Disposal of Etchant!

SABorn, the problem is I already DID post an extensive description on how to handle metal bearing solutions over 2 years ago, no one bothered to search for it and for some REALLY strange reason people think I don't know what I'm talking about =) This information is public knowledge from multiple websites if you spend the 10 minutes to search for it.

I never knew about the steel helping precipitate copper out of the solution though, I'll have to remember that.

https://www.electro-tech-online.com/threads/calling-on-all-chemists.98615/

If you want to get a little more metal out of the water look up the exact PH and temperature the solution should be brought to to optimize precipitation for that metal.

**broken link removed**

**broken link removed** is one viable method to help with the precipitation process. Chemical polymers are often used to increase the floc size and aid in precipitation but I can't think of a viable hobbyist coagulation aid, I'm no chemist but I know the practicalities of this because I worked at a plating shop for 10 years. Ferric chloride itself is actually used as a coagulation aid as it makes lighter flocs that form heavier, so it's quiet easy to treat.

Sceadwian said:

Regardless it's not okay to dispose of this down the drain ANYWHERE EVER. If there are no faclities, just hang on to it! A lifetimes usage of etchant and hazardous chemicals for a common household would take up a few plastic gallon jugs.....

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I know there are people here from around the world but..

In the US some governments (city or county that I have seen) hold waste disposal events. If you can pass it off to them. Perhaps other places are doing the same.

Even if there aren't, simply trying to contact people in industry in the area will be able to give you leads on companies that have conscience enough to allow the public to add such a trivial amount of waste to their treatment streams. You do live in a locality that might make it difficult but the effort is worth, DIY waste treatment is at best a stop gap measure for having it disposed of properly.

I understand your concern and from a industry point of view yes very important.

But from a realistic point of view it is really not worth the argument for the hobbiest.

Lets face it, one in 500 members here might buy 1 litre of ferric chloride every 5-10 years and if they dumped it down the drain it would not even come close to the minor spills industry has daily.

The enviromental damage done driving the car to a waste disposal centre is more likely greater than the chemical pollution.

Look at all the nasty crap on the market for cleaning the bathroom that goes down the drain daily from 1000's of households.

There is a fine line between beating a drum on a high horse and being realistic.

Pete.

SABorn said:

The solution is not much more than hydrochloric acid now and can be neutralized with some caustic solution or even bleach, bicarb soda, baking soda, etc.

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I wouldn't mix bleach and hydrochloric acid together if you value your lungs, chlorine gas does not play well with lung tissue.

Mike.

Good point Mike, i would normally dump a handfull of lime or cement powder in it, but didnt figure everyone would have that.

Hell you could even just use soil to some degree. HCL is not what i would call a bad acid as far as most acids go.

Pete.

SABorn, the lackadaisical attitude about this problem is what is ACTUALLY the problem, I'll respond in full after I get a reply back on a few e-mails. This isn't some high horse I'm trying to ride here, this is plain simple common sense. If something is bad you don't do it, a little bad is just as bad as a big bad because so many people think that way, all those little bads equal a big bad in the end because of the number of people that think it's okay.

If you don't think it's applicable to the hobbyist community then I'd love for you to come up with some real numbers, how many hobbyists in, say the US use chemicals like ferric chloride and and others and just dump it down the drain? The problem is there is almost no way to come up with those numbers because there's no system in place to monitor it, so you only THINK that there is no problem because there are no in your face values to point to.

I'll see what I can do about getting some proper information on this matter to prove the point, but I will not let this lay as it stands, that type of attitude is a crime against common sense.

As far as 'bad acid' vs 'good acid' that's a very non-sensicle arugement. It's not the type of material, it's the concentration, and overall amount, where it's disposed of and how it will concentrate at the disposal site, not to mention what it'll do along the way. You're very much simply ignoring the complexity of the issue and writing it off.

Depending on the quantity almost anything can be just thrown away. Especially when you consider the steps most waste disposal plants take in order to divide out the unwanted waste.

Let's do some maths.

In my building there are 120 apartments with an average of 2.4 persons per apartment. Each person poos 2mg (rdi) of copper per day. So, communally, we dump 576mg per day or 210g per year of copper down the toilet. One square inch of PCB contains 200mg per square inch. I typically etch about 3 boards per year at around 4sqin per board so I dump an additional 2.4g down the drain.

I've not even mentioned the fact that the water comes (and goes) in copper pipes or the unfortunate people with the copper bracelets for arthritis who wash the verdigris off each day or copper pans or ....

Unless you are doing large amounts, which is really silly as a manufacturer will be much cheaper, it's not a problem.

As I mentioned earlier, I use Ammonium Persulphate as I know it is safe to dump down the toilet when spent. If anyone's wondering about the Ammonia, just smell a babies nappy (diaper) to see how much of that we dump each day.

Lastly, if anyone is still unhappy about dumping copper down the toilet, just mix Sodium Bicarbonate with the spent solution*, let it settle, poor off the clear Sodium Sulphate solution down the drain and throw the Copper Carbonate precipitate in the trash. *Lots of foaming so do it slowly.

Mike.

The only math there are the numbers required for self justification, they're scientifically invalid because they have no statistically relevant basis to be derived from.

Pommie you're burning your tires.

Sceadwian said:

The only math there are the numbers required for self justification, they're scientifically invalid because they have no statistically relevant basis to be derived from.

Pommie you're burning your tires.

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Care to point out which numbers are wrong?

Mike.

All of them, lets break it down.

In your building means nothing. It's one building, out of how many in relation to the population of your city?

We don't poop dissolved copper in a strongly acidic solution, anything that ends up going through us wasn't used by us and is in a metal form, and is immobile until it hits a strong acid. Comparing the two shows you do not know what is actually going on.

You've limited your community to the building you're in, not the larger community or city or country, or tried to valuate this to the rest of the world.

Again mentioning copper pipes shows pure ignorance of the matter. We're talking about active dissolved metal in solution, not solid metals in neutral streams.
Lead pipes are still in place in vast populations, and it doesn't matter much until they break and the public goes 'lead pipes? OMG! EVIL!' Solid lead is immobile in a neutral PH environments. How many people do you know that deal with lead based solders have come down with lead poisoning? NONE, because it's not dissolved lead in an body digestible form, it's metallic lead and an alloy and at best by physical contact. The same amount of lead ingested in a soluble form into the body would KILL someone at a tiny fraction of the lead content of a typical solder. Again you do NOT know what you're talking about.

You said unless you're doing large amounts. Large is RELATIVE to the population that is doing it. In this case it's not even known or measurable, except for the fact that what you consider something safe to dump down the drain the US consider es a trade waste (regardless of public or industrial source it is a hazardous waste)

I tried pointing out the fact that a (local) U.S. government agency advocates pouring 2lb of CuSO4 down your drain twice a year.

I tried pointing out the relatively small amount involved using my building as an example.

You know what, you're correct, I don't know what I'm talking about. I'll be quiet now.

Mike.

You did, and we covered that was in locals that have active root infiltration in the sewer systems, aka something to take up the dissolved copper. It's a location specific solution that turns the currently perceived waste stream into a benefit, which DOES NO EXIST in the larger population. The relativly small amount used in your building is totally disregarded unless you can account for every single gram of metal that is in soluble form at the end point of the sewer system that serves EVERY point that also contacts you. Meaning you CAN'T account for this, there is no statistical information. Any value above 0 for burden on the existing system is not good.

Now keep this in mind.

I have provide links and information to basic PH neutralization for most problem metals in a simple basic or acidic solution, assuming there are no chelating agents. Neutralization simply means use an acidic or basic compound to reduce or gain net PH to the required value, mix gently and allow to settle, dump the clear liquid concentrate dry and then immobilize the sludge.