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How To remove NaCl from solution

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rcarbon:
I did tried this alkali precipitation method but it did not worked out on Pt.
However this method is very well workable when using Pd and Rh

Babcock_Hall:
Would it be helpful to exchange the NaCl into NaNO3?

rcarbon:
aim is to get halide free Platinum Nitrate, by any possible method

Jorge Stolfi:

--- Quote from: rcarbon on February 19, 2019, 12:05:40 PM ---aim is to get halide free Platinum Nitrate, by any possible method

--- End quote ---

Nosy non-chemist here again. What about this:

1. Evaporate the solution until just before the Pt nitrate starts to crystallize out.  If some NaCl crystallizes out first, all the better.

2. Add some polar solvent to the liquid that does not react with the HNO3 and the Pt nitrate, and dissolves the latter better than NaCl. Most of the NaCl should precipitate out.

3. Evaporate the remaining liquid again to crystallize most of the Pt nitrate, but not enough for the remaining NaCl to crystallize. 

4. Separate the remaning liquid and repeat from step 2.

Makes sense?

... until  the Pt nitrate is all crystallized

AWK:

--- Quote from: rcarbon on February 19, 2019, 10:07:21 AM ---I did tried this alkali precipitation method but it did not worked out on Pt.
However this method is very well workable when using Pd and Rh

--- End quote ---
At least this publication in my link and 3 patents (found in google patents) use alkali precipitation method with success.
Try to change some parameters, eg temperature, time, concentration and excess of nitric acid (I understand that the problems are at this stage of the synthesis).
The alkali precipitation method will remove chlorides almost completely if you manage to master them.
Fractional crystallization (suggested by Jorge Stolfi) is extremely labor-intensive (especially on a small scale) and not always effective due to the possibility of forming co-crystals (we do not know all the properties of platinum(IV) nitrate except its good solubility in water).

How did you check that the method you describe allows you to get platinum(IV) nitrate? It is used from time immemorial (over 90 years) for PtO2 synthesis without isolation of nitrate.

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