Disposal of Sodium Persulphate

[bucky]

I searched the archives, but I was unable to find a definitive answer.

I want to start etching PCBs, and sodium persulphate seems like the best option.  Is there any difference between ammonium persulphate and sodium persulphate, other than sodium allowing you to use etch pens?  Is one more toxic than the other?

After I am done with the solution, what is the best way to dispose of it?  I don't want to put it through the plumbing in my house.  I have a Household Hazardous Waste facility in my town, are they likely to accept it?  The HHW facility only operates from April to November, so I'd have to store it for a while.  How would I do this?  Could I seal it in a plastic container and keep it in my garage?

I have heard that adding baking soda neutralizes ferric chloride, does it do the same to persulphates?

Sorry for all the questions, and thanks in advance.

[Paul Perry (Frostwave)]

Keep it as long as you like. But don't seal it up tight, because if there is any active persulphate remaining (there will be!) it will slowly decompose & generate oxygen, so if the container is tightly sealed it might split.
The poisonous part is the copper in solution, but seeing as people regularly and deliberately run copper sulphate solution into drains to kill invading tree roots, I don't see much of a problem. ***except if you have a septic tank, anything that screws up the bacteria is bad news.

[bucky]

Is there anything I can add as a catalyst to use up any remaining persulphate?  If I can't seal the solution, how do I stop the toxic fumes from getting everywhere?

[toneman]

Dilute it with LOTS of H2O.

Pour it on some weeds.

Never down the drain, and *certainly* not into a septic tank.

At least with FeCL, U can rejuvenate it.
Don't think U can do that with Am or So Persulfate(?)

Then, There's always perfboard 

T

[Paul Perry (Frostwave)]

Persulphate has no toxic fumes. True, the powdered dust itself is an irritant, but in solution, it is no problem at all.