Ferric Chloride Disposal

[Simon Williams 3Participant @simonwilliams3]

Good afternoon one and all, many happy reurns of the weather. Or something.

I would value some advice on how the used PCB etchant can be disposed of safely and with due regard for the copper content. I have a small quantity (about 3 litres) of part used ferric chloride solution, which by now has some copper dissolved in it – presumably as copper chloride.

I am not on mains sewage, my drains go to a septic tank, though I guess tipping copper salts down the sewer would be irresponsible any way. But certainly I don't want to upset the happy little bacteria in my septic tank.

Is there a way of fixing the copper content of the solution (adding something that will catch the copper as an insoluble precipitate?). I would think the ferric ions would be OK to tip down the drain – it's only haemoglobin in bits. The brown goo in the bottom of the container is presumably iron oxide – rust?

My local recycling centre will dispose of chemicals – but it seems a bit irresponsible to dump the solution without telling them what it is, and the explanation will no doubt beggar any number of questions!

Any advice anyone?

[Simon Williams 3Participant @simonwilliams3]

Advice to dispose of used PCB etchant

[jimmy bParticipant @jimmyb]

I'd go the correct route and take it the recycling place.

We should all do the right thing with waste.

Jim

[Fowlers FuryParticipant @fowlersfury]

Simon,

It's very easy – put "ferric chloride disposal" into Google and you'll find many methods of treating the solution in order to dispose of it safely (as well as warnings about unsafe disposal).

[Tim StevensParticipant @timstevens64731]

Washing soda (sodium carbonate) will precipitate the copper as insoluble copper carbonate. But it will do much the same with the iron and any other metals in the mixture. This means you will have to add quite a lot (but washing soda is the cheapest chemical, really. Much cheaper and more effective than bicarbonate which is recommended by some). There will be quite a lot of fizzing, and froth, so the mixing should be in a bigger-than-needed container (made of plastic, I suggest).

Copper carbonate is a duck-egg blue solid, and ferrous carbonate green, while ferric carbonate is nearly black. So what you get as precipitate is going to vary in colour, but the main thing is that the solids are not soluble, and the remaining liquid (which will still include some Sodium Carbonate*) can go down the drain.

*you can tell the reaction has gone all the way by adding more sodium carbonate, and if it does not fizz at all, you are there.

The solid stuff is relatively harmless, so dry it and drop it in the bin. All the chemicals in it are found in nature, and some are used in jewellery, so if they are OK to hang round the neck of a queen, …

Cheers, Tim

[julian atkinsParticipant @julianatkins58923]

Hi Simon,

3 litres is a lot!

Can you pour it around the base of neighbours' leylandii trees?

Cheers,

Julian

[Neil WyattModerator @neilwyatt]

The old advice was chuck in enough plaster of paris to set it, then chuck it in the non-recyclable waste.

Neil

[Simon Williams 3Participant @simonwilliams3]

Good morning again, and thank you for that advice. I took a part used bag of plaster to the tip sorry recycling centre just before Christmas. Classic case of needing something a week after you've thrown it out!

Washing soda is cheap enough though, so I'll give it a go.

As always, thanks for the advice.

Simon

[BazyleParticipant @bazyle]

So you have copper salts – traditional fungicide for shrubs, and iron salts – traditional treatment for rhododendrons and hydrangeas. Seems more of an added bonus than a problem.

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