Sciencemadness Discussion Board

Responsible Chemical Waste Disposal

PrussianBlue - 26-3-2018 at 04:12

Before I seriously begin to do some home experimenting, a major concern I have is the safe and environmentally responsible disposal of chemical waste. At this point, I do not plan on using any chemicals that I cannot obtain from OTC products (thinners, pool chemicals, etc.). Will my local hazardous waste facility be my best bet?

Their accepted waste list includes:

Paints
Stains
Varnishes
Solvents
Garden pesticides
Flammable products
Poisons
Adhesives
Aerosol cans
Lawn care products
Cleaners
Automotive chemicals

I want to take safe waste disposal quite seriously, so any added insight will be greatly appreciated.

woelen - 26-3-2018 at 04:30

I myself do the following:
- Evaporate organic solvents in air, outside, or burn them away, outside.
- Solutions of toxic metal salts I put in a bottle. I label this bottle with text, telling that it contains heavy metals in solution (the chemical symbol of each of the metals in the solution I put between parentheses in smaller script), and when I bring it to our local hazardous waste facility I tell them it is waste from my photography dark room. Never any questions asked, and still safely brought away with right label. I bring at most a few liters, do not bring big jerry cans full of waste!
- Common inorganic acids I flush away with a lot of water.
- Common strong bases I flush away with a lot of water.
- Solutions of alkali metals, earth alkali metals, B, Al, Fe, Cr(III), Si, Ge, Mn, Sn, Bi and Ti I also flush with a lot of water.
- Cr(VI) I reduce with dil. HCl and Na2SO3 and then flush away.
- Most inorganic simple anions can be flushed away (if the counter ion is not a toxic heavy metal). There are a few which I do not flush away: selenium-based, tellurium-based, arsenic-based, antimony-based, lead-based, most transition-metal anions, such as vanadates, molybdates.

I work in micro quantities (test tubes). In that way, the amount of waste is very small and that's why I feel no issue with flushing a few tens of mg or maybe 100 mg of e.g. Cr(3+) or Mn-salts away. The really toxic stuff, however, I keep.

CobaltChloride - 26-3-2018 at 04:56

A few basic rules I adhere to when dealing with inorganic waste:
1) If your waste only contains alkaline, alkaline-earth metals (besides barium), aluminium and non-toxic anions (Cl, Br, I, SO4, SO3 etc.), it can be safely disposed down the drain. You can also dispose of small quantities (a few grams or so) of iron and chromium III this way.

2) If your waste has a toxic cation and a non-toxic anion, see if there is a way of recycling the metal. For example, I collect all my copper waste in a big PET bottle. After it is filled 2/3 of the volume, I add sodium carbonate to precipitate the copper. This also applies to Mn, Fe, Co, Ni, Zn, Ba and other metals. The carbonate can be heated together with crushed coke or charcoal to recover the metal (besides BaCO3).
For silver you can just add table salt and thus recover the valuable silver.
For lead I can't really say for sure what you should do as I haven't used it yet, but I think you could add some sort of sulfate and then recover the PbSO4. I'm not sure if the remaining liquid contains enough lead to be an environmental threat, so you'd better ask someone else.
I haven't dealt with tin yet so I can't say what you should do with that.
For mercury there are multiple procedures online (see Cody'sLab video and NileRed's video)

3) If your waste has a benign cation but a dangerous anion, try to see if there's any way to neutralize the anion in any way. For example, cyanides react with hypochlorites to make harmless products. Also, chromates and dichromates react with reducing agents (thiosulfates, sulfites, metabisulfites etc.) to make much less dangerous chromium III.

4) If you're dealing with a nonmetal/ metalloid in elemental form or as molecular compounds, research how to deal with it yourself as the people at the hazardous waste facility are not equipped to deal with them and all nonmetals/metalloids are treated differently. There are some completely harmless ones, like silicon and carbon, but there's also some dangerous ones, like sulfur, selenium, arsenic and antimony.

5) If your waste is strongly alkaline or acidic, you can pour it down the drain in small quantities. If there's a lot of waste, you'd need to at least partially neutralize it.

A few rules I adhere to when dealing with organic waste:
1) Collect all solvents in separate containers, label them and bring them to the local hazardous waste facility

2) If your waste only has non-toxic carboxylic acids (formic, acetic, citric, oxalic and others) and their salts of non-toxic cations (the ones mention in the first point in the inorganic category), you can dispose of it down the drain

3) Disposal of all other organic waste has to be researched before the experiment to see if it is possible to safely do it. If it's not doable by an amateur, then I don't attempt the reaction.

If I'm wrong on any of these, please inform me as I don't want to be unknowingly destroying the environment.

[Edited on 26-3-2018 by CobaltChloride]

PrussianBlue - 26-3-2018 at 05:04

I've been informed (but have not confirmed) that the EPA prohibits the open evaporation of any non-aqueous liquid waste in the US. I don't plan on using any heavy metals, highly toxic substances, etc., so I'm not too worried about the disposal of those. My primary concern is the disposal of halogenated organic waste as this will likely come up in the near future. My thoughts are that since some OTC solvents are halogenated organics (e.g. DCM), the hazardous waste facility can likely properly dispose of them.

woelen - 26-3-2018 at 05:16

Evaporation of liters of organic waste is not good, but if you produce e.g. 10 ml of DCM waste, then I would not worry about that and simply evaporate it outside.

With all these things you must put your waste in perspective. If your neighbour is stripping the paint from his wood panels and uses a liter of paint stripper, based on DCM, and you use a few tens of ml of DCM in chemical experiments, then you can draw your own conclusion. The laws you mention are not about tens of ml, not even about liters, otherwise no one could use the product in a home/hobby setting. These laws are for tonnes of chemical waste, produced by factories/big companies on an annual basis.

I work with something like a toxicity-volume product. If I have very toxic waste (e.g. mercury salts, thallium), then I have near-zero emission to the sewer system or into the air (just a granule, the size of a table salt granule may get into the sewer, but not much more), if the waste is not that toxic (e.g. DCM), then a few tens of ml for my few experiments with it on a yearly basis is no issue for me.

Of course, if you use 50 ml of e.g. DCM every day, then things become another matter, but I expect you to use a certain chemical only once or twice for an experiment and then you do not use it for a long time.

Ubya - 26-3-2018 at 08:18

Quote: Originally posted by woelen  
Evaporation of liters of organic waste is not good, but if you produce e.g. 10 ml of DCM waste, then I would not worry about that and simply evaporate it outside.

With all these things you must put your waste in perspective. If your neighbour is stripping the paint from his wood panels and uses a liter of paint stripper, based on DCM, and you use a few tens of ml of DCM in chemical experiments, then you can draw your own conclusion. The laws you mention are not about tens of ml, not even about liters, otherwise no one could use the product in a home/hobby setting. These laws are for tonnes of chemical waste, produced by factories/big companies on an annual basis.

Of course, if you use 50 ml of e.g. DCM every day, then things become another matter, but I expect you to use a certain chemical only once or twice for an experiment and then you do not use it for a long time.


evaporating 10ml of DCM once in a while outside won't do much of a harm, you are right, but also 1 can of freon won't harm anyone once in a while, i know this is an exaggerated example but if everybody thinks like this we would have a worse enviroment. if you make 10ml of solvent waste just keep it until you got a reasonable amount to dispose, it's the best enviromental solution

aga - 26-3-2018 at 11:19

It's pretty much the same no matter what you're doing: don't make a lot of mess/waste to deal with after the fun is over.

My one big gaff (so far) was getting all excited about gold recovery.

Still processing the gallons of waste that got made needlessly - takes all the fun out of it.

BromicAcid - 27-3-2018 at 03:44

I worked in the hazardous waste industry for some time so I could go into detail about what should be done and how you could accomplish it.

That being said, they do a yearly 'clean sweep' event in my city where you can bring in whatever chemicals you want to dispose of. I do oil painting and I usually bring in several jars just labeled flammable. They never ask what they are (mineral spirit, turpentine, etc) they just take them away. I usually point out that it contains cadmium, chromium, etc., but they don't bat an eye. I also bring in containers of paper towels, again containing cadmium, chromium, and other metals from the pigments and they take those away as well. My point being that they usually don't have any questions because most people don't have answers, if they have an event like this in your area you can probably take advantage of it. When my mother-in-law passed away I had plenty of random chemicals that were not identified. Things like pool chlorinator (I would guess by the smell) in a random plastic bottle and they took those as well. Use sane judgment but at least for flammables and metal waste it might be a viable disposal method.

MrHomeScientist - 30-3-2018 at 07:32

Something that would be interesting and enlightening is to research how the official disposal companies deal with various wastes. As a potentially bad example: If they simply incinerate everything, then you're fine doing the same.

BromicAcid, if you have some documentation you could point us to I'd love to read it! This is a very important topic for amateur chemists.

[Edited on 3-30-2018 by MrHomeScientist]

RawWork - 30-3-2018 at 07:51

This topic is not only chemistry problem, but general problem. Disposal of any waste. Bio, nuclear, electronic, natural, animal, whatever we call it. I would not call it disposal but management. Energy or mass is never destroyed or produced. Being able to live with a plan, knowing how to manage everything in advance, first for yourself, than for whole world.

Good starting point is wikipedia, i always start learning from templates:
https://en.wikipedia.org/wiki/Template:Waste
https://en.wikipedia.org/wiki/Template:Environmental_technol...
https://en.wikipedia.org/wiki/Template:Wastewater

[Edited on 30-3-2018 by RawWork]

officescape - 29-4-2018 at 19:12

Could be a possible business opportunity?
Create/buy a high temperature industrial furnace
Offer small-scale/one-off disposal services
Profit!

Most of the disposal companies I have worked with are not interested in one-offs or small scale but there is an obvious need as small companies and hobbyists don't have rotovaps or want to keep buckets of waste around to be picked up by a disposal company.

Now that I think of it, how do most modern disposal companies tend to do it? I imagine furnaces don't scale up well but neither does solvent evaporation.

JJay - 5-8-2018 at 21:57

What is the best way to dispose of barium waste? Neutralize with sulfuric acid and dispose of as a poison?

Deathunter88 - 6-8-2018 at 00:15

Quote: Originally posted by JJay  
What is the best way to dispose of barium waste? Neutralize with sulfuric acid and dispose of as a poison?


Once it's in the form of barium sulfate, there really is no need to treat it as a poison anymore.

JJay - 6-8-2018 at 00:32

That seems reasonable. Barium sulfate is so inert that you could probably grow vegetables in it (not that I'd suggest it).

MrHomeScientist - 6-8-2018 at 12:15

They even let you drink it! To take x-rays of your digestive system; called a 'barium meal.' I had to do that once. Very chalky tasting.

Heptylene - 6-8-2018 at 12:46

Personally I have four containers for the waste I produce:
1) Toxic heavy metals liquid waste, that is everything except Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti and Fe. And I recycle copper, silver, and the other very expensive metals. I haven't decided what to do with this, but storing it is not a problem for now.
2) Non-halogenated organic solvents, with only minute traces of halogenated compounds. This I will likely burn at some point.
3) Halogenated organic solvents, which consists of only DCM at the moment, and which I will recycle when I have enough of it.
4) Organic aqueous waste. This will be evaporated to a solid and thrown in the trash as incinerable waste.

Acids and bases I just dump down the drain. After all sulfuric acid and sodium hydroxide are used as drain cleaner...

DavidJR - 6-8-2018 at 14:28

Quote: Originally posted by MrHomeScientist  
They even let you drink it! To take x-rays of your digestive system; called a 'barium meal.' I had to do that once. Very chalky tasting.


They also do the same thing up the other end...

Abromination - 8-8-2018 at 17:04

How concerned should I be about the toxicity of copper salts? I have about 5 liters of waste in storage dedicated to compatible copper salts. Also, due to mild toxicity of lithium salts, can those just be flushed down the sink? I ask about the copper salts because I would like to know if I should bring it into
hazardous waste or just get rid of it otherwise.

CobaltChloride - 8-8-2018 at 17:12

In my opinion, the best course of action is adding sodium carbonate (be careful; it will foam a lot) or sodium hydroxide to the copper waste until the pH is basic and then pouring the liquid down the drain and saving the solid precipitate of copper hydroxide (in the case of NaOH) or basic copper carbonate (in the case of Na2CO3).

mayko - 8-8-2018 at 20:28

I reclaim my copper waste by precipitation of the metal with scrap iron, then add baking soda to the iron solution to get iron oxide.

Heptylene - 14-8-2018 at 16:02

@Abromination: You might want to add NaOH to your copper salts (provided there is enough of them to make recovery worthwile) and boil the solution. This will yield a precipitate of copper(II) hydroxide which decomposes immediately into copper(II) oxide in boiling water. This can then be filtered or decanted and used to make other copper salts by reaction with the appropriate acid. Copper oxide is very handy because you don't need to oxidize the copper again, such that reaction with e.g. sulfuric acid will be immediate.

The waste solution should be harmless after this treatment considering the low solubility of copper hydroxide and oxide, and assuming there isn't anything else in it besides copper salts.

Lithium I don't think is toxic enough to warrant a specific treatment unless you have hundreds of grams of it.

fusso - 14-8-2018 at 21:38

Why throw away the common metal waste(all metals other than Na Mg Al K Ca Fe. Even Zn is worth saving as you may not obtain old batteries as fast as you use Zn)? I think they're worth saving and turned into useful compounds after saving like 100g of them.

Abromination - 16-8-2018 at 21:52

How can ammonia waste be disposed of? I have a large amount from making tetraamminediaquacopper dihydroxide and want to know what to do with it before pouring it down the drain.

JJay - 16-8-2018 at 22:04

Ammonia solutions can be put down the drain.

Mush - 20-8-2018 at 12:51

Quote: Originally posted by Abromination  
How can ammonia waste be disposed of? I have a large amount from making tetraamminediaquacopper dihydroxide and want to know what to do with it before pouring it down the drain.


Neutralise with acid first (carefully with any acid), then it can go to the drain. You don't want pissed off neighbours knonking on your door due to NH3 gas in drainage system.

JJay - 20-8-2018 at 13:05

What?? That's ridiculous. Do you know how much ammonia goes down the drain?

Mush - 20-8-2018 at 13:12

Bear in mind guys in most developed countries sewage-water recycling facilities do test their water in both ends. So , it ain't too wise flushing heavy metals down in the toilet. In many cases they can /want to identify the source.

Local hazardous waste facility is the best bet.

If the solution is water based just let the water evaporate until you have cc. solution of heavy metals or just the salts themselfs , dispose them as paint leftover in a can .

It won't be cheap also involves some paper work in most case . This way one can make sure his/her waste is managed properly. If one wants anonymus solution for waste management has to find other ways.

mayko - 20-8-2018 at 13:47

The ScienceMadness Wiki has a page covering this topic:

http://www.sciencemadness.org/smwiki/index.php/Proper_dispos...

JJay - 20-8-2018 at 14:09

After reviewing the wiki page, my advice is this:

If you are disposing of anhydrous ammonia as an amateur, follow the wiki's suggestions on how to dispose of it. Do not pour anhydrous ammonia down the drain.

If you are disposing of anhydrous ammonia in quantities that are subject to the Emergency Planning and Community Right-to-Know Act, follow the local site plan.

If you are an amateur and disposing of reasonable quantities of ammonia solutions in concentrations of less than 30%, feel free to pour them down the drain.

Oh and copper salts really aren't supposed to be poured down the drain.