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How to neutralize FeCl3

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GODSFUSION

Sun Apr 16 2006, 08:02AM

Registered Member #157 Joined: Sun Feb 12 2006, 08:00PM
Location:
Posts: 76

How do i go about neutralizing my used ferric chloride. Or where do i go to dispose of it?

- wayne -

Hazmatt_(The Underdog)

Sun Apr 16 2006, 06:57PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

There are a lot of different ways you can do this, most of which create a huge mess. That's why I would recommend keeping an etch-tank if you etch a lot of circuit boards.

1. Bicarbonate from pool supply in 1lb. baggies. This makes a pretty big mess, but if you use enough bicarbonate, then it becomes a DRY mess and you can throw away the Iron Hydroxide because its about as harmless as rust.

2. Red Devil Lye. This has no Aluminum chunks in it, you could even use it to make developer insted of buying the expensive stuff. I think the molarity of the developer is 1.8, but id have to get back to you on that one.
Anyways, the Lye will make an Aqueous mess which you can flush, just don't spill on the carpet when in transit.

I have done both of these. Again, I think getting an etch bucket will save you a big headache.
I return used etchant right back into the tank with no ill effects.

Wolfram

Sun Apr 16 2006, 11:37PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

Regarding what concentration of NaOH to use for developing; 20g per liter of water seems to be most common.

GODSFUSION

Mon Apr 17 2006, 04:08AM

Registered Member #157 Joined: Sun Feb 12 2006, 08:00PM
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Posts: 76

well i have a 5 gallon bucket with a fishtank airator and tank heter ijn it, part way down i put bolts through the sides to hold the airator and heater uprite & in place on a circular piece of plywood. Off the plywood is a clothes hanger witch i hook the PCB to and just lower it all into the FeCL3. I got it used (the FeCL3) from a local highschool that was getting rid of it. they said they used it for chemistry "art" projects.

About the Bicarbonate, do i just mix it in untill it all becomes dry...? Can i flush the dry stuff down the toilet?

- Wayne -

- Wayne -

Simon

Mon Apr 17 2006, 06:06AM

Registered Member #32 Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549

The real nasty for disposing of spent etchant is Cu2+. If you check MSDSs, most copper compounds (like copper sulfate) are labelled "Harmful to the environment", which means you shouldn't just tip them down the sink.

I'm not sure about the solution to the problem. I've still got my etchant in the bottles it came in.

Hazmatt_(The Underdog)

Mon Apr 17 2006, 08:14AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Don't flush the dry mass down the toilet, it will clog your pipes.

The Copper Chloride is known to be toxic, although I had to dig through one of my older chemistry books before I found it stated. Copper Compounds are stated in my Dangerous Properties book to be a slight to moderate risk when exposed. However, it does describe some very painful poisoning symptoms.

Bolts in the bucket, I think that's a very bad way to do things. You can have some creepage of the etchant through the holes, and the bolts unless Nylon will be destroyed shortly.
Welding the plastic would have been a much better option, and if that's not possible, a self jigging wood circle would have been my second option. But since you already have it, give it a shot and see what really happens.

...

Mon Apr 17 2006, 10:40PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Not to sound like an envirmentalist, but my mom works at the treatment plant so...
Please don't dump it down the drains. Heavy metals do not get taken out in normal treatment plants, and goes pretty much strait through to the outfall (depends on where you live, could be ocean, river, irrigation, groundwater, or even drinking water). Sure that one bucket you have might not make a diference, but...

If you live in the US, you should take it to a 'household hazardous waste roundup'. Google it and you city name to figure out where and when your's is. I assume that most other countries have something similar...

If you can't get to one of those, I would suggest adding enough backing soda (bicarbonate) that the ph is >7, put it in a sealed container, and send it off you your landfill...

I suppose if all of the copper is precipated out it will get taken out with the 'sludge' from a treatment plant, but then that is probably going back on your farms...

Just to give an idea as to the toxcisity of the Cu2+ ion... A common algecide for pools/spas is cupper(II)sulfate. It is used at a .5ppm concentration.

Electroholic

Tue Apr 18 2006, 12:54AM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

y not just use some base to ppt the Cu?
then just filter it

GODSFUSION

Tue Apr 18 2006, 01:40AM

Registered Member #157 Joined: Sun Feb 12 2006, 08:00PM
Location:
Posts: 76

This is what it is, the FeCL3 its self dosent touch the bolts they just hold up the lid that has the Airator and heater.

1145323736 157 FT1630 Fecl3

I understand your concern for the environment thats why ive asked how to neutralize the stuff so i can safely dispose of it.

Hazmatt_(The Underdog)

Tue Apr 18 2006, 02:33AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

The bolts will still get attacked by the FeCl3 mist, even if there is little creepage. You will want to put some silicone over them or coat the entire bolt in some lacquer

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