4NiHPO4 · Ni3(PO4)2 · 9H2O. At all pH values < 7, the precipitate was free of Ni(OH)2 or had a constant Ni(OH)2 content, but at pH values > 7, the Ni(OH)2 increased with increase in pH. When the amorphous precipitate was incubated at 25°C., crystalline products began to appear at 4 weeks and at 12 weeks the crystallization appeared to be complete. The main crystalline product was Ni3(PO4)2 · 8H2O. Crystallization was accompanied by acidification and also by a large reduction in the solubility of Ni. In the pH range of 6.5 to 7 the solubility of Ni was reduced to about 2 ppm.
Nickel-saturated clays treated with phosphate showed the same reactions as found in solution. The exchangeable Ni was reduced to about 3% saturation.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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