Media for Fumehood

[Bingtan]

Hi,

I wanted to ask what do you guys use as media for your Fumehood. Was kind of getting anal with the mercury fumes lately and was curious if a hepa filter or aldehyde filter be enough before releasing air to the environment..

Would appreciate your inputs. Can’t get the chemistry out of the photograph making.

Sincerely,

Bing

[James Rader]

I am not a chemist or safety expert, but from what I have learned, an activated charcoal filter is what you need. HEPA, and especially aldehyde, would be a bad choices. HEPA filters by size, using fiberglass, and would be expected to let mercury through. An aldehyde filter would risk generating alkylated mercury compounds, like potentially methylmercury. That could be worse than the mercury alone.

[jgmotamedi]

I don’t think you should use a recirculating fume hood with mercury. The risks are too high. Vent it outside, or if you prefer into a activated charcoal filter outside.

[Bingtan]

hi guys,

thank you. actually just felt bad that I will be releasing the air into the environment without any sort of filtering so had wanted to at least use some for of media before releasing it out to the air.

[Andy Stockton]

In industrial settings activated charcoal impregnated with sulfur compounds is used to trap mercury and prevent release into the atmosphere. The problem in a home setting using this approach is two-fold. First, there is no way to measure if the adsorbent material has reached capacity and is no longer functioning, and second, the used activated charcoal has to be disposed of as toxic waste. With some research you could probably decide on a time schedule for replacing your filters, but to be certain of zero release you would probably want to err on the conservative side and replace fairly frequently. There is some cost involved in that approach.

While the amount of fumes released during mercury development is sufficient to endanger the operator in a confined space (thus the use of fume hoods) released to the atmosphere it adds a negligible load to the existing mercury burden. Within moments it is at concentrations that would be difficult to even measure. Generally ensuring that your exhaust opening is at a sufficient height is an adequate safety precaution.

If it is very important to you to not even add minimally to environmental mercury loads, activated carbon filters impregnated with sulfur are available and would work. Some research would help you determine a replacement schedule and identify a location that would accept the resultant toxic waste for safe processing.

Per jgmotamedi’s post, these comments apply only to fume hoods that exhaust externally. I strongly discourage any home practitioner from using a recirculating fume hood for mercury development.

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