From: Ed Stander (glassact@compuserve.com)
Date: 04/27/00-05:41:59 PM Z
I just received this today.
Needed:
Sodium Bisulfite
Potassium or Sodium Hydroxide
Calcium Hydroxide
Filter paper
Vacuum flask and funnel preferred but not absolutely necessary.
Place 2 -3 quarts of dichromate waste in a bucket. Add Sodium Bisulfite
until the solution turns color - add no more than 50 grams as this is the
max. needed for treatment
Stir solution completely then add either sodium or potassium hydroxide to
the solution. However, do not stir the waste until you have added an
additional 25 grams of calcium hydroxide to the solution. Stir well.
Check the color of the solution. It should have a milky green color. If
not, add more hydroxide. If you test pH, it should be around 12 at this
point. Let sit for at least 5 minutes to cool off.
Filter the solution through filter paper. This is preferably done with a
vacuum flask, as it will take a long time otherwise. The clear liquid at
this point is simply a base and can be sent down the sink. The filtered
material is precipitated chromium and should be double bagged and treated
as dangerous waste.
Hope this helps! Cheers, Ed Stander
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