[sharp3502]

I have a mineral oil suspended in a water / surfactant solution in a glass container.

My objective is to use a surfactant that will "lift" the mineral oil off of the glass, or prevent it from sticking.
The mineral oil is a ferrofluid soution and I am interacting with it using magnets, so it can get "pressed" against the container and sticks.

The surfactant must not dissolve or break down the mineral oil at all.
The water / surfactant solution must be clear.

I would prefer something non-toxic, and easy to obtain.

I have tried anti-freeze(ethelyne-gylcol), and it worked somewhat, but not good enough.
I tried 50/50 isopropyle alcohol and distilled water. It worked a little, then disolved the oil.
I tried Dawn dish soap / distilled water , and it worked VERY well, but disolved the oil.
I tried fabric softener(Cationic surfactants) / distilled water , and it didnt work at all.
I tried a 100% solution of propelyne glycol, but it is too thick and I think worked more as a wetting agent than a surfactant(odd results).
I tried a 50/50 solution of propelyne glycol and distilled water, but the oil still sticks to the glass.

I have done some research on the different types of surfactants, but I can only get so far with my limited chemistry knowledge.
I would appreciate any suggestions, or at least pointing me in the right direction.
Do I need to focus on a particular type of surfactant? or combination?

I am not a chemist, so I apologize for any errors in my statements, feel free to correct me (doing the best I can with what I have).

Thanks

[fledarmus]

You've picked a tough job for a surfactant. Most surfactants work because they have one part of the molecule that can interact with water and another that can interact with oils. "Dissolving the oils" is what they do.

You might want to switch to either a coated glass or to a container made from a different material. Another possibility would be to change the polarity of the glass by washing it before you use it either with a basic or acidic solution, depending on the properties of the ferrofluid.

[Vargouille]

If I remember correctly, one process for making the ferrofluid was oleic acid and kerosene in addition to the magnetite, with oleic acid acting as the surfactant and kerosene as a "solvent", for lack of a better word.

[sharp3502]

You've picked a tough job for a surfactant. Most surfactants work because they have one part of the molecule that can interact with water and another that can interact with oils. "Dissolving the oils" is what they do.

You might want to switch to either a coated glass or to a container made from a different material. Another possibility would be to change the polarity of the glass by washing it before you use it either with a basic or acidic solution, depending on the properties of the ferrofluid.

The ferrofluid is a light hydrocarbon mineral oil, so that would be non-polar right?  The glass should be polar and hydrophilic by nature and I'm not sure how you would go about making it "more" polar, or finding another material that is more polar than glass.  The only thing that I have found is to use "Piranha" solution -sulfuric acid (H2SO4) and hydrogen peroxide (H2O2)- to hydroxylate the glass, but that sounds rather dangerous.

Should I forget surfactants altogether?  Perhaps there is another method to achieve my goal?  Something that would bond to glass so much that the oil wouldn't get a chance to? 

Thanks for your help, I guess I'm just grasping for straws now.

[fledarmus]

You've picked a tough job for a surfactant. Most surfactants work because they have one part of the molecule that can interact with water and another that can interact with oils. "Dissolving the oils" is what they do.

You might want to switch to either a coated glass or to a container made from a different material. Another possibility would be to change the polarity of the glass by washing it before you use it either with a basic or acidic solution, depending on the properties of the ferrofluid.

The ferrofluid is a light hydrocarbon mineral oil, so that would be non-polar right?

Right, but the light hydrocarbon mineral oil isn't the only component, is it? Otherwise it wouldn't exactly be a ferrofluid.

The glass should be polar and hydrophilic by nature and I'm not sure how you would go about making it "more" polar, or finding another material that is more polar than glass.  The only thing that I have found is to use "Piranha" solution -sulfuric acid (H2SO4) and hydrogen peroxide (H2O2)- to hydroxylate the glass, but that sounds rather dangerous.

yes, the glass should be polar and hydrophilic. It also has a pH memory - if the last thing that was put in the glass was acidic, the glass will be slightly acidic, and if the last thing put in was basic, the glass will be slightly basic. Depending on the constituents of your ferrofluid, it might make a difference whether the glass is acidic or basic for your application

Should I forget surfactants altogether?

You are already using surfactants to get your magnetic particles to dissolve in the oil. This may, in fact, be part of your problem. Surfactants allow charged particles and hydrophilic materials to be dissolved in non-polar solvents, and vice versa. The same interactions that keep your particles dissolved in the oil will make the oil stick to the glass. At best, you are going to be walking a tightrope between keeping your particles solubilized and keeping the oil from dissolving in the water. Choice and exact proportions of surfactants are going to be important to solving your problem, if you can solve it at all. 

Perhaps there is another method to achieve my goal?  Something that would bond to glass so much that the oil wouldn't get a chance to?

This is why I suggested modifying the glass to a plastic. You might be able to magnetically move the oil around better on a non-polar surface in a polar fluid than on a polar surface in a polar fluid. Just a guess, no real science behind that one. Just thought it might be worth the attempt. 

Thanks for your help, I guess I'm just grasping for straws now.

Best of luck - post videos if you get something to work!