[bones]

I want to start refining gold and possibly other metals at home, and I can't find much information through Google about what kind of filter is needed in a fume hood to scrub nitrogen dioxide.  Since I'll be doing this at home and my neighbors live in a rather close proximity, I feel as though it would be unfair to them to just set up a fan and blow the nitrogen dioxide away from my house, so I really want to get a relatively cheap fume hood that can handle NO2.  Any info on this at all would be greatly appreciated.

[pcm81]

This suggestion should be reviewd by more experienced chemists, but my 1st thought would be to bubble it through cold water. May be add some iron to water or another metal, to keep nitric acid concentration low and form nitrogen salts. Possibly adding a small amount of NaOH will help to convert NO2 to nitric acid, which then be reduced to salt of NO3-???

[bones]

I've started doing some reading on NOx scrubbers and apparently alkaline peroxide solutions are good at scrubbing NOx.  Maybe I'll test it out by reacting some copper with nitric acid and see how well it works.  Peroxide mixed with nitric acid seems to work by turning the NOx into more nitric acid and nitrous acid.

[pcm81]

I've started doing some reading on NOx scrubbers and apparently alkaline peroxide solutions are good at scrubbing NOx.  Maybe I'll test it out by reacting some copper with nitric acid and see how well it works.  Peroxide mixed with nitric acid seems to work by turning the NOx into more nitric acid and nitrous acid.

That matches my understanding as well. When you bubble NO2 through water you will eventually reach saturation and rest of NO2 will pass through water. The reason why i suggested adding metal to water is to reduce concentration of nitric acid, hence shift the equilibrium towards enabling you to make more nitric acid from dissolved NO2, same for NaOH... reduce concentration of nitric acid. If you have hydrogen peroxide, that will hellp in conversion of NO2 to nitric acid. May be just use the 3% H2O2 from the store in place of water?

May be sodium percarbonate in water solution is what you need?

EDIT:
I am also thinking you can add a dash of potassium carbonate (cheap on amazon). Potassium carbonate should react with nitric acid, to produce CO2 and Potassium Nitrate, which is poorly soluble in water  (242g/L at 20*C) and will eventually precipitate. May be you can monitor how well your filter is working by precipitate of potassium nitrate.