Community

Gasoline, Ethanol and the Scientific Method

With the Biden decision to raise the ethanol limit in gasoline to 15%, the question of getting the ethanol out becomes significant to folks who drive older cars, run small engines, etc.  Fifteen years back, I was at SDSU, and rumors were running that the 10% ethanol maximum wasn’t a reality if you filled up in Minnesota.  There was a lot of ethanol production, and it was cheaper than gas – and I have no idea if it was true.  I could buy ethanol free regular then, so that was my solution.

Still, I did a little research for the sake of my lawnmowers and chainsaw – if I’m remembering correctly 22% ethanol is the most corrosive, most damaging to the little engines and the old engines.  Multifuel engines can handle anything – but lawnmowers, weedeaters, generators and chainsaws are a bit more finicky.  If you want to believe that Joe Biden wouldn’t hurt your chainsaw, fine.  If you don’t want his decisions affecting your small engines, stick with me.

I’m fairly certain that I can actually measure the amount of ethanol in the gasoline I buy.  Frankly, I think I can take the ethanol out of gas and make clean gasoline for my small engines.  So far it seems cheaper just to buy ethanol-free premium – but things may change – and removing ethanol from gasoline is just adapting old technology.

Time was – still is – when our gas tanks would extract water from the air . . . cool, humid air, then the added heat of sunlight, and water would condense on the inside of the tank’s top, form beads, then drop to the bottom.  Once there, it would be picked up by the fuel pump, get into the carb, and with cold weather freeze, block the flow of gas, and stop the car.  The correct response was to add a can of ethanol – I think the brand name was Heet – to the gas.  Since water blends with ethanol much easier than it blends with gas, the ice would lower the ethanol proof a little, move through the carb, then burn up in the engine with slightly decreased efficiency.  It was a cheap and effective way of keeping things going.

Removing the mixed in ethanol just means we do it the other way, and make use of that ancient mechanical device called the settling bowl.  I already have ethanol in my gas – so I can add water to remove it.  Since both water and ethanol are heavier than gasoline, the stuff is going to sink to the bottom of the tank.  Here’s where having a small conical tank, a valve, and a settling bowl can be used to take the ethanol out – and I just realized I don’t have to theorize about how to do it, I can probably google the technique (most of the time someone comes up with my idea before I do).

The search was great: 

Chemists have an old axiom that “like dissolves like” with regard to polarity. That is, polar compounds dissolve other polar compounds and nonpolar compounds dissolve other nonpolar compounds. Water is polar, whereas gasoline is nonpolar. Ethanol exhibits moderate polarity and mixes with gasoline. The ethanol, however, dissolves better in water. Thus, if a person mixes gasoline and water, the two liquids will separate into layers with the water on the bottom. Vigorous mixing of the mixture, however, will transfer the ethanol from the gasoline to the water, where it is more soluble. The separation is then just a matter of “pouring off” the gasoline. Chemists perform this operation somewhat more elegantly with a piece of glassware called a separatory funnel, which simply consists of a cone-shaped flask with a rotating valve at the bottom. Fill the separatory funnel about one-fourth full with water, making sure the stopcock is closed so no liquid flows out the bottom of the funnel.”

The others have similar descriptions – the technique is basically as I theorized (I did move into the social sciences because I didn’t enjoy organic chemistry). 

schematron.org/separatory-funnel-diagram.htm

The technology really isn’t a lot different than the settling bowls on the old tractors I used as a kid.  We have the power to restore purity in our gas tanks.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s