checking silver content

I have an old recovery unit that seems to be working, but I need to be
sure. How can I check the silver content of the bleach/fix after I run
the recovery unit? Thanks in advance.

nailer wrote:
if you ask, it probably is too difficult for you.
are you certain, your unit can do bleach-fix? it is much more
difficult than removing silver from a fixer.

the best determination of silver in bleach-fix is by titration with
thioacetamide agains silver electrode. Fixer can be titrated as is,
bleachfixes need to be modified.
is silver worth all that hassle?

It was worth $11.10/troy ounce Monday July 3, 2006. So maybe it is.
Perhaps a silver recovery unit will work on bleach-fix if you do not intend
to re-use the bleach-fix after desilvering it.

BX can be desilvered and reused after few more determinations and
adjustment of a composition and redox potential and pH.

On 5 Jul 2006 15:59:39 -0700, "DNT" wrote:

#I have an old recovery unit that seems to be working, but I need to
be
#sure. How can I check the silver content of the bleach/fix after I
run
#the recovery unit? Thanks in advance.


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Thanks for the input, but asking about something I've never dealt with
before doesn't mean it's too difficult for me. I don't plan to reuse
the blix, and the reason I need to remove the silver is it is against
the law to pour it down the drain. The epa has already been here. I
will save the silver and pour the rest out. I need to make sure that
what I pour out doesn't contain enough silver to get me in trouble with
the epa. I heard about test srtips from paper manufacturers, but I am
trying to find the cheapest way. Thanks again for everyones time. DNT
nailer wrote:
if you ask, it probably is too difficult for you.
are you certain, your unit can do bleach-fix? it is much more
difficult than removing silver from a fixer.

the best determination of silver in bleach-fix is by titration with
thioacetamide agains silver electrode. Fixer can be titrated as is,
bleachfixes need to be modified.
is silver worth all that hassle?
BX can be desilvered and reused after few more determinations and
adjustment of a composition and redox potential and pH.

On 5 Jul 2006 15:59:39 -0700, "DNT" wrote:

#I have an old recovery unit that seems to be working, but I need to
be
#sure. How can I check the silver content of the bleach/fix after I
run
#the recovery unit? Thanks in advance.

RENT wrote:

I will save the silver and pour the rest out.


You may be able to produce a sluge of of silver, likely
the sulfide, by adding H2O2 or Na2S. Safe? Couldn't say.
Ditto what's left in solution. Fix I know, Blix I know not.
How much of that stuff need be disposed? Dan

DNT wrote:

How can I check the silver content of the bleach/fix


Perhaps it would be more easily done if you were to bleach
then fix. An acidification of the fix with sodium bisulfate will bring
down the silver as sulfide and any excess sulfur as elemental sulfur.
I understand that the bisulfate is available at swimming pool supply
outlets as Ph minus. Dan

DNT wrote:
I have an old recovery unit that seems to be working, but I need to be
sure. How can I check the silver content of the bleach/fix after I run
the recovery unit? Thanks in advance.

In general the amount of silver allowed to go down the drain is quite
low. Most places require at least an electrolytic unit and a tailing
steel wool or iron mesh canister to reach the required ppm.

The yellow test strips are the cheapest way to verify some silver
content, but are only good down to about 0.1 g/l and the allowed
concentration is much lower than that. But they are useful in telling if
things are working; much better than playing chemist!

I have had good experience with cpac
http://www.cpacimaging.com/photomain.asp

gr