Sciencemadness Discussion Board

Removing sodium nitrate from sodium hydroxide.

Acyl - 11-6-2007 at 23:20

I cant seem to think up any feasible routes for this, any help is much appreciated.

not_important - 12-6-2007 at 00:28

Depends on the ratios of the two. I suspect that if the nitrate is only 10% of the total then it's not worth recovering.

Is it the sodium nitrate as such, or the NO3(-) you are after? If it is just recoving nitrate then consider adding KOH or K2CO3 in equal molar amounts with the NaNO3, KNO3 is less soluble which will may separation easier.

Assuming this is a solution, and that it's just the nitrate you're after and so have added a potassium salt, if the nitrate is in high enough proportion you can crystalise some of it out by evaporation. You'll need to keep air away, or at least CO2. And remember that strong hydroxide solutions etch glass and silicate ceramics. Decant the liquid from the crystals.

If you want as much of the nitrate as you can recover, then evaporate to dryness. Then add dry alcohol, use MgSO4 to dry ordinary denatured alcohol. It will take about 7 ml of alcohol to dissolve 1 g of NaOH, add a little extra. Warm and stir the mix, then let it settle and cool. Again, decant off the solution. Stir the solid nitrate with a little cold, dry alcohol, filter and wash it with more cold, dry alcohol.



evaporate to dryness, note that this will etch glass and ceramics and might best be finished

zeppelin69 - 25-6-2007 at 07:18

Actualy, I think he is after the hydroxide. If he is having the same problem I am, his only source for NaOH is draino, but it is contaminated with the nitrate. (and aluminum turnings, but that is easily removed.)