Sciencemadness Discussion Board

Dehumidifiers

tom haggen - 5-1-2004 at 21:16

Ya, one of my old friends who used to have an indoor garden wink wink, had a dehumidifier to prevent mold on his plants. This dehumidifier consisted of a small plastic dish and a solid white pellet like chemical. The chemical was extremly hydroscopic, It could be NH4NO3, I'm going to find out soon. anyway if it is NH4NO3 it comes in good size bags for 99 cents. i'm going to go to the store and find out. I'll keep you guys posted.

I am a fish - 6-1-2004 at 03:09

Calcium chloride is often sold as a dehumidification agent.

Haggis - 6-1-2004 at 12:05

Yea, most dessicants sold for mold eradication and keeping a dry environment are calcium chloride, CaCl2. Damp Rid, Damp out as well as a lot of other products, they also sell refills which contain roughly the same amount of chloride, but is cheaper. Keep that in mind. Also, there is a product in the midwest and possibly other places too called, IIRC, 'Sno-Melt' It is an 18 or so pound bucket and can be had from 3-5 dollars, although I got mine for free. It is mostly CaCl2, with a few other chlorides mixed in. The substance is all prilled. Some heating may be needed to drive off moisture, but it should be reclaimed easily. Also, powdering or crushing the prills will increase surface area, and speed of dessication.

Mumbles - 6-1-2004 at 18:28

Haggis, I've seen two things that would fit the descripion(also from the midwest btw). One's in a black container and had the other chlorides. The other is Heet brand ice melter. This is what I have, actually for ice melting. There seems to be a coating on it. I think the coating may be CaCO3. If it wasn't coated I'd suspect you'd get a nice jug of liquid ice melter.

I've tested it a bit. The prills alone don't take water very readily at room temp. When crushed, there is usually a solution within a few days during decent humidity weather. When dissolving the prills in water, there is a portion that doesn't dissolve. On crystalisation you are left with what I assume to be mostly CaCl2. This can then be dried and used as a dessicant.

Does anyone know if the comercial products are anhydrous? I think they might be the dihydrate. In school it took quite an effort to get it anhydrous. I suppose industry would have high heat ovens, but I doubt they would go through with the effort.

tom haggen - 17-2-2004 at 22:33

How many different types of liquids will calcium chloride absorb? Is it limited to H2O?

unionised - 18-2-2004 at 15:26

Lots, notably low molecular weight alcohols. Also reacts with amines.