Liquid CO2 for clothes washing

Quaoar · 2014-03-26 10:14:49

I found this interesting paper by Tom Hill, who suggests to use liquid CO2 for clothe washing, saving a lot of precious water.

http://www.marspapers.org/papers/Hill_2000.pdf

Last edited by Quaoar (2014-03-26 10:15:25)

SpaceNut · 2014-03-26 19:24:26

That is not to far fetched to use since we could create it more easy from the crews own recycling system.

Quaoar · 2014-03-27 02:13:32

CO2 production is almost 1 kg/person/day: it can be liquefied and used for washing clothes, before be cracked and recycled.
Another option may be to use special clothes that don't need to be washed: I remember a Japanese astronaut on ISS experimented a special idrorepellant uderware, that can be used for more than a month without be washed, but I cannot find any data.

GW Johnson · 2014-03-28 10:16:13

You still need some sort of dirt and grease solvent in your CO2, the analog to detergent in water. Liquid CO2 would be an analog to dry-cleaning. Not sure what that additive is, but I'd bet one already exists.

Liquid CO2 does require high pressure. Your washing machine would be pretty heavy, because it would have to be very stout.

GW

Quaoar · 2014-03-29 05:09:06

GW Johnson wrote:

You still need some sort of dirt and grease solvent in your CO2, the analog to detergent in water. Liquid CO2 would be an analog to dry-cleaning. Not sure what that additive is, but I'd bet one already exists.
Liquid CO2 does require high pressure. Your washing machine would be pretty heavy, because it would have to be very stout.
GW

Please correct me if I'm wrong: CO2 is not a dipolar molecule like water, so grease can solve in it without need of a solvent.
The problem may be the mass of the washing machine, but assuming it's three times a conventional washing machine and that it can save 5 liters of water/day, in a 860 days travel we have speared more than four tons of water.

RobertDyck · 2014-03-29 11:09:12

Soap and detergents are called "surface acting agents" or surfactants. Their molecule bonds to grease at one end, and the other end has something that dissolves in solvent. Water is a weak solvent, but universal because it's both polar and ionic at the same time. CO2 is neither polar nor ionic. That means it won't dissolve anything as well as water. But if you add a little water to liquid CO2, then it will form carbonic acid. That's ionic. So detergents should dissolve in that. Of course that means you're washing in weak acid. Will that degrade your clothes?

I still think it would be simplest to land where there's plenty of water ice. And your habitat will recycle wash water. Then we can simply wash in water, like we do on Earth.

Quaoar · 2014-03-29 13:33:13

RobertDyck wrote:

I still think it would be simplest to land where there's plenty of water ice. And your habitat will recycle wash water. Then we can simply wash in water, like we do on Earth.

It would be surely better, because we can also make ISPP without bringing hydrogen from Earth: at the moment the only site with known water ice is Ice Lake in Vastitas Borealis, but nobody likes it because it's 70° North.

Last edited by Quaoar (2014-03-29 13:34:13)

RobertDyck · 2014-03-29 15:27:21

Bending water with static electricity. My high school chemistry teacher did this. Rub silk on a glass rod, or cat's fur on a rubber rod.
http://www.youtube.com/watch?v=w8Z7HuA07to

Josh Cryer · 2014-03-30 02:03:54

On Mars, it's not really necessary, water is almost everywhere. Certainly the lower latitudes are literally full of water. At times a cubic meter of soil is half water.

On the travel to Mars, this is an interesting argument, but you got to understand, clothes / dirtiness / smells / filth is minimized. You're not washing your clothes daily, as long as you don't have an accident you'll probably last weeks in the same pair of clothes before you or your shipmates are repulsed by the smell. You're not going to be super active, you're not going to smell any worse than the smells generated by the internal sewage systems (as far as I understand on the ISS, they aren't that great, and you get used to it).

This is, imo, especially true if you use a Mars-direct type system. You'll stink, but you'll get used to it. In summation, traveling there may be gross, but once you land, you're going to have water, natures solvent, to take care of things (water actually doesn't require detergents, you can wash without them, it just takes more effort / cycles to get the same result; detergents just make it easier and get rid of potential staining; if you don't care about that you don't need detergents).

Quaoar · 2014-03-30 04:42:24

Josh Cryer wrote:

On Mars, it's not really necessary, water is almost everywhere. Certainly the lower latitudes are literally full of water. At times a cubic meter of soil is half water.
On the travel to Mars, this is an interesting argument, but you got to understand, clothes / dirtiness / smells / filth is minimized. You're not washing your clothes daily, as long as you don't have an accident you'll probably last weeks in the same pair of clothes before you or your shipmates are repulsed by the smell. You're not going to be super active, you're not going to smell any worse than the smells generated by the internal sewage systems (as far as I understand on the ISS, they aren't that great, and you get used to it).
This is, imo, especially true if you use a Mars-direct type system. You'll stink, but you'll get used to it. In summation, traveling there may be gross, but once you land, you're going to have water, natures solvent, to take care of things (water actually doesn't require detergents, you can wash without them, it just takes more effort / cycles to get the same result; detergents just make it easier and get rid of potential staining; if you don't care about that you don't need detergents).

But astronauts has to do a lot of sport to not hypotrophize muscle and hearth: during travels if they have a full gee spinning ship an intensive training can be avoided, but on Mars surface, with only 0.38 gee, I think 2 or 3 hours/day of gym will be necessary. So a water source is necessary.
Ice Lake is too north. Buried glaciers on mid latitude (25-35°) may be a good compromise, but are we certain that water are still present and we can find with a less than 50 meters drill?

Last edited by Quaoar (2014-03-30 04:45:03)

RobertDyck · 2014-03-30 05:24:06

Could we use washing soda instead of detergent? This is a simple enough chemical that we could make it on the spacecraft: Na2CO3

Solvay process:
NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl
then heat
2 NaHCO3 → Na2CO3 + H2O + CO2
then to recycle ammonia
CaO + H2O → Ca(OH)2
Ca(OH)2 + 2 NH4Cl → CaCl2 + 2 NH3 + 2 H2O

The recycle process consumes calcium oxide, producing calcium chloride. But the overall main process consumes sodium chloride (salt) and CO2 to produce washing soda.

Also, colour safe bleach is ozone. It can be produced with electricity and air. It can't be stored, it decomposes back to molecular oxygen. One appliance manufacturer suggested a component for commercial clothes washers to make ozone during the washing cycle. Didn't catch on because people still had to buy detergent.

Can we filter out washing soda from wash water? Then recycle it?

martienne · 2014-03-30 09:19:04

My impression too, is that if they settle in the right place, water won't be a problem.
So this seems like an attempt to solve a problem not really there.
That said; the idea to use clothes and materials in such a way that minimal clothes washing is needed makes sense. At the end of the day, they didn't travel to Mars to spend their time doing laundry, make a fashion statement, or win "best groomed competitions.

No doubt there'll be plenty of other good uses of recycled CO2.

Josh Cryer · 2014-04-01 05:25:07

Quaoar wrote:

But astronauts has to do a lot of sport to not hypotrophize muscle and hearth: during travels if they have a full gee spinning ship an intensive training can be avoided, but on Mars surface, with only 0.38 gee, I think 2 or 3 hours/day of gym will be necessary. So a water source is necessary.
Ice Lake is too north. Buried glaciers on mid latitude (25-35°) may be a good compromise, but are we certain that water are still present and we can find with a less than 50 meters drill?

Yeah, a Mars Direct style mission with artificial gravity, you can walk around and maybe jog a bit, but again that's like ISS, they're not bathing on the ISS daily, they wipe down after exercise, but it's minimal at best. It doesn't get rid of the odor. Apparently the ISS is really stinky but once you get used to the human vapor smell you forget about it. A Mars Direct style mission, you'd get on a clean smelling ship, and while someone not accustomed to the smell would be repulsed, you'd be very much used to it and it maybe wouldn't even register. Perhaps after getting a clean shower on Mars and re-entering the pod you'd notice the stench, but not while traveling.

Anywhere north of +45 or south of -45 or in Hellas Planitia has water ice as much as constituting half the soil. Mars has a lot of water, it's just frozen in the soil. You will likely land in the lower areas because you want access to that water and the meager protection from cosmic rays. Phoenix proved this subsurface water ice when it dug down just a few inches and found it.

GW Johnson · 2014-04-01 09:58:21

ISS is stinky because of two things: (1) they cannot effectively bathe, yet must exercise tremendously to stave off microgravity diseases, and (2) there is no way to do laundry in zero gee (I suppose there could be, but that hardware has yet to be invented).

Artificial gravity solves both problems, and a lot more besides. With artificial gravity, you can even do conventional cooking with free-surface liquids, and conventional water/wastewater treatment. Takes more than just a medical centrifuge module, though.

4 rpm is tolerable, long term. 3 rpm "for sure". At 4 rpm, the radius to provide 1 gee is "only" 56 m. The trick is doing that without resorting to uncontrollable Rube Goldberg stuff with cables, or building gigantic Battlestar Galacticas that no one can afford. But, there IS a way to do it.

GW

SpaceNut · 2021-01-24 17:31:16

For Mars we will likely use compressed co2 to clean the space suits before we even go into the air locks where we may even do more cleaning to keep the regolith out of the habitat spaces.
The calcium is locked up in perchlorates and if we can break that bound we will be able to make a soap for inside use as RobertDyck post #11 indicates.

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#1 2014-03-26 10:14:49

Liquid CO2 for clothes washing

#2 2014-03-26 19:24:26

Re: Liquid CO2 for clothes washing

#3 2014-03-27 02:13:32

Re: Liquid CO2 for clothes washing

#4 2014-03-28 10:16:13

Re: Liquid CO2 for clothes washing

#5 2014-03-29 05:09:06

Re: Liquid CO2 for clothes washing

#6 2014-03-29 11:09:12

Re: Liquid CO2 for clothes washing

#7 2014-03-29 13:33:13

Re: Liquid CO2 for clothes washing

#8 2014-03-29 15:27:21

Re: Liquid CO2 for clothes washing

#9 2014-03-30 02:03:54

Re: Liquid CO2 for clothes washing

#10 2014-03-30 04:42:24

Re: Liquid CO2 for clothes washing

#11 2014-03-30 05:24:06

Re: Liquid CO2 for clothes washing

#12 2014-03-30 09:19:04

Re: Liquid CO2 for clothes washing

#13 2014-04-01 05:25:07

Re: Liquid CO2 for clothes washing

#14 2014-04-01 09:58:21

Re: Liquid CO2 for clothes washing

#15 2021-01-24 17:31:16

Re: Liquid CO2 for clothes washing

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