It’s easy to make a homemade desiccator to protect items from humidity and remove moisture from ones that get wet. For example, use a desiccant container for drying out a damp cell phone, keeping crackers crisp, and protecting fabrics from mold or mildew. Here is how you make a desiccator and a look at readily available desiccants and their uses.
What Is a Desiccator?
In a lab, a desiccator usually is a large piece of glassware consisting of a few key parts.
- Bottom section that holds desiccant.
- Perforated divider that separates the chemical from the other desiccator content.
- Lid that seals. Often, this is a ground glass lid that seals using vacuum grease.
- Some desiccators have a stopcock that lets you pump a partial vacuum.
These devices preserve moisture-sensitive items or remove residual moisture from nearly-dry items. Common desiccator chemicals are silica gel, calcined quicklime, calcium sulfate (Drierite), or calcium chloride.
Desiccants and Their Uses
Desiccants are hygroscopic chemicals. Fortunately, the ones scientists use in a lab setting are also readily available as common household chemicals.
- Silica gel beads
- Activated charcoal
- Calcium chloride (road salt or solid bleach)
- Calcium sulfate (plaster of Paris or gypsum)
- Zeolite
- Rice
- Table salt (sodium chloride)
- Bentonite clay (from a gardening store or as kitty litter)
- Sugar (sucrose)
- Magnesium sulfate (Epsom salt)
- Quick lime (calcium oxide)
- Sodium hydroxide or potassium hydroxide (lye or solid drain cleaner)
Which chemical you use depends on availability and your intended use. Silica gel and activated charcoal are safe, general purpose desiccants. A few desiccants are safe for use around food. For example, use rice, salt, sugar, or activated charcoal for keeping dry good crisp.
Use caution with quick lime, sodium hydroxide, or potassium hydroxide. They are highly effective, but are caustic and can cause chemical burns. Also, keep in mind, sodium hydroxide, potassium hydroxide, and calcium chloride all eventually dissolve in the water they absorb. For most uses, you’re probably better off choosing another chemical from the list.
A homemade dehumidifier is like a desiccator on steroids because it removes moisture from a whole room. Here’s what you do.
Make a Desiccator
Making a desiccator is super easy. All you do is place a small amount of desiccant in a container that can be sealed.
- Zip-top plastic bag
- Jar with lid
The advantage of using a plastic bag is that you can push out air, which contains water vapor. The advantage of using a jar is that you can keep the desiccant from being in contact with your item. Just pour the desiccant in a small dish and place it inside the jar. Alternatively, pour the chemical directly into the jar, but place you item in a small dish on top of the desiccant.
How to Recharge a Desiccator
Eventually, the desiccant absorbs or adsorbs all the water it can hold. One option is replacing the chemicals. However, you can recharge desiccant chemicals by driving off the water. Do this by pouring the chemical onto a baking sheet and heating the pan in a warm over. After cooling, store the dry chemical in a sealed container until you’re ready to use it.
References
- Alexeyev, V. (2000). Quantitative Analysis. University Press of the Pacific. ISBN: 0898750342.
- Chai, Christina Li Lin; Armarego, W. L. F. (2003). Purification of Laboratory Chemicals. Oxford: Butterworth-Heinemann. ISBN 978-0-7506-7571-0.
- Flörke, Otto W., et al. (2008). “Silica” in Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a23_583.pub3
- Lavan, Z.; Monnier, Jean-Baptiste; Worek, W. M. (1982). “Second Law Analysis of Desiccant Cooling Systems”. Journal of Solar Energy Engineering. 104 (3): 229–236. doi:10.1115/1.3266307
- Williams, D. B. G.; Lawton, M. (2010). “Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants.” The Journal of Organic Chemistry. 75: 8351. doi:10.1021/jo101589h