NOX Capture method

[Sancho_n_Pedro]

I'm sure I read this in Hoke's book... There is a mention one one chapter on the use of a bell jar and a bowl of distilled water with nitric acid placed into a beaker with the item to be broken down, and then covered by a bell jar. This is so that the gas slowly reacts with the H2O and coverts back into an acid.

Just wondering if this is an approach anyone has tried, as its one I was considering, so that there are no toxic fumes that can escape (even though the process will be carried out outside)?

 

[Yggdrasil]

I'm sure I read this in Hoke's book... There is a mention one one chapter on the use of a bell jar and a bowl of distilled water with nitric acid placed into a beaker with the item to be broken down, and then covered by a bell jar. This is so that the gas slowly reacts with the H2O and coverts back into an acid.

Just wondering if this is an approach anyone has tried, as its one I was considering, so that there are no toxic fumes that can escape (even though the process will be carried out outside)?

It can work to some degree, but it can't handle high volumes of NOx.
You can use Peroxide or NaOH to capture the fumes.
Better use a bottle train with an eductor.

 

[Shark]

It is similar to using a watch glass on a beaker. It will catch and recycle some of the NOx depending on how much is created. I think maybe Lou once mentioned using plastic wrap and a marble to create a type of condenser over a beaker as well. I much prefer proper shaped watch glasses but have used a variety of glassware at times.

 

[eaglekeeper]

If you chose to use NaOH in your system, the nitric wont be recoverable.

 

[Sancho_n_Pedro]

If you chose to use NaOH in your system, the nitric wont be recoverable.

So essentially each time you use Nitric alone to recover PMs, you can potentially recover some of the Nitric acid?

 

[Martijn]

So essentially each time you use Nitric alone to recover PMs, you can potentially recover some of the Nitric acid?

Yes. More than some. Both from the NOX gases as well as from metal nitrate salts.

 

[eaglekeeper]

So essentially each time you use Nitric alone to recover PMs, you can potentially recover some of the Nitric acid?

If you use water or Peroxide you can recover some of the nitric... but I guess that depends on how efficient your system is.

 

[Yggdrasil]

So essentially each time you use Nitric alone to recover PMs, you can potentially recover some of the Nitric acid?

Even from AR, that is why it is efficient to reflux when dissolving your PMs.

 

[Sancho_n_Pedro]

Cool. Will look out for an alternate to buying an expensive bell jar now. Anyone got any suggestions for use? I was going to go with a 2l beaker over a 500ml one for now, but I think the amount of gases produced could cause it to pop (probably why a bell jar is think glass).

 

[eaglekeeper]

Maybe an inverted funnel.

Skip to 3:15.....Could give you some ideas, but I don't know how efficient it is.

 

[Sancho_n_Pedro]

Maybe an inverted funnel.

Skip to 3:15.....Could give you some ideas, but I don't know how efficient it is.

That seems like a great idea. Guess I just need to look for some tubing now, as I have the funnel already.

 

[Martijn]

Cool. Will look out for an alternate to buying an expensive bell jar now. Anyone got any suggestions for use? I was going to go with a 2l beaker over a 500ml one for now, but I think the amount of gases produced could cause it to pop (probably why a bell jar is think glass).

What are you planning to use this for? Making nitric or digesting metal?

 

[Yggdrasil]

Cool. Will look out for an alternate to buying an expensive bell jar now. Anyone got any suggestions for use? I was going to go with a 2l beaker over a 500ml one for now, but I think the amount of gases produced could cause it to pop (probably why a bell jar is think glass).

It is much cheaper and more efficient to use a train of flasks and an e-ductor vacuum pump to draw the solution through.
Or using a plain cover glass for the reaction beaker.
If you use a "closed" reflux system et will work even better.
These will all be better than buying a thick walled bell jar.
Which by the way you do not need, just use a bigger beaker inverted with something to weigh it down.
There should not be pressure inside.

 

[Shark]

Here is one I used for a long time. It is a candle holder sitting in a tall flower vase. (I now only use beakers) for really small jobs it worked pretty well.

 

[Sancho_n_Pedro]

It is much cheaper and more efficient to use a train of flasks and an e-ductor vacuum pump to draw the solution through.
Or using a plain cover glass for the reaction beaker.
If you use a "closed" reflux system et will work even better.
These will all be better than buying a thick walled bell jar.
Which by the way you do not need, just use a bigger beaker inverted with something to weigh it down.
There should not be pressure inside.

I'm not familiar with the flasks and e-ductor pump method, and was going simple to start with. A beaker weighted down does seem like a method I was going to go with but thought that as the glassware could shatter (it being thin) if under too much pressure from the gas. Not that I plan on creating too much, as small batches is what I wanted to try, before I understood it all. It's fine reading the book of Hoke, but at some pint I need to bite that bullet and try the techniques.

So, simple method is what I'll try to start, so will use what I have at my disposal (I have glass and PVC beakers to 2000ml, so these should be good to act as the reaction chamber walls - weighted down of course).

Thanks for the advice guys

 

[Yggdrasil]

I'm not familiar with the flasks and e-ductor pump method, and was going simple to start with. A beaker weighted down does seem like a method I was going to go with but thought that as the glassware could shatter (it being thin) if under too much pressure from the gas. Not that I plan on creating too much, as small batches is what I wanted to try, before I understood it all. It's fine reading the book of Hoke, but at some pint I need to bite that bullet and try the techniques.

So, simple method is what I'll try to start, so will use what I have at my disposal (I have glass and PVC beakers to 2000ml, so these should be good to act as the reaction chamber walls - weighted down of course).

Thanks for the advice guys

The reason for the bell jar is that they are heavy so they will not float up easily.
That means you will have a slight depth and pressure to overcome, which in turn will give you slightly better retention time.

Here is an example of what I'm calling a flask train, substitute NaOH with H₂O₂ and you will form a weak Nitric.

 

[Sancho_n_Pedro]

My guess is glass tubing is best, but PVC tubing will also do the job here?

 

[duke]

Maybe an inverted funnel.

Skip to 3:15.....Could give you some ideas, but I don't know how efficient it is.

 

[billgold]

I don't know about PVC, but I believe Vinyl is resistant to fuming nitric acid. Either Nile Red or NurdRage, has a video on how various gloves react to fuming nitric.

 

[Yggdrasil]

I don't know about PVC, but I believe Vinyl is resistant to fuming nitric acid. Either Nile Red or NurdRage, has a video on how various gloves react to fuming nitric.

There won’t be fuming Nitric in the pipes/tubes “only” NOx gases.