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Author: Subject: Ammonia and sodium chromate seperation method
Thestock
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[*] posted on 6-1-2018 at 18:27
Ammonia and sodium chromate seperation method


Hi everyone.
Im hoping some of the more enlightened of the community could help me out.

Ive been trying to recycle some caravan/RV 3way fridges, These fridges are an absorption/ammonia style similar to Edison fridges. The issue with recycling these is that because they contain ammonia they cannot be simply dropped off at the scrap yard, Yet there is no places within the state that i can find to deal with them.

My research has shown me that there are 4 ingredients within the cooling unit of the fridge. Ammonia, Water, Sodium Chromate and hydrogen, the hydrogen will vent when i drain them but im still left with a mix of ammonia, water and the Chromate.

Does anyone know a way to remove the sodium chromate? Preferably a mechanical/physical method rather than titration etc

Thanks all

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ninhydric1
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[*] posted on 6-1-2018 at 19:50


Boil down the solution. The higher the temperature, the more ammonia that escapes. The ammonia gas can be led to a solution of an acid (vinegar works, as does HCl/ muriatic acid). The sodium chromate crystallizes out once the solution has been reduced significantly.



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Thestock
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[*] posted on 6-1-2018 at 23:09


I knew i came to the right place for a simple answer.
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[*] posted on 7-1-2018 at 05:18


If you just leave the solution in a shallow container outdoors (but out of the rain) the ammonia will dissipate and the water will evaporate leaving the chromate.
Someone on this forum might be happy to take that away for you.
If not, you can dispose of it by adding sodium bisulphite to reduce it to chrome (III) then add an alkali to precipitate the chromium as Cr2O3 which is relatively non toxic
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