What should be done with the carbon when using magic to get oxygen from carbon dioxide?

Question

So, I'm working on a flintlock fantasy series, and my protagonist is what's called an Arcane Engineer. This is someone who makes magical devices. Among those she has made there is a mask that let her breathe both underwater and in environments where there's smoke or other gases that would be bad to inhale.

My thinking is that the masks works by converting the CO2 she exhales into O2, similar to the way plants do when they perform photosynthesis. However, this leaves the issue of what to do with the carbon in the carbon dioxide. The temperature of atoms would not be changed, only how they are arranged into molecules.

Any other gases she exhaled are not affected and simply pass through the mask. When she inhales, any CO2 in the air is likewise converted, benign gases are permitted through, and toxic gases are blocked.

So: What should the mask do with the carbon? That's what I'm trying to figure out right now. The answer will have some effect on how the mask is designed. (Like if it has to have some kind of container where the carbon will go after it is separated from the O2.) Suggestions?

Answer 1

You don't need to expel any carbon

There is actually a set of non-magical chemicals and reactions that can do exactly what you want, the magical part would be regenerating the "waste" chemicals back to the reactive form, keeping the temperature stable (some reactions are exothermic), and facilitating the reaction like a catalyst.

For converting carbon dioxide to oxygen, you can use a lithium peroxide reaction, which produces lithium carbonate and oxygen. Exhaled air is about 5% carbon dioxide, with a similar drop in oxygen content. Since the reaction of lithium peroxide is 2:1, this can enable you to breathe underwater if you provide half the oxygen, remove the exhaled water vapor and toxins, and regulate the pressure with inert gas such as nitrogen or helium.

Generation of nitrogen gas can be done in a separate partition by mixing liquid ammonia with hydrazine (using a magical catalyst), not a lot is needed since it is only there to replenish small amounts of removed impurities to balance the pressure and volume of air. This produces pure nitrogen and hydrogen gas, the hydrogen is expelled externally into the water or stored to produce pure water from air later.

For gas exchange, you would need to convert about 20ml of carbon dioxide per breath to oxygen at standard air pressure, at 2kg per cubic meter, that is around 40mg of carbon dioxide, requiring full utilization of 32mg of lithium peroxide. If you store say, 80 grams in the mask (about the weight of a respirator cartridge), that gives you 2500 breaths or 2 hours at normal exertion. If you are swimming or running you would have substantially less, maybe only 30 minutes, this is assuming there is no magical autoregeneration happening while you are breathing. You also need enough material and surface area for complete reaction, but this should not be a problem at the given utilization rates.

In other environments, where the mask filters out particulates and toxins, you would be more interested in getting rid of carbon monoxide from smoke. This is done by adding oxygen to produce carbon dioxide, at levels that are not toxic or could be removed by reaction.

In low oxygen environments or underwater where you need it, sodium chlorate can decompose into salt and release pure oxygen gas in the process. Generally this is a very high temperature reaction, magic would be needed to keep this safe in a mask. 160g of chlorate produces enough oxygen for around 1 hour of normal breathing in a no air environment, or 2 hours when combined with CO2 conversion. Magic could then be used to regenerate the salt into chlorate with a fresh oxygen or water source later, or it could just be replaced with new chlorate if salt is impervious to magic in your world. You can make it with electricity and hot salt water.

Designing a mask

Because of the different functions of both filtration, waste removal, and oxygen generation, the mask would need to be layered and partitioned. The outer layer (filtration) and inner layer (conversion) would need to be separated if needed, and an air bladder in the middle for breathing.

Underwater, the outer layer is isolated from the outside which is now water. The exhalation valve is shut off, and the nitrogen gas generator takes its place. The CO2 conversion layer is simply powder in a filter media that exhaled air passes through, it would normally leave the exhalation valve, but now underwater it goes through the filter and into the expanding air bladder, converting the CO2 to O2 as it passes through twice.

The outer layer is then routed back to the inner layer before the bladder, to slowly remove toxins and water vapor from the breath. The oxygen generator would be the closest to the mouth and work on a feedback mechanism, if O2 is low it makes more. The O2 generator also needs to be hooked to the outer layer to convert carbon monoxide to dioxide.

Magical components should keep the mask similar in size and shape to a standard half-face cartridge respirator mask like a 3M 7500 series with a little more bulk where the cartridges would attach, and an air bladder that expands out the side or bottom like a frog croaking. Depending on how much magic you want, the air bladder, exhalation valve, and separator valves could be replaced with force shields, further reducing the size and weight of the mask. The reactant weight would be around 240g in powder and maybe 50 in liquid. Removing CO2 increases the weight, but making oxygen reduces the weight, so the weight of the mask will vary a little with use, but not much. Ammonia and hydrazine can be provided by small ampules with rubber plugs, that are easily replaced when expended.

Chemically, all reactions are done without violating the laws of thermodynamics or by using cold fusion or alchemy. They could even be regenerated without magic at all, by adding fresh reactants by hand, and the magic components only acting to catalyze and regulate the reactions. A magical regneration of lithium peroxide at the rate that would be used by heavy breathing in normal air (1g per hour), or higher, would be ideal. That way you do not need manual exchange of the powder, and it adds a plot point if you have used it up underwater and now need it to regenerate. That is 80 hours of no mask use for full regeneration if fully depleted, mask use would pause generation but it would still be able to remove carbon monoxide.

The outer toxin filter would be the same design as those used today, activated carbon combined with reactants and chemical treatments, and a particulate blocking media, something like cellulose or rayon. It could be magically enhanced to continually clean itself or last longer than a non-magical filter.

The mask itself, plus the reactants, magical components, and outer filter would weight maybe 1.5 to 2.5 pounds, depending on mask material. I am assuming you do not have plastics, so probably leather and refined metals like aluminum or titanium, maybe held together with spider silk.

Answer 2

Use the carbon to add new activated carbon to the mask filter. Though ineffective against toxic gases, active carbon is good at capturing other contaminants.

Activated carbon, also called activated charcoal, is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Activated is sometimes substituted with active.

Due to its high degree of microporosity, one gram of activated carbon has a surface area in excess of 3,000 m2 (32,000 sq ft) as determined by gas adsorption.

Filters with activated carbon are usually used in compressed air and gas purification to remove oil vapors, odor, and other hydrocarbons from the air. The most common designs use a 1-stage or 2 stage filtration principle in which activated carbon is embedded inside the filter media.

Activated carbon filters are used to retain radioactive gases within the air vacuumed from a nuclear boiling water reactor turbine condenser. The large charcoal beds adsorb these gases and retain them while they rapidly decay to non-radioactive solid species. The solids are trapped in the charcoal particles, while the filtered air passes through.

Answer 3

Honestly, I'd just have it release as elemental carbon or carbon black. I think it would be an awesome visual if every exhale came out as a puff of smoke or soot

Answer 4

She is exhaling 2 molecules containing water: CO2 and H2O. Use both.

Our metabolism: CHO + O2 -> CO2 + H2O

CHO here is carbohydrate; food.

Plants run it backwards: CO2 + H2O + light -> CHO + O2.

If you are getting biochemical, go all the way. Using both gases she exhales provides her more oxygen and also yields a bunch of hydrogen. Carbon likes hydrogen: put them together without oxygen and you have methane.

Thus: her magic machine makes methane. On land she could light it and have a flame on top of her head which is a good look for a magic user.

Using H2O as a O2 source might come in handy underwater where there is plentiful H2O. Her machine might then produce an excess of hydrogen which will bubble away.

Answer 5

As a side effect your mask makes diamonds, about 1 carat a minute.

3 hours of use gives a diamond sphere just over an inch in diameter, or something the size of the Daria i Noor

These are all rough figures, but a human produces about 1kg of CO2 per day, and CO2 is about a quarter carbon by weight, so allowing for the extra exertion (~15%) of swimming or moving through water that's about 0.2g per minute

0.2g per minute is 36g in three hours.

Answer 6

Why not just use the magic to transmute the carbon to more oxygen? Four carbon atoms contain exactly what you need to make three oxygen atoms.

Answer 7

How powerful is your magic? Can it teleport the atoms? I am thinking a huuuge diamond slowly building itself on a shelf in your Arcane Engineer home.

Answer 8

My thinking is that the masks works by converting the CO2 she exhales into O2, similar to the way plants do when they perform photosynthesis.

Do it like plants do and keep it in the body. But make lipids rather than sugars, because magic and because that way you are more oxygen-efficient.

Here are some lipids she can do. Triglycerides in particular are an amazing source of energy. They store more than twice as much energy per mass than sugars or proteins.

And if you think this precious energy storage would be undesirable because in real life this usually gets stored in the abdomen, remember that:

• Some people like that
• If she doesn't, she may use her magic to make it go somewhere else as she sings "because you know I'm all about that bass, 'bout that bass, no treble".

Edit: OP commented:

Well, if you check my Deviant Art profile (under Patrick-Leigh,) you'll find my journals on my character's physiology, and, yes, she is "all about the bass." (She's a Half-Orc, so she has to keep a certain amount of body fat on her or she'll burn through it too quickly and start losing muscle mass.) That, actually, makes the idea of the mask also proving her with sustenance all the more viable. It's restricted by the whole conservation of mass thing, so she'd need to get the other atoms to form the triglyceride molecules from somewhere. Any ideas on that?

The formula for a triglyceride such as a molecule of unsaturated fat is C₅₅H₉₈O₆.

So, she needs 55 carbons. That would release 110 oxygen atoms. If she sacrifices of those 6 to make the triglyceride, she would still be recycling over 90% of the oxygen she uses. Makes for very long dives, but she would have to resurface at some point.

There is a better solution. She will also need 98 hydrogen atoms, so she will have to break water. She either breaks 49 water molecules from her surroundings (with help of the mask), or she takes it from her own body. In this way, she gets all the hydrogen she needs, and 43 extra oxygen atoms on top of the ones she recycled (remember, six of those oxygen atoms are to form the triglyceride).

If taken from her own body, she will need to break approximately 1.3 liters of water for every 1.5 kilograms of fat she makes.

So now you have recycled all of your oxygen AND got almost 50% extra. What do you do with that excess oxygen? Don't breath that, gas mixtures with more oxygen than we need are poisonous. Instead, you can form ozone (O₃) in the mask. Ozone is a powerful disinfectant, it can destroy a lot of microbes and many viruses. It also has a pleasant smells in low concentrations. You can just cycle a little ozone at the front of the mass and release most of it to the surrounding water. Don't breath the ozone, though, as it can damage the lungs.

Answer 9

What about turning the carbon into plant material? That's what happens in photosynthesis. Almost all the mass of a plant comes from carbon extracted from the air.

A nice magical effect would be if small flowers collect at the bottom of the mask. This will limit the time a mask can be used, though it takes a LOT of carbon dioxide to make even a single flower. A perhaps more steampunky, but less colorful, effect would be to have algae accumulate on the inside of the mask, slowly obscuring sight.

Answer 10

So I know this is supposed to be a fantasy universe, but if you are producing excess carbon with nowhere to go, why not use it for production of materials made purely out of carbon. Someone earlier mentioned diamond, but alternatively modern material science has given us carbon nano-tubes and graphene, both of which could be used to incredible ends.

Carbon nano-tubes are insanely strong and it has been recently discovered that there were naturally occurring carbon nano-tubes in Damascus Steel, which already has a legendary reputation as a lost technology. We of course have stronger steels today thanks to modern refining capabilities, but it was generally considered the strongest steel of the time.

Graphene on the other hand is still incredibly experimental, but there have been experiments in using sheets of graphene to produce cloaking materials (like serious scifi cloaking). Alternatively, graphene has incredible potential for computer science, which I imagine isn't likely to be super prevalent in a fantasy world, but there's potentially to come up with something interesting.

So that gives you three strong candidates for potentially fantastic items. Invisibility cloak, check. Insanely strong sword, check. While you're at it go ahead and make some diamonds for diamond head tools, jewelry, currency exchange, whatever.

Answer 11

Use it as a nutritional supplement or internal deodorizer.

Answer 12

Plants use the excess carbon to build themselves. You could have your mask regenerate itself with the carbon it pulls out.