# Neutralizing Gases



## banjags (Feb 8, 2008)

I am not a chemist by any stretch of the imagination. So I ask you guys. I like in a city so I do not want billowing clouds of fumes coming from my shed.
What would I bubble the reaction gases thru to neutralize them?

Dilute Nitric Acid?
AR?
HCL and Peroxide?
HCL and bleach?

From what I gather it would be a solution of water and baking soda?

I am just finishing up collecting and building my apparatus for my very first refining session.


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## lazersteve (Feb 8, 2008)

Banjags,

The best solution of course is a packed tower (or series of towers) or optimally a good fume hood. 

In a pinch you can work with AP and HCl-Cl outdoors with only minor fuming as compared to the fumes of AR and Nitric reactions. The fumes from AP are produced mainly when it is mixed and only very slowly thereafter. These slowly evolved fumes are rough on nearby metal objects.

HCl-Cl fumes can be kept to a minimum by carefully controlling the addition rate of the Clorox. If you are getting large clouds of choking green gas (chlorine), then you should cut back on the amount of Clorox you are adding in a single dose. Add the Clorox slowly and only as much as is need to dissolve the gold foils or powder. You will only notice the odor of chlorine when done properly in an outdoor or well ventilated area. Practice using smaller amounts of HCl-Cl until you get the hang of it and learn what to look for. 

Steve


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## banjags (Feb 9, 2008)

by a packed tower i assume your are referring to those long tubes filled with some kind of liquid that they bubble the reaction fumes thru. What is it that that bubble the fumes thru?
Could a person use a thick piece of cloth or several soaked in a solution to help cut down on the fumes?


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## lazersteve (Feb 9, 2008)

A packed tower consists of a long tube, or series of tubes, filled with high surface area chemical resistant items. This packing is typically made of PVC or other Acid resistant materials and allows the vapors to come into contact with the basic solution which is sprayed down from the top of the tower in a mist.

A suitable pump keeps the basic liquid circulating back to the top of the tower. As the basic solution absorbs the fumes it forms a salt solution. This solution should be changed when it's pH reaches 7 (neutral). 

Steve


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## aflacglobal (Feb 9, 2008)

A good example would be the surface area of the beads in a catalytic converter. More surface area Means more dispersion.


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## Absolutsecurity (Feb 10, 2008)

Couldnt you also refract or condense your gases like a condensing column and capture what went up as a gas back to a liquid form???????????

Just a thought!

Glynn


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## Noxx (Feb 10, 2008)

You can condense certain gases but not all of them.

NO2 cannot be condensed with regular water cooled condensers.


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## skyline27 (Feb 10, 2008)

How do you dispose of the liquid from the stack? What is it's composition?


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## Lou (Feb 10, 2008)

It would likely be a salt solution of nitrates and chlorides. It could likely be dumped out on the ground.


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## Irons (Feb 10, 2008)

If you have a an absorbtion tower for NO2, you can produce Sodium Nitrate as a byproduct. Add some Hydrogen peroxide or Sodium Percarbonate (OxyClean) to the Sodium Hydroxide spray to minimize the production of Sodium Nitrite. You can then reuse the Sodium Nitrate to make more Nitric Acid.
Another tower can be used to Absorb Chlorine from the HCl/Cl process to produce Sodium Hypochlorite which can be recycled back into the process.

Hook up your reaction vessel to the appropriate tower depending on what process you are using to digest your PMs.

Doing this can almost eliminate gaseous pollution emissions and recover valuable chemicals for reuse.


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## Platdigger (Feb 10, 2008)

How would "you" set up one of these spray towers Irons?
BTW, great ideas!
Randy


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## Irons (Feb 10, 2008)

Platdigger said:


> How would "you" set up one of these spray towers Irons?
> BTW, great ideas!
> Randy



I have loads of HDPE milk jugs that I plan to cut up and form into filler for the tower. CPVC Chlorinated Poly Vinyl Chloride seems like a logical choice for the tower itself.. My idea is to create the most surface area without obstructing the flow. I had considered bubbling the gasses into a cylinder full of NaOH solution but it would create an undesirable back pressure.
I will have to scale up considerably to generate enough effluent to get any reasonable test results.
It's a project for this Summer. Right now, it's too cold to do any work.

For the time being, I have been using crushed marble to absorb gasses and it works well but I would like to be able to recycle and have zero emissions.

It's not just a matter of saving money, it's the right thing to do.


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## lazersteve (Feb 10, 2008)

Like Irons, I too have been designing a set of packed towers for NOx and Cl fume control. Fortunately the weather is nice here in Florida and I can work on it in my 'free' time.

My towers will be packed with pond bio filter gizmos that are made for maximum surface area in the pond filtration system.

[img:527:537]http://www.goldrecovery.us/images/bioring.jpg[/img]

Lowes sells this material in the garden center. I'm tinkering with the idea of several shorter columns where each one feeds the next. 

Steve


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## Irons (Feb 10, 2008)

I'll have to check out Lowes. 
I have a pile of jugs that I need to find a use for, that's why I chose that route, otherwise the prefab filler is probably the logical choice. We'll have to compare notes.

It would be good to have a chart to let people figure out how big a tower they will need for a given volume of material being digested, that way people can build one that will suit their needs without over-engineering it.


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## Gotrek (Feb 11, 2008)

lazersteve said:


> My towers will be packed with pond bio filter gizmos that are made for maximum surface area in the pond filtration system.
> 
> 
> Steve




Bio balls? 
[img:332:308]http://www.wonbrothers.com/images/bio%20ball.gif[/img]


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## lazersteve (Feb 11, 2008)

Gortek,

Exactly.

The ones that came with my pond filter system are shown in the photo.

Steve


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## Gotrek (Feb 11, 2008)

lazersteve said:


> Gortek,
> 
> Exactly.
> 
> ...



I have a few buckets of the ones I've posted. I've opted to use more readily available items in my filters (for my fish tanks not fume filters).


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## SilverNitrate (Feb 12, 2008)

scrubbing your fumes can be done easily. in a make-shift lab any acid gases can be bubbled thru a column of water, baking soda, and if more advanced along with ammonia. I uses a suction on the end so all the bad-gases are sucked in from the source, bubbled thru neutralizer, then into baking soda, (making sure no moisture enter the compressor) a very very slight ammonia smell lets me know all the acid gases are neutral.


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## banjags (Feb 13, 2008)

SilverNitrate said:


> scrubbing your fumes can be done easily. in a make-shift lab any acid gases can be bubbled thru a column of water, baking soda, and if more advanced along with ammonia. I uses a suction on the end so all the bad-gases are sucked in from the source, bubbled thru neutralizer, then into baking soda, (making sure no moisture enter the compressor) a very very slight ammonia smell lets me know all the acid gases are neutral.



This is kinda what I am looking to do. Do you make a water baking soda solution ? Or water ammonia solution. I have an idea in my head for the bubbling tubes but not sure what to use in them. Do you have any pictures of you setup


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## SilverNitrate (Feb 14, 2008)

Sorry, don't have any pix. (though I may draw a pic as example)
Your bubbling sollution can be a mixture of baking soda and ammonia.
I actually use hydroxide and ammonia mixture. 

The suction that moves the gases can be an old hospital pump or old portable nebulizer.


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## OMG (Feb 15, 2008)

I read in wiki about titanium dioxide and how it its used in special concrete blocks to convert NOx gases to nitrates. Check it out. That might interest someone.


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## skyline27 (Feb 15, 2008)

This is a really interesting thread. I've been wondering about this topic for some time.

What is the proper way to dispose of the liquid used to filter the gases?


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## 61 silverman (May 1, 2008)

Hi, everyone new and old, I just bought HOKE's book read the first 130 pages, Hoke say's one way too contain your fumes is too place a plastic or glass dish about 2 inches deep. Put 1 inch or so of water in the dish, place your container material will be disolved in, in the dish,take another container LARGE ENOUGH too cover disolving dish -YET will set inside the dish containing the water, Placing this container over the reaction vessel and in the water the fumes are trapped in the water which can be neutralized and disposed of.


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## Palladium (May 1, 2008)

Welcome back Mark. :wink:


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