Kids, have you heard that necessity is the mother of invention?  For those of you with asthma who can use some help in the room-deodorizing department, there is hope. The answer is homemade, all-natural, essential oil powered, gel based air fresheners.  They smell great.  They last a good long time.  They are cheap to make.  They have five ingredients you can find at any grocery or department store.  And chemistry can explain how it works! 

Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

First a word about essential oils: they’re powerfully scented and a little goes a long way, so go easy on how much you add.  You don’t want to add more than 30 drops per air freshener until you know just how strong your oil is.  Here is a basic air freshener recipe, with a few favorite scent combinations below.

You’ll need:

• 1 ounce granulated or powdered gelatin
• 2 cups cold water, divided
• 20-30 drops of essential oil
• 1 Tablespoon salt
• food coloring
• a small saucepan and stove for heating it
• heat-proof jars to hold the hot dessolved gelatin liquid
• a disposable chopstick or skewer to use as a stirring stick

Watch an adult partner do the following steps. Bring one cup of water to a boil in a small saucepan.  Sprinkle the gelatin over the boiling water and stir until smooth and all of the gelatin is dissolved. Add the salt and the second cup of cold water and stir. Set aside. Add essential oil and food coloring to the jar(s).  Quickly pour the hot dissolved gelatin over the essential oil and food coloring.  Stir until evenly colored. Allow to cool uncovered on a heat-proof surface. When cooled, keep covered until ready to use.  When ready to use, uncover the jar and place it wherever you want a lovely scent.

An essential oil is a concentrated liquid containing volatile aroma compounds from plants. An oil is "essential" if it carries a distinctive scent, or essence, of the plant. They are used in perfumes, cosmetics, and soaps, for flavoring food and drinks, and for adding scents to household cleaning products.

Gelatin is a translucent, colorless, flavorless solid derived from collagen.  It is found in gummi candies, marshmallows, gelatin dessert, and some ice cream, dip and yogurt.  Gelatin is classified as a food.  When you dissolve the gelatin powder in hot water, you break the weak bonds that hold the collagen protein chains together. Each chain is a triple-helix that will float around in the bowl until the gelatin cools and new bonds form between the amino acids in the protein. Scented oils and colored water fills in the spaces between the polymer chains, becoming trapped as the bonds become more secure. The gel is mostly water.

Some Scent Combinations:

sweet basil and lemon air freshener

• 20 drops Sweet Basil essential oil
• 8 drops Lemon essential oil

rosemary orange air freshener

• 25 drops Sweet Orange essential oil
• 5 drops Rosemary essential oil

fresh pine scent air freshener

• 25 drops Fir Pine essential oil
• 3 drops Lemon essential oil
• 2 drops Sweet Orange essential oil
• 1 drop Bergamot essential oil

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Kathleen Carrado Gregar, PhD, Argonne National Labs 
[email protected]
February 2013

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References:
Thanks to Emily Neis for telling us about this idea.
http://www.foodiewithfamily.com/2010/03/17/homemade-essential-oil-air-fresheners/
http://chemistry.about.com/od/foodcookingchemistry/a/how-jell-o-works.htm