Building my first fume hood and scrubber

[Tylerb752]

Ive been reading 4metals posts and have come up with a plan that id like to run by the experts. Ive read that when using AR that the gas is needed for the reaction. Is that true? Based on this i wanted something that doesnt directly pull all the gas away from the reaction ie: putting the beaker in a sealed bucket. The bucket plan also doesnt allow me to use a hot plate. My plan is to put my beaker on the hot plate, cover the beaker with a beaker cover, then put a funnel over the beaker to pull gas that escapes into the scrubber. Using 2 venturi systems, one for the blower and one on a shutoff valve for the scrubber. What solutions do i need in my scrubbers to nuetrilize the gas? Ive read that in a single scrubber system they use lye raining on plastic peices that the gas is forced through. Do i need the plastic peices in this type of scrubber system. Im sorry for all the questions but like i said this is my first time doing this.

 

[FrugalRefiner]

Ive read that when using AR that the gas is needed for the reaction. Is that true?

The gas isn't "needed" for the reaction. But it is useful if it can be condensed and returned to the reaction. The primary gas is NO_x, a variety of nitrogen/oxygen gasses. These gasses can be converted back into nitric acid, which if returned to the reaction reduces waste and reduces the amount of nitric needed to complete the job.

Dave

 

[rickbb]

Having that watch glass, (beaker cover), will greatly help in reducing the NOX that escapes. A lot of the fumes will condense and drip back down into the digestion beaker, also saving you some nitric.

Most people use a dilute hydrogen peroxide solution and some plastic balls to bubble the fume exhaust through. The balls increase the surface area allowing the hot gas to better condense back to liquid.

You could also use plain cold water with or without balls. If you use distilled water as cold as you can get it the NOX will condense and make the water a dilute nitric acid.

Just depends on the volume of fume exhaust you are going to "scrub". And how efficient you want the scrubbing to be. And if you want to capture the acid to reuse or just neutralize the NOX to clean your exhaust before sending it up in the air, etc.

 

[Tylerb752]

So my setup will work? So first through the diluted peroxide then through lye then distilled water? How diluted should i make the peroxide?

 

[Tylerb752]

And i am only trying to scrub exhaust not reuse

 

[Tylerb752]

On second though it would be helpful to reuse. So distilled water (for reuse) then peroxide then lye? Sorry thinking as i go here. Then i would check ph on water tank and when it hits a certain mark (what mark would that be?) I can siphon it to reuse?

 

[anachronism]

Also don't forget that using H2O2 in your AR will reduce the amount of NOx produced.

 

[Tylerb752]

So reading other posts i have determined that if i use h2o2 first then h2o then lye i will be turning the h2o into hno3. I am not a chemist but does this equation make sense? Also i understand that i can add more lye to the last station to keep it akeline but what do i do with the h2o2? How do i upkeep the first h2o2 station?

 

[philddreamer]

rickbb wrote:

Having that watch glass, (beaker cover), will greatly help in reducing the NOX that escapes. A lot of the fumes will condense and drip back down into the digestion beaker, also saving you some nitric.

That is so true...
I use one, and I also like to place a small kaewool ball at the pouring lip. This makes a "tighter" seal and helps keep more of the NOx fumes in the beaker, which in turn condense and drip back into the solution. You will save nitric!

Also i understand that i can add more lye to the last station to keep it alkaline but what do I do with the H2O2? How do I upkeep the first H2O2 station?

I re-use the solutions from the 1st and 2nd columns when I start a new AR process...

Take care! Phil

 

[francisco rodriguez]

I worked on a filtered cooker hood, so the losses were eventually recovered.
Good morning everyone, could someone explain these harold words to me?

If possible with a photo or drawing.

Thank you very much.


Paco.