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Disposal of unused muriatic (hydrochloric) acid


Q. I do have a background in metal fabrication, but I have a small stock of muriatic acidamazoninfo from concrete work in trade. The local landfill resists receiving hazardous elements except on a certain date, per year. I want to rid myself of this before locating back to Maine, where I last had use of it. My speculative need of it in the future is too lame to justify keeping the hazard in store. This is uncontaminated product. Is there a simple way to reduce it to a neutral condition? I appreciate your consideration and reply.

James William Rayne
hobbyist - Newark, Delaware, USA


A. Hi James,

Seeing that no Guru had replied, how about having a gander in the archives at # 12044. Surely there are some useful hints there ... even more if you are (heaven forbid) a dog lover.

freeman newton portrait Freeman Newton
- White Rock, British Columbia, Canada
freeman newton died


A. James, when I want to get rid of hydrochloric acid, I mix it with sodium hydroxide (NaOH) a.k.a caustic soda, until it is neutralized. HCl + NaOH gives NaCl and water.

Geez, I hope I don't have to emphasize that you should be careful, and to make sure that it's completely neutral (pH 7). I presume you know the strength of the muriatic acid, so it should be simple to calculate the amount of caustic soda you need. If you've any doubt, bring a pizza into your local high school chemistry class and let them calculate it for you.

Good luck! And remember, no one at finishing dot com advocates non-adherence to environmental laws!

Lee Gearhart
East Aurora, New York


A. Hi there,

As above but caustic soda is a little too violent in the reaction and some what expensive. Try some Calcium Hydroxide I think its also sold in the plastering trade as slaked lime, its an alkaline, dilute your acid and in a large 200 Liter plastic drum feed the calcium hydroxide (Slowly) Stir and check using litmus paper to gauge when when its neutralized, This time you end up with Calcium Chloride. and water.

Robert Fyfe
Audio Eng. - Wyoming, NSW, Australia


thumbsup2Thank you, Lee, yes, I'll hold to my best on the environment. Pizza's great, and I throw the dough, so maybe that's an angle. Bill (James William) Rayne. Freeman, I'm replying with thanks prior to following your directions back into archives. The car looks great! Robert, you've given me the journeyman's answer, and you nailed my back-off (some experience) from caustic soda. I can get the stuff and already have a drum. If you know (or anybody) whether the resulting calcium chloride is ALSO a problem, please reply.

Thank you, all!

James William Rayne
hobby/home improvements - Newark, Delaware, USA


A. I recall that the company I retired from a while back had about 1000 gallons of conc. sulfuric leak into a concrete containment pit. A local environmental services company came in and removed it for shipment to an "acid reclaimer" I believe somewhere there, in Delaware area, possibly at Dupont? We would use soda ash routinely to neutralize small drips of either sulfuric or nitric acid, by the way. Fumes were bad, but tolerable, when ventilation was adequate.

W. Carl Erickson
- Vernon, New York


A. Dear James,

Calcium Chloride, like many Calcium Salts are insoluble in water. Our bones for example are mainly Calcium Phosphate. In the reaction converting your unwanted Hydrochloric Acid to Calcium Chloride, dilute the acid first otherwise it may splutter, remember that they use Hydrochloric, or when tainted with Iron, then sold as muriatic for cleaning cement off new brickwork, the product is Calcium Chloride and lesser amounts of other things (Silicates) and on construction sites doesn't this normally flow straight down the drain or into ground water. Check with your local E.P.A on acceptable disposal methods. Then again if you dried out the Calcium Chloride (Anhydrous) it makes a great dessicant (Water Absorber) but it is an Irritant...When its this dry...gets up your nose, arh-choo.

Robert Fyfe
Audio Eng. - Gosford, NSW, Australia

April 13, 2011

A. If this acid is new, uncontaminated then why destroy it? Maybe you can find someone who can use it? There is a group of Yahoo mailing lists called FreeCycle where people go to give things away they don't want but might still be useful. Or there's CraigsList. I've gotten rid of quite a few things that way. It's nice when somebody shows up, takes the unwanted item away in THEIR car at YOUR convenience and is even grateful to do so!

I came across your post looking for information about using Muriatic acid for PCB etching. I live too far away to consider taking it but for that use I think just about any Hackerspace would love to have it and be very appreciative. I checked the Hackerspace wiki though and the only one I found for Newark was a group of people interested in starting one. You could try contacting them but their website and twitter links don't actually work so I don't know if their email contact is any better or not. I don't know what other cities are near Newark to check them too.

Good luck!

Leif Burrow
- Toledo, Ohio, USA

September 6, 2012

A. Muriatic acid is used in many, many applications. If I were in your area, I would take the stuff from you for nothing.........then I would put it into my swimming pool as I do on an almost weekly basis for PH adjustment.

Find a neighbor or pool company and offer it to them. I use about three gallons/month. Ironically, I also purchase about 2,500 gallons a month at my job, which becomes contaminated and has to be disposed of properly.

Hope this answer came soon enough.

David Jaye
- Houston, Texas, USA

July 12, 2012

Q. I am a student and I have a project on Disposal of Calcium Chloride.
What are the industrial ways to dispose the waste calcium chloride.

Narendra deleted
student - Gujarat, India

September 10, 2012

A. Neandra, I have no idea if this is legal in your country. but you can mix it into concrete and make stepping stones out of it. Mixing it into epoxy is an alternative, but it costs a lot more.

James Watts
- Navarre, Florida
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