PCB Etchant Disposal - Page 1
Forum section: electronics / projects

author: AndrewA
author_rank: Newbie
timestamp: July 18, 2014, 12:40:21 pm
content: Good evening allI develop my own PCBs using Press'n'Peel and Ammonium Persulphate.The etchant solution I use has become rather saturated with copper (having been used quite a few times) and I am thinking I need to dispose of it.I have read other websites suggesting everything from throwing it out on the front lawn as fertiliser to flushing it down the toilet.But now I am after a *sensible* resolution to getting rid of it.Any suggestions?

author: sleemanj
author_rank: Super Contributor
timestamp: July 18, 2014, 12:43:49 pm
content: Make it into a solid, then put it in the rubbish.

author: AndyC_772
author_rank: Super Contributor
timestamp: July 18, 2014, 12:55:05 pm
content: Cat litter?

author: ConKbot
author_rank: Super Contributor
timestamp: July 18, 2014, 12:55:42 pm
content: I'd definitely not throw it on the lawn as copper ions are generally a biocide and not fertilizer, hence why boat bottom paint can be loaded with copper to keep barnacles off. Since the solution is all aqueous you just have a pool of copper, sulfate, persulfate and ammonium ions floating around. Adding something to make an insoluble copper salt and collecting that should make the remainder safe enough to flush. Copper carbonate isnt soluble in water, I'd expect that adding sodium bicarbonate (baking soda) would do this, (along with yielding a bunch of CO2 making it fizz) But I'm not as sharp with chemistry as I used to be, so I'd take a 2nd opinion on that first.

author: janoc
author_rank: Super Contributor
timestamp: July 18, 2014, 01:30:38 pm
content: "throwing it out on the front lawn as fertiliser"Jeeze, copper compounds are used to fight various fungi and moulds. That is most certainly no "fertiliser"! Ammonium persulphate itself is also classed as hazardous and strong oxidizer. You shouldn't flush anything like this, neutralized or not neither.Put it in a labelled bottle and bring it as hazardous waste to your local waste disposal yard. They usually have collection tanks and facilities to take such stuff in, sometimes for a small fee.

author: N2IXK
author_rank: Frequent Contributor
timestamp: July 18, 2014, 01:35:05 pm
content: Copper sulphate is actually sold here in the US specifically to be poured down drains or flushed down toilets to kill off tree roots that infiltrate sewer lines causing blockages. You use about a pound of the stuff at a time with minimal water so it lays in the sewer line to contact the roots.I really cant see a little bit of spent etchant being a problem if well diluted with water.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: July 18, 2014, 01:43:05 pm
content: except not being quite spent it can etch your plumbing

author: N2IXK
author_rank: Frequent Contributor
timestamp: July 18, 2014, 02:37:16 pm
content: Hence the "well diluted with water" part....

author: tjb1
author_rank: Regular Contributor
timestamp: July 18, 2014, 02:38:56 pm
content: Quote from: f5r5e5d on July 18, 2014, 01:43:05 pmMost drains are PVC and/or cement.

author: con-f-use
author_rank: Unknown
timestamp: July 18, 2014, 02:51:53 pm
content: It's still poisonous to water organisms, pollution and might etch some of the metal parts of your sewage. It's nasty and you'd be a dick to do it.I couldn't tell if you are etching with the normal HCL+H2O2, persulfate or Fe-3-Cl. If your etchant is HCl based, you can"revive"it adding peroxide or acid. If that fails, you can, filter the solid out of your neutralized liquid, put the liquid down the drain and the solid in the waste as described in my. I've been told the same works with sodium bicarbonate (baking soda) for persulfate based etchant. I rather doubt that because I'd assume the reaction needs an acidic component, but I'm not a chemist.Edit: Sorry saw the "Amonium Persulfate" too late.

author: Refrigerator
author_rank: Super Contributor
timestamp: July 18, 2014, 03:37:13 pm
content: With used etchants you just add baking soda in the etchant until it stops bubbling (the etchant will be neutralized) and then drain it down the toilet.Anyways, if you're getting new etchant i'd suggest copper chloride, once it gets saturated with copper you can simply add more water, also you can make it stronger by bubbling it with air.

author: nctnico
author_rank: Super Contributor
timestamp: July 18, 2014, 03:50:05 pm
content: Actually FeCl slowly converts into CuCl (copper chloride). Adding some HCl regenerates the CuCl. That way you can use the same etchant for decades.

author: Bored@Work
author_rank: Super Contributor
timestamp: July 18, 2014, 04:56:29 pm
content: Quote from: AndrewA on July 18, 2014, 12:40:21 pmYes, don't do this etching shit at home. Get your PCBs made.And whenever you see some youtube wanker or maker propagating that etching your own PCB is so great and manly, well, just remember these people are just stupid wankers.And no, diluting, neutralizing or pissing into it does not reduce the poisonousness to water organisms. It does not belong down the drain, whatever some dickheads try to tell you.Contact your local wast disposal agency, council, or whoever is responsible for waste disposal and management in your area. Ask for the proper way (read: where to deliver it) to dispose of it.

author: con-f-use
author_rank: Unknown
timestamp: July 18, 2014, 05:26:14 pm
content: Quote from: Bored@Work on July 18, 2014, 04:56:29 pmI find it useful for prototyping work and one-off projects that use smd components. I can etch a board in 20 minutes for about 3,- €. In some cases I don't want to wait two weeks for my boards to arrive. But I admit most of my projects use boards from fab houses. Am I a stupid wanker now?

author: poorchava
author_rank: Super Contributor
timestamp: July 18, 2014, 08:41:26 pm
content: I just flush it in the toilet. 100ml of Hcl + peroxide + some copper won't hurt anybody, and if anything - it will slown down scale buildup.If you were to dispose of 50 liters of that stuff - that could be a problem, but a hobby-grade etching bath? No reason to bother.

author: SteveyG
author_rank: Unknown
timestamp: July 18, 2014, 08:54:03 pm
content: Quote from: Bored@Work on July 18, 2014, 04:56:29 pmCalm down hun. There's nothing wrong with etching your own PCBs, I used to etch double sided PCBs and have them assembled in a weekend. I'd have needed to wait a few days for PCBs to be made and 100x the cost.

author: GreyWoolfe
author_rank: Unknown
timestamp: July 18, 2014, 09:07:22 pm
content: Con-f-use, I guess I officially join you in the ranks of stupid wankers. I do small, fairly simple projects and I, too, would rather make my own than send it out. You know, I could comment about how I believe that people who denigrate others do so to cover up their own shortcomings, but then I would probably be labeled a stupid wanker. Oh wait, I already have been.At least I follow in the footsteps of people like Alan, W2AEW, who makes all his own boards for his project videos-good company.

author: Bored@Work
author_rank: Super Contributor
timestamp: July 18, 2014, 09:12:33 pm
content: The point is you attract even more stupid wankers, as you can see in this thread: Those suggesting to just flush the waste down the drain.So instead of being responsible amateurs you promote irresponsible behavior by claiming etching your own PCBs is the right thing to do.

author: nctnico
author_rank: Super Contributor
timestamp: July 18, 2014, 09:48:51 pm
content: Let's say that flushing chemical waste down the toilet is a well established practice in less civil countriesA little bit of copper doesn't hurt but all the small bits add up to a large amount. In my own country they had to spend hundreds of millions of euro to clean up old chemical waste dumps from times where people thought a little bit of copper didn't hurt anyone. In some cases they had to tear down entire neighbourhoods. So that is why they got anal about chemical waste disposal!About etching at home: with the cheap Chinese fab houses (which flush their waste down their toilet anyway) it is hard to justify etching your own boards. OTOH if you need something quick etching your own boards is the about the only way.

author: farrell
author_rank: Contributor
timestamp: July 18, 2014, 09:56:36 pm
content: The waste products of PCB etching aren't great for the environment, but let's also be realistic. A hobbyist going through a quart (or liter, if you prefer) of etchant per year is no big deal. Even if they pour the waste down the drain. It's not good, but it's not like they are fab houses using gallons of the stuff each day. Don't forget the harm you do to the environment by driving, or running your air conditioner, or having your trash sit in a landfill.

author: GreyWoolfe
author_rank: Unknown
timestamp: July 18, 2014, 10:09:58 pm
content: I, for one, do not dispose of used etchant down the drain. I save it for when my town has free hazardous waste disposal day so it doesn't go down the drain, along with old paint cans, etc. I am not claiming that etching my own boards is the right thing to do. I am saying that, for me, making my own simple, little, stupid project boards is easiest for me. Hey Bored, I'm not buying into not doing things your APPROVED way makes me a wanker. Just curious, is the air kind of thin, sitting up there on your high horse, looking down at us "wankers"? Just asking.

author: AndrewA
author_rank: Newbie
timestamp: July 18, 2014, 11:34:49 pm
content: The total amount of etchant is probably about a litre and a half.I did ring the local city council and they said they would charge me A$80.00 to dispose of it for me, and that would only be a day next September (apparently they have a toxic chemicals disposal day).Alternatively they said I could flush it in small amounts with no ill side effects.I might just put it in another container and wait until September and do the right thing.

author: AndrewA
author_rank: Newbie
timestamp: July 18, 2014, 11:43:33 pm
content: Yes. Local city council wanted $60.00 to dispose of it at the waste collection day in September. They also said that a little bit could be dropped into the sewerage system without issue.Think I'll store it and wait for September and bite the bullet.

author: N2IXK
author_rank: Frequent Contributor
timestamp: July 18, 2014, 11:48:39 pm
content: A $60 charge to drop it off yourself? That sucks.They have the hazmat collection days twice a year around here, and drop offs are free as long as you have proof of county residency. They do make you sign a form stating that you are not disposing of waste from a business (they need to hire their own disposal service), and I assume they might investigate if you showed up with industrial quantities of nasty stuff.I have dropped off some fairly "exotic" stuff (PCB transformers/caps, ignitron tubes and contactors with pounds of metallic mercury in them, radium painted panel meters, and a few bits of beryllium oxide ceramic) over the years, and have never been turned away or questioned about any of it.

author: max666
author_rank: Frequent Contributor
timestamp: July 19, 2014, 12:31:31 am
content: A little bit of etching solution down the drain (heavily diluted), might not cause major harm, but that doesn't mean it's the right thing to do.Copper is a heavy metal and as such should not be disposed down the drain. At least not in solution; precipitating would be a good idea.Fortunately in my country you can always give off problem waste in household quantities at the recycling centre and three times a year they even drive around and have a mobile problem waste collection, all free of charge.

author: janoc
author_rank: Super Contributor
timestamp: July 19, 2014, 01:09:31 am
content: Quote from: Bored@Work on July 18, 2014, 09:12:33 pmCalm down and get off your high horse, mate. Etching your own boards is not "irresponsible behavior". Not disposing of the spent etchant properly (whether because of laziness or ignorance) is a different story, but that is why there is this discussion, no? So that hobbyists don't do stupid things with the chemicals. There are some way worse things available in your average gardening supply store or drugstore than an ammonium persulfate or some copper compounds and we are still all alive.Calling people names because they don't want to spend 20-30 bucks and wait 3 weeks for a silly breakout board is really uncalled for. If you have a board house next door, don't mind spending a hundred bucks on a large board for your hobby or can piggyback on a batch at work, fine. Not everyone has that possibility. Not to mention that homebrewing stuff is a time honored tradition - or should we rather all just shut up and only keep buying pre-made stuff like the good sheep?Sheesh ...

author: janoc
author_rank: Super Contributor
timestamp: July 19, 2014, 01:24:49 am
content: Quote from: nctnico on July 18, 2014, 09:48:51 pmThe problem with the Chinese houses is the turnaround time (about 3-4 weeks to France from places like iTead or Seed) and then minimal quantities. I almost never need 10 boards but that is the minimal quantity they allow (or rather a single board costs the same as 10). Minimal orders tend to be around $25-$30 for 10 board from these places. It is not that expensive, but it adds up quickly - it is a hobby for me, so an expense like that is hard to justify for every board I need (mostly various breakouts, adaptors, etc.).I am still sending out stuff requiring tight tolerances or double sided boards - that's just not worth the hassle for me, even though I could probably do double sided if I really had to.

author: wagon
author_rank: Frequent Contributor
timestamp: July 22, 2014, 12:37:00 pm
content: What about leaving the used solution in a suitable covered container (to keep birds and things out), outside in the sun until all of the water is gone? Then bottle up the dried residue and put it in the bin. It might take months, but better than flushing, surely.

author: max666
author_rank: Frequent Contributor
timestamp: July 22, 2014, 06:34:29 pm
content: I'm not chemist enough to know for sure, but I would think you could reduce (as in deoxidize) the copper out of solution by putting in a piece of steel wool.This way the iron would replace the copper in the solution and you would end up with metallic copper and an iron-ammonium-persulphate solution (which would be heavy metal free).

author: aroby
author_rank: Regular Contributor
timestamp: July 22, 2014, 11:18:19 pm
content: Back in the 70s / early 80s, in the UK, my family used to own a photo processor. Not a mini-lab, but a sizable plant that would process film and prints from all the chemists, photo stores etc. in a 200 mile radius. All the used chemicals went down the drain. To be honest, I don't think anyone even thought about the impact of that.I doubt that disposing of small amounts of etchant via the toilet will cause any real harm, however I think buying some cheap cat litter, pouring the solution into that and letting it sit outside to dry before disposing in the garbage would be the best route.

author: N2IXK
author_rank: Frequent Contributor
timestamp: July 22, 2014, 11:27:33 pm
content: Quote from: aroby on July 22, 2014, 11:18:19 pmHe didn't even send them out for silver recovery? Waste of money, even beyond the impact on the environment.

author: Stonent
author_rank: Super Contributor
timestamp: July 23, 2014, 02:28:41 am
content: I read once that those chemicals are used in swimming pools for algaecide purposes. So diluting it with a few thousand gallons of water seems to make it safe enough that it can enter the sewer system.Though it seems you could easily boil it down in a glass dish until the water is gone and then you're just left with a powder which could easily be put into a small plastic bottle and put on a shelf until you decide what to do with it. But again contacting a local school chemistry department may come up with a good answer.

author: janoc
author_rank: Super Contributor
timestamp: July 23, 2014, 10:03:19 am
content: Quote from: Stonent on July 23, 2014, 02:28:41 amI don't think ammonium persulfate or copper compounds are used to combat algae in swimming pools. Copper sulfate is used as fungicides and herbicides in agriculture, e.g. to treat grapes, but not where humans can come directly in contact with it. There are some chelated copper based products for pool care, but that is a fairly different thing. In general, copper compounds are toxic to humans and you don't want to swim in them!Quote from: Stonent on July 23, 2014, 02:28:41 amDrying it out (slowly!) and then disposing of the sludge as hazardous waste is likely ok. However, I certainly wouldn't boil it unless you are equipped and properly trained to handle it - ammonium persulfate is a strong oxidizing agent, it attacks a lot of materials. Heating it up will increase the reactivity even more and the potential that the boiling chemical splashes or the glassware bursts (not uncommon when heated!) spraying this thing all over the place is really a disaster waiting to happen.

author: Unknown
author_rank: Unknown
timestamp: July 23, 2014, 10:50:02 am
content: Quote from: janoc on July 23, 2014, 10:03:19 amYeah, it's various copper compounds that are used as algaecides/herbicides. It's actually not too toxic to most vertebrates (IIRC 1 or 2mg per L is acceptable in water for human consumption), though it's more toxic for fish & reptiles/etc.It is however pretty toxic to invertebrates, particularly aquatic inverts. From memory, fractional ppb is enough for 100% mortality in some species.(The mechanism varies but it's usually some variation of preferential binding with haemocyanin in invert 'blood' cells, which explains why vertebrates with haemoglobin are less affected).

author: BRetonDP
author_rank: Contributor
timestamp: July 23, 2014, 07:53:55 pm
content: It has recently come to my attention that products like this exist (I know squat about chemistry, tbh). It's a ferric chloride neutralizer solution.http://www.maplin.co.uk/p/pcb-etchant-neutraliser-n18kh?t=216430661&c=AffilWin86732&Does anyone have any idea if these kind of things work? I guess there's not much science to it, but I wouldn't know.

author: philpem
author_rank: Frequent Contributor
timestamp: July 23, 2014, 09:11:24 pm
content: Quote from: BRetonDP on July 23, 2014, 07:53:55 pmIf you dig around the web (search for the manufacturer of the chemical -- Chiltern Connections Ltd. -- who incidentally supply most of Maplin's PCB etching products) you can find an MSDS for that stuff:http://www.chilternconnections.co.uk/ZENCART/HANDSSHEETS/CCL%20Alpha/FCEN_MSDS.pdfTurns out it's 100% sodium carbonate. In other words - washing soda. You can buy it for pennies at your local Wilko or similar hardware shop, and probably a fair few supermarkets too.

author: N2IXK
author_rank: Frequent Contributor
timestamp: July 23, 2014, 11:37:42 pm
content: The Maplin site says they will only sell their overpriced washing soda to buyers over 18. Is there some illicit/destructive use for Na2CO3 that I am not aware of?

author: Stonent
author_rank: Super Contributor
timestamp: July 24, 2014, 02:30:01 am
content: Quote from: philpem on July 23, 2014, 09:11:24 pmI used that to my advantage recently when I went to purchase some coffee maker cleaner and saw it was $5 for maybe an ounce of cleaner. I googled it and found that it was just 100% sodium carbonate so I headed over to the soap aisle and bought a 2 pound box for $2.

author: aargee
author_rank: Frequent Contributor
timestamp: July 24, 2014, 06:45:19 am
content: Talking about getting your boards made in China at the cheapest/fastest place, I guess no one really knows (or cares?) what they might be doing with their waste?I think it's fine that you want to make your own boards locally and just as fine that you seek an environmentally safe way to dispose of the byproducts.

author: janoc
author_rank: Super Contributor
timestamp: July 25, 2014, 02:19:01 pm
content: Quote from: N2IXK on July 23, 2014, 11:37:42 pmPut it in a plastic bottle with some vinegar or citric acid, shake and put a stopper in? Instant terrorist weapon of mass destruction!

author: janoc
author_rank: Super Contributor
timestamp: July 29, 2014, 10:29:13 pm
content: Quote from: AcHmed99 on July 25, 2014, 02:27:56 pmWell, considering that they are monitoring all Linux users by default, as confirmed by the recent leaks, I am sure I am under a 24/7 observation for years already.J.

author: hlavac
author_rank: Frequent Contributor
timestamp: August 01, 2014, 04:30:36 pm
content: Thats because Microsoft is monitoring all the Windows users for them already