Just on the chance that we have to go beyond all available filter cartridges, chlorine, etc., how does one built a good water filter. How does one produce "activated" charcoal. In addition to sand and gravel, what are other common, effective materials?

Me.

-- Floyd Baker (fbaker@wzrd.com), November 19, 1998

Answers

We went out tonight and bought The Handy Science Answer Book. A good deal for 5 bucks on the sale table at Borders. Haven't looked at much of it yet but think its already returned the cost. Here's the text on activated charcoal.

"Activated charcoal is an organic substance, such as burned wood or coal, that has been heated to approximately 1,000 degrees F (537 deg. C) in a controlled atmosphere. The result is a fine powder containing thousands of pores that can rapidly absorb toxins and poisons. Activated charcoal is used medically in the treatment of drug overdoses and poisonings."

Not a tremendous amount of detail but enough to work on. I would take it that "controlled" meant something like *contained*. Does it then follow that you can stuff small coal into a large pipe and cap the ends for cooking? I don't have any idea what 1000 degrees would take to produce but is it possible that it would be as easy as putting the pipe into the middle of a bed of red hot coals for a sufficient amount of time? Til the pipe glowed? Tell me if there is another better way. I don't believe there would be enough expansion of the enclosed air to worry about explosions but what about the methane from the coal? If this proceedure, or whatever is the right one, does the job, the resultant "fine powder" could be put into a cloth sack to hold it in place in a filter, between the other elements of sand, gravel, etc. You could build yourself a filter of any capacity you needed using a pool filter tank or 55 gal. drum, etc. I found food grade D-E at nurserys for debugging our beans but its not cheap enough that way to think about using large amounts in a water filter. Unless it was able to be cleaned and reused. That doesn't seem likely though. The stuff is like baby powder. But; if it is reusable and/or cheap, would it be worth using?

Any thoughts on any of the above?

Thanks.

-- Floyd Baker (fbaker@wzrd.com), November 19, 1998.

Floyd, unless you drill a 1/16" hole in your pipe, you will generate a wonderful pipe bomb. I forget the coefficient of expansion for air, but a 1K degree increase is likely to generate a several atmosphere increase in pressure from the air. There are other solids which will sublimate at that temp and the coef of their expansion would NOT be negligible. And yes, I understand we are really talking about a 587 +/- a few (37?) degree (C) increase but who's counting!

cr

-- Chuck a Night Driver (rienzoo@en.com), November 20, 1998.

O.K. so the 1/16th hole will let out the pressure and gas and still allow the material inside from being consumed? How hot would a fire actually get that pipe? 1000f or 587c isn't out of reach in a wood fire, is it?

BTW; I didn't really believe it could be done totally enclosed. At least I wouldn't have stood close while it was heating up. :-)

-- Floyd Baker (fbaker@wzrd.com), November 21, 1998.

I'd like to continue this thread on making "activated charcoal" a little further. IMHO, it seems to be worth more consideration.

Has anyone actually made "activated charcoal"? What are some actual proceedures? Can wood charcoal be heated in a pipe, in a fire, to the required 1000 degrees? How much is needed and how long is it good for? Maybe we have to convert some fish tank filter replacement schedules?

Can we get some real survivalist nitty gritty here? Obviously water filters stand a good chance of being the ultimate survival tool. People should know how to make one.

And not to get away from the main thought but, what about *reversing* the Chemistry 101 seperation of h & o into their seperate selves. It probably can't be done simply, using welders tanks of hydrogen and oxygen, but it is being done in so called "fuel cells" (?) in the space stations. It is probably a very small amount and no doubt prohibitively expensive and complex but then again, as I've said before, I don't know everything.

Me.

-- Floyd Baker (fbaker@wzrd.com), November 29, 1998.

Wood fire doesn't get that hot - (paper, light wood are similar, ignites at 451 deg F.

This "whole subject" of activated charcoal should illustrate even how the basic principles of industrial process go into very, very specialized knowledge very, very quickly. I've gpt to look it up - if I forget, remind me via this thread - okay?

The second - do you want to make power, or generate oxygen-hydrogen, or make water? How do want to use the fuel cell? What are you starting from? How long will you need power? (Related to what is the best source of fuel.) How much power? What "stuff" do you have now to work with?

-- Robert A. Cook, P.E. (Kennesaw, GA) (cook.r@csaatl.com), November 29, 1998.