Sciencemadness Discussion Board

Removing Ethanol from Gasoline

joseph6355 - 11-5-2018 at 21:19

Gasoline where I live contains up to 15% Ethanol.
I was wondering if it would be possible to remove this Ethanol from the Gasoline and leave it relatively pure.

Would washing the gasoline mixture with water remove the traces of Ethanol?
Water is miscible with Ethanol but not with Gasoline.

j_sum1 - 11-5-2018 at 22:45

There's all sorts in gasoline that will mix with water at least partially. (You want to taste water that has collected in your gas tank?) Using brine might get a cleaner extraction.

But no, it won't be pure. There's detergents to contend with as well. And then you also have the task of distilling and concentrating the ethanol. I can't see that it would be worth it. You are better to start with vodka.

joseph6355 - 12-5-2018 at 00:32

Quote: Originally posted by j_sum1  
There's all sorts in gasoline that will mix with water at least partially. (You want to taste water that has collected in your gas tank?) Using brine might get a cleaner extraction.

But no, it won't be pure. There's detergents to contend with as well. And then you also have the task of distilling and concentrating the ethanol. I can't see that it would be worth it. You are better to start with vodka.

You got it wrong. I want the Gasoline, not the Ethanol. The Ethanol will be discarded.
The objective is to remove as much impurities from the Gasoline as possible.

I can get it without the additives (it's the cheapest one).
But would Ethanol dissolve in water if it was already mixed with Gasoline? I wanted to know if Ethanol would separate out.

12thealchemist - 12-5-2018 at 01:08

Since you're after the gasoline itself, washing with water thoroughly would remove any alcohols like ethanol and isopropanol that are present, and probably any traces of detergent. However, it would be worth bearing in mind the potential for emulsions to form if detergent is present.
You could then dry the washed gasoline over some sort of drying agent like anhydrous calcium chloride or magnesium sulphate. The former would also help remove any traces of alcohols left by complexing with them.
The remaining traces of water and the could be removed by using sodium-magnesium oxide aggregate (made by igniting a mixture of magnesium and sodium hydroxide) as promoted by NurdRage over on YouTube. The only question here is if other components in the gasoline that have not been removed would also react and cause problems? Gasoline covers a relatively wide range of mixtures within boundary concentrations.

joseph6355 - 12-5-2018 at 01:34

Quote: Originally posted by 12thealchemist  
Since you're after the gasoline itself, washing with water thoroughly would remove any alcohols like ethanol and isopropanol that are present, and probably any traces of detergent. However, it would be worth bearing in mind the potential for emulsions to form if detergent is present.
You could then dry the washed gasoline over some sort of drying agent like anhydrous calcium chloride or magnesium sulphate. The former would also help remove any traces of alcohols left by complexing with them.
The remaining traces of water and the could be removed by using sodium-magnesium oxide aggregate (made by igniting a mixture of magnesium and sodium hydroxide) as promoted by NurdRage over on YouTube. The only question here is if other components in the gasoline that have not been removed would also react and cause problems? Gasoline covers a relatively wide range of mixtures within boundary concentrations.

That's what I thought. I was going to wash it several times with water and then dry it with magnesium sulphate.
Gasoline is made of Isooctane, Butane and ethyltoluene, mainly.

Short question, can I dry hydrated magnesium sulphate but heating it?

12thealchemist - 12-5-2018 at 01:36

Yes, practically all common drying agents can be dried/dehydrated simply by heating them. It's partly why they are used as drying agents.

unionised - 12-5-2018 at 13:01

Don't forget to make sure you have removed all the flammable materials before trying to dry it.
Also even if you remove ethanol, gasoline is giong to be a mixture of chemicals- it's hard to define "pure" gasoline.

DavidJR - 12-5-2018 at 18:05

Quote: Originally posted by joseph6355  

Short question, can I dry hydrated magnesium sulphate but heating it?


I dried a whole load of magnesium sulphate last night.

All you need to do is put it in a baking tray, say at most 10mm deep layer, and bake in the oven. Stir it up and break up big clumps periodically, otherwise you'll end up with one massive hard lump at the end. I'd start at 150C for a couple of hours then up it to 200+ C for another hour or so - if you heat too quickly it can dissolve in its water of crystallization, which again, will leave you with a difficult to deal with lump at the end.

If it's perfectly dry you will get a very fine powder.

joseph6355 - 13-5-2018 at 00:15

Quote: Originally posted by unionised  
Don't forget to make sure you have removed all the flammable materials before trying to dry it.
Also even if you remove ethanol, gasoline is giong to be a mixture of chemicals- it's hard to define "pure" gasoline.

I'm trying to get what is called "white gasoline" to extract Polybutene from a rubber-based commercial product.
It needs to be anhydrous and free from all crap that I can possibly remove. Its either this or then buy a 1 liter bottle of n-Heptane that costs too much to be worth it, so I'd rather pay around 1.2 usd for 1 Liter of Gasoline and try to purify it. I don't need it 100% pure analytical grade, I'll use it as a solvent that will be latter evaporated from the final product.
Quote: Originally posted by DavidJR  
Quote: Originally posted by joseph6355  

Short question, can I dry hydrated magnesium sulphate but heating it?


I dried a whole load of magnesium sulphate last night.

All you need to do is put it in a baking tray, say at most 10mm deep layer, and bake in the oven. Stir it up and break up big clumps periodically, otherwise you'll end up with one massive hard lump at the end. I'd start at 150C for a couple of hours then up it to 200+ C for another hour or so - if you heat too quickly it can dissolve in its water of crystallization, which again, will leave you with a difficult to deal with lump at the end.

If it's perfectly dry you will get a very fine powder.


I used to do that with ammonium nitrate for ANFO-based explosives. Nice to know that I can reuse my drying agents.
Is there a limit for how many times I can recycle it?

[Edited on 13/5/18 by joseph6355]

unionised - 13-5-2018 at 00:41

Have you considered zippo fuel?

XeonTheMGPony - 13-5-2018 at 04:35

you can recycle it indefinably, providing you remove contaminants.

Microwave drying is fast and efficient for Magnesium Sulfate.

Fractional distillation with precise temp control, collect every thing from 30c - 60c, you can recover the butane and other such LB material using crushed ice and salt in your condenser water if you wish.

DavidJR - 13-5-2018 at 08:06

Quote: Originally posted by joseph6355  

Nice to know that I can reuse my drying agents.
Is there a limit for how many times I can recycle it?
Quote: Originally posted by XeonTheMGPony  
you can recycle it indefinably, providing you remove contaminants.


Just be sure to allow any residual flammable hydrocarbons to evaporate in a well-ventilated area before you bake it.