RE: Chelating Agents, Significants?

["John DeLaHunt" <jdelahunt@cc.colorado.edu>]

> What is the significants of .1% by weight of chelating agent in waste?
> Is the concern that metal will be released to the water table?

Standard answer #1:

It depends.

It depends on the metal, the chelating agent, the pH, the medium, the day
of the week, etc.

Generally speaking, chelating agents are used to isolate metals from a
solution by forming a stable complex with the metal.  Stable complexes of
this sort are generally insoluble in certain conditions (the right pH, for
example.)

If the metal is Na-23, for example, a low concentration wouldn't be a big
deal.  But if the metal is Hg-203, a low concentration would matter from
two waste disposal perspectives.

The chelating agent itelf may have some, ummm, disturbing properties.
Hydrides are sometimes used as chelating agents, for example. Orgnics are
used frequently, and some of these may or may not have toxic and/or
carcinogenic properties.

Short answer:  find out what metal they were chelating, with what, under
what chemical circumstances, and why.  That should help you determing the
next step.

I sincerely hope this helps.