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Registered Member #29
Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500
I had some old FeCl3 etchant (including some added HCl for rejuvenating the solution to get a couple more etches out of it) that I needed to dispose of. I felt a bit guilty dumping the green-tinged still somewhat corrosive liquid down the drain, so I came up with the idea of neutralising it with a solution of NaOH.
My reasoning was that after reacting with an excess of NaOH, i.e.
The iron and copper hydroxides seem to precipitate out as a greenish yellow sludge. Given that they are not too soluble in water, perhaps they will be represent less of a toxic load on the environment.
Registered Member #29
Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500
Ooops... I forgot that there was a discussion before.. One uncertainty, tho': Given the solubility in water of Cu(OH)2 is not high, I presume the toxicity is much lower than for the soluble CuCl2...
The well known verderame (mixture of CuSO4 and Ca(OH)2 used in the past on vines in the wine-growing areas of Italy and still often used on ornamental plants and fruit trees) leaves green stains that do not wash away for months..... This material (probably similar to the copper component of my PCB etchant sludge) seems very insoluble in water....
I'll lock this thread since any further discussion of the topic can take place in the original thread.
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Neutralising spent FeCl3 etchant before disposal
