[lawrencek]

I have some processes for purifying gasoline for use in Coleman lanterns.

The first stage is to remove the ethanol.
I rinse it with water and decant. The water at first contains large "bubbles" and is cloudy, but i do it several times. I am not worried about the large bubbles that remain, i just rinse and decant until the water is clear. I can discuss this process later.

Now i want to remove any water that remains in the gasoline.

I tried magnesium sulphate first and then silica gel, both dried in a microwave. The most promising was the silica gel. However it went into sulution in the gasoline, although it removed most of the water there is now a saturated solution of silica gel (and possibly any remaining water). If i evaporate the gasoline (leave it open to the air) I get a milky solution of the gel.

Is there any way of precipitating it? or is there any other way.

Gel is great because it can be regnerated by heating it or setting the gasoline and gel decanted on fire ready for use, but how can i get the gel out of the gasoline. it looks lovely and clear but even when filtered using coffee papers it still goes cloudy and will deposit the gel in the lamps.

I am thinking of using starch or flour instead - but will they remain in the gasoline?

What else can i do?

Lawrence

[Enthalpy]

Hi lawrencek!

Sorry this isn't exactly your question, but... Why shoudn't you burn some odour-free white spirit instead? It will be nicely pure and not as horribly flammable as gasoline. I've also had a decently cheap solvent containing "branched alkanes C₉ to C₁₁" that was hard to flame and odour-free hence nicely pure too.

Does the lamp have a wick? I haven't seen details.

With true cold (-50°C for instance) you can precipitate moisture from kerosene (gasoline too I suppose) and filter it out.

[billnotgatez]

@Enthalpy

Does the lamp have a wick?

Many Coleman lanterns have Gas mantles

[lawrencek]

Thanks. I'd like to continue the gasoline route as I have got most of it to work.

The SiGel does a nice job of drying but remains in the gasoline. It is saturated.

Can I use a micro filter membrane? I would think that the SiGel molecules are bigger than the gasoline or at least ionic or hydrophilic or something. I was thinking of something like the MrFunnel or at least a sheet of the stuff I could use like a filter paper. I could then recover the gel and dry it - I've got that bit to work.

What specification membrane?

Thanks

Lawrence

[Intanjir]

The silica gel isn't really dissolved, just suspended.
You could try some method to remove it or focus on not suspending it in the first place.
How well did you rinse your gel beforehand? It may come with a fair number of disconnected silica nanoparticles only loosely adhered to the gel.
Using a more cohesive grade of silica gel or changing how you pass the gasoline across the silica may help.
A column of sand should help remove remaining suspended silica.

[lawrencek]

I just used simple gel - sold by "Bob Martin" as cat litter. 10 KG for STG 4.50!.

I shook the stuff up, and had several goes with fresh gel - nice and easy, and I have a process for drying the gel which indeed had adsorbed water.

The gasoline appeared crystal clear, but when I put some on a shiny tray and blew across it it went milky cos the gel, saturated, precipitated. It did not look as if it was in suspension, more dissolved. Does even damp silica gel dissolve in gasoline - I would not have thought so. I was surprised to find some like I did.

A sand filter - a good idea. I am waiting to hear from the Mr Funnel people - what sort of filter material would you suggest?

Thanks

[Intanjir]

Silica hardly dissolves in anything. There would be negligible dissolution into gasoline especially.

Your cat litter probably contains something besides silica which is dissolving.
Rinsing it with enough gasoline should eventually remove the gasoline-soluble substance from the gel, but it might be better to just get pure silica gel.

[lawrencek]

So you think that the milky stuff could be something else dissolved in the gel.

Interesting - I noticed some white powder in the jugs I had the gasoline in, but it looked looked like gel. I can always test it to see if it behaves like gel and swells up with water again.

I wonder if I was the gel in water before using it to get the extra stuff out, whether I will lose much gel into the rinse water. I would not have thought so and will try that, then rinsing it with a tea strainer or fine sieve.

That sounds good to me and easy to try. I can always ask Bob Martins technical department what else is in there.

With the magnesium sulphate hexahydrate dried there were significant amounts, a sort of constant dissolving mixture since MgS04 is well soluble in the water I was trying to remove!

Lawrence

[lawrencek]

I have concluded that the white stuff was additives in the silica gel.
I have got some fresh gel and washed it in boiling water and the water was cloudy. Even rinsing with cold was the same.

I rinsed it under running water through a sieve, and now I have clear gel and clear water. I am going to leave it for a while and then try and then dry it in the microwave.

I am also going to evaporate some of my first batch of petrol (with the white precipitate) and see if the white powder will adsorb steam by this means I can see if it is silica gel trapped in solution with its water. (I don't see how  it can be, but it was with the MgS04.6H2O.

Thanks for your help - applying a scientific method to the project!

[lawrencek]

I have left the original "creamy" gasoline to evaporate. As it evaporates, the "cream" collects as water. I will wait to see what solid residue is left.

I think the additives in the Silica Gel dissolved in the gasoline's water and remained. The excess water was removed by the gel, leaving the additives in saturated solution. Any evaporation caused them to settle out as a fine milk initially. I assumed it was the Si-Gel as a powder - I do not think it is.

I think it will be easy to solve the problem - I'll let you know how I get on - the scientific method!