SAI Impacts on Airplane Air Quality Update: Part 1

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Alvia Gaskill

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9:49 AM (8 hours ago) 9:49 AM

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Further research has identified KOH, NaOH, KI or KMNO₄ impregnated activated carbon as a possible H₂SO₄ removal technology for airplanes flying above 60ºN with SAI in place. The strong base scratches the carbon surface, creating chemisorption sites in addition to those already present for physical adsorption of VOCs.

Most applications and verification studies have involved SO₂, so the applicability to H₂SO₄, etc. is inferred and will require laboratory and field validation. But it does appear that combined with moving the ECS filtration to before the bleed this could solve the problem described in the paper.

Other problems will result which will have to addressed. The levels of concern are still quite low in terms of measurement limits. The low levels may also not result in good removal efficiency which will need to be determined.

The airlines will have to eat the extra fuel charge due to reduced thrust which is a small price to pay since the alternative may be not flying at all! Cabin air is generally very low relative humidity (5-20%) and is why you can easily get dehydrated on a long flight. If any of these compounds are used, the cabin air may have to be humidified, otherwise, uptake may be low. Humidification will also increase corrosion. So, there are a number of tradeoffs to be worked out.

A commentor asked about background levels of H₂SO₄ in ambient air and how this might impact the retrofits and monitoring. While SO₂levels are generally <25 ug/m³over the U.S. they are much lower above 60ºN. H₂SO₄is in the ppt except in areas where sulfur containing volcanic emissions are found. So, while calculating health risk levels is easy, measuring them is a different issue.

A Guide To Impregnated Activated Carbon | General Carbon Corporation