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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Og on July 08, 2010, 09:44:06 AM

Title: Zinc oxide and Phosphate
Post by: Og on July 08, 2010, 09:44:06 AM

Hi ,
I have quite a basic question .
When I'm exposing let say inorganic phosphate in the form of H2PO4 or
HPO4(-2), to a nanopowder of zinc oxide, Can I expect the phosphate to replace the oxygen ?
Or in the form of simple question , will ZnO nanoparticle can remove inorganic phosphate from a solution , and if so what are the condition (pH, etc. )
Thank you
Ohad

Title: Re: Zinc oxide and Phosphate
Post by: BluRay on July 14, 2010, 02:49:58 PM

In water solution, if the phosphate concentration is high, I think it's possible, with time, because ZnO is not completely insoluble:

ZnO + H₂O  ::equil::  Zn(OH)₂

Zn(OH)₂   ::equil::  Zn²⁺ + 2OH^-

As you see, a low pH favours this process.

So Zn²⁺ can slowly react with phoshate, giving zinc phosphate and which ones depends on pH: an high pH favours the precipitation of more insoluble phosphates so an high pH favours this process.

In conclusion the pH is critical. A meaningful calculus should consider kinetics too so the answer is not very easy. I can only say that what you think it's possible.