This is how I worked out my neutralization procedure:
You have heavy metal (probably mostly copper) nitrates in solution
Depending on what you dissolved, you could have many metals in solution, if you only dissolve pure copper in nitric acid then yes you would only have a copper nitrate solution, but I doubt your only dissolving pure copper here, but possibly many metals in your solution probably many you have never heard of, and I do not think nitric was the only acid or chemical you used (at least your statements below do not reflect that.
Add iron, you get iron nitrate and heavy metal
This would be somewhat true if only copper in the solution, and you were able to cement out all of the copper from solution, Iron will not replace the other metals higher than copper in the reactivity series, did you have any of these in solution? And was this only a nitrate solution or were other acids or chemicals added, these toxic soups get very complicated in chemistry mixing more than one acid and one metal.
Lye is sodium hydroxide, when mixed with iron nitrate you get iron hydroxide and sodium nitrate
if there is excess HCl, this will also react with lye to form sodium chloride (table salt)
Here your stating you also had chlorides in solution this changes the whole picture of your above statement, what other chemicals are in solution (sulfates), and more? Now what other metals? I do not think just copper, electronic scrap contains many metals, these dissolved in the acids you have used made a toxic soup, although we can treat them to make them safer to dispose of properly. Properly is the key word here.
We will not make them harmless, some of these dangerous metals would still be in the solution after your treatments, now since you also have chloride metal salts in solution, and nitrate salts in solution mixed with metals (yes you removed many of the metals but not all of them so this solution would not just be sodium nitrate, or just sodium chloride but would be a base metals salts of sodium nitrates and chlorides sulfates and any other chemical you mixed, definitely not something I would want in my food chain or my well water, or a child playing in the damp grass where you poured this toxic solution.
When enough lye has been added to neutralize the entire iron nitrate, the pH will increase. When it's around pH 7, you're done.
Actually you would need to get it more basic and then bring the pH back down, even then some metals are soluble in water, especially salt waters of metal nitrates chlorides and sulfates, many metals are also soluble as hydroxides, so at any stage here you would be dumping these metals, the water would evaporate, seep down into the water table or flow off with surface water to the river someone drinks from, carrying these metals and salts of acids with it, and possibly leaching other toxins in the soil and ore they pass through, before reaching the water table.
In water, iron hydroxide will eventually turn into iron oxide (rust).
Actually iron is soluble in water, my well water is high in iron content, it is safe to drink and healthy, but that would not be the case if you dumped your toxic waste in an area were my water leaches through the soil before it gets to my pump.
Iron hydroxide and iron oxide will slowly sink to the bottom and you can decant off the liquid, which contains sodium nitrate
Iron hydroxide and iron oxide are safe to throw in the trash
If all you had was sodium nitrate why not reuse it to make nitric acid or for some other use you needed nitrates for like poor mans aqua regia, But I suspect your waste contains much more than sodium nitrate.
Sodium nitrate is hazardous to environment in huge quantities (it's a major component of fertilizer that environmentalists complain about after floods and huge farming and fertilizer being washed into the ocean), but not bad in small quantities (even helpful to plants?). Can be poured down drain (Can it be used in your garden?)
Would you want to eat from a garden some refiner poured his toxic waste into? Even if he thought it was safe? I would not.
Sodium carbonate/bicarbonate can be used in place of sodium hydroxide, but it will produce iron carbonate (Siderite) instead of rust. Still safe to toss into the trash, just a different substance.
This is how I worked out my neutralization procedure:
If dried and disposed of in the trash where it is taken to a landfill, it would be legal. And fairly safe as long as the dump and landfill kept the runoff and water leach from our water table.
Mystic, I think you have oversimplified this in your mind, with that thinking you can harm yourself or others, these metals we put into solution are toxic, your waste is toxic, even after you add other metals and bases or caustics to them, please read dealing with waste in the safety section, it explains the best way we know of to treat these waste and dispose of them legally and as safely as possible, doing this can help to protect you and others.
What happens when you get a visit from the EPA, and department of environmental quality, and they see the big patch of dead vegetation where you dumped the solution from your lab you figured was safe, and they sent it to a lab to be tested for toxins, do you think they could follow your chemistry and explanation of what you did, and would not fine you or worse?
Heck they may have no idea of chemistry, they could see you dump distilled water from your lab and not know the difference, to them it came from your lab it is pollution. And you polluted the environment, because of what we do we need to educate ourselves and be very cautious of what we do with these chemicals and waste products.
Your fun little hobby would not be fun anymore after the DEQ were done testing your soil.
but Isn't it just sodium nitrate dissolve in water? And isn't sodium nitrate one of the major fertilizer components?
That's the only reasoning I have. If you guys have better knowledge to the contrary, I'd go with that.
Nope, I do not think it is just sodium nitrate dissolved in water, and if I did I would not dump it, I would reuse it.
read dealing with waste (flagged in the safety section of the forum) and go with that.
