isopropyl alcohol filter
 

I'm looking for some ideas from you guys. I'm in the process of building a kind of automated parts washer which uses isopropyl alcohol as it's only solvent. The system works on a volume principal, very similar to a dishwasher, and has a sump system, very similar to an aquarium. The sump will have a mechanical filter to remove larger particular but because it's not pressurized the fluid relies on gravity alone to be forced through the media so it is limited. The alcohol will eventually become contaminated with small particles and oil. The volume of the system will be between 5 and 10 gallons, I'm aiming for as little as possible.

What I'm currently working on is a way to extend the life of the alcohol to reduce cost and of course environmental impact. So besides distillation anyone got any ideas on a filtration system? The system will be separate and filter the alcohol when the parts washer is not in use, as required. I would like to still use the same pump which is a Panworld 250PS-F, max head 45ft, max flow 1900gph.

Got a old cannister filter hanging around? you could use it a both a supply pump and filter.

probably going to need a little more than that. Main concern is removing the oil and other dissolved containment.

Why alcohol? wont the evap. rate be really high? Going to be tough to remove the oil I would think as it would be totally mixed with the Alc.

We have some man made fiber "mats" at work that will pick up oil and not water. Made for oil spills to clean up the environment. I don't know what it would do with the alcohol, but maybe persue something along those lines.
I have one of those mats at home, but do not have isopropanol. Otherwise I would test it out for you

We have to use alcohol in preparation for strain gauge mounting (transducers). The washer and sump system are completely sealed and vented together. After the washing cycle the sump connections are sealed and the loss through evaporation is small.

Similar to "adsorb-it"? Do you know where you source it? I'd be interested in trying it but yeah I'm uncertain how it will work with the alcohol since it actually dissolves the oil unlike water.

For the mats you can get them at CE franklin, Midfield or and oilfield supply store there are mats that will only adhere to hydrocarbons so it will strip the oil out. There a also socks that do the same thing they only absorb oil water will pass right through.

Cool! I'll source some tomorrow and try them out. In the mean time more ideas please :biggrin:

I've heard of people using sand filters to remove oil efficiently, any experience?

Build a separator. As long as the particles are heavier then the alcohol they should drop out given the right conditions to do so. No mechanical filtration needed. Just let gravity do it's job and all you need is 2 baffles. Just have to size in correctly?

Will that work if the oil is dissolved? Doesn't this only work for sediment?

I never saw the oil part just the small particle part. So the oil will actually dissolve into the alcohol?

I'd have to ask my mgr, who's a solvent extraction specialist, but I suspect you're going to need to do some sort of solvent extraction or use a special media bed (same principle as in DI media).

I don't think you'll be able to just do a mass separation as you're having an attraction between the functional groups in the oil & alcohol.

You might contact Dow, Fisher or Anachemia to see what media they have that might be appropriate for your application.

you could always set up the filtration for after the wash, chemical r/o back into the tank and reuse. I would also think that sediment may also be your friend in this type of system, as it would offer some abrasiveness for scrubby bubbles

Yeap which is why it's used as a solvent.

Good info, thanks

That's kind of what I was thinking, a separate unit to filter the alcohol between washes as required. I've never heard of a chemical R/O before, could you elaborate? If it's anything like the water ro with a 4 to 1 waste ratio it would be much good. I can't invest in something that will only recover a small portion of the alcohol, it has to be the majority if not all.
Also the sediment won't be beneficial, the parts are actually pretty clean when they go in but there will be traces of grit from the sandblaster and oil from heat treating as well as whatever chemicals are used in the powder coating or plating processes. If any particles remain on the surface the gauging process could fail which is not good.

I ordered some oil absorbing mat which can be used to filter oil from water however I'm pretty sure it's not going to work. A little research shows the mat absorbs all hydrocarbons so water can obviously pass through because it's not a hydrocarbon but alcohol is a hydrocarbon so I think this experiment is already flawed.

OK so the mat is out, it absorbed the alcohol as well and the solution that did make it through contained the same amount of oil. Basically in this application it's just expensive cloth.

Prob have to use some solvent as mentioned, or some kinda flash tank. The alcohol should boil around 84 C but the oil would be much higher so you could prob separate them this way? Any reason why the parts washer can't run with warm-> hot alcohol?

Yeah fractional distillation would be the best way to reuse the alcohol but this is something I'd rather avoid. Our production staff are not the most careful people around and I don't mean to say they aren't smart but they have managed to do some pretty stupid things. The last thing I want is to add is highly flammable vapor into their routine, I'd much rather keep things simple and safe if possible. Also have to consider the cost of distilling, the energy required for the process is significant in comparison to the cost of the alcohol.

I don't want to heat up the alcohol in the washer either, this would not exactly be safe. I actually have a thermo switch installed which shuts the system down if the fluid gets too warm.

Soluble in water... so anyway you can mix it with water to lose the oil and then separate it from the water after?

... but getting it out of the water would prob involve heat too ahah

Solvent it is ahah

In soluble is salt solutions? So what would happen if you mixed it with water and then added salt ahah. The salt just wouldn't dissolve or it would dissolve and separate the alcohol?

So far we have add water, add salt... and it still prob won't work ahah

So you want me to add water to the alcohol? I'm not sure that will work, sounds like a headache.

You have to find something that takes oil out and leaves the alcohol. Or vice versa.
Not enough of a chemist to suggest any chemical.
But then again, thats why you are asking.
Maybe find a chemists forum.

[quote=hillegom;495133]You have to find something that takes oil out and leaves the alcohol. Or vice versa.
Not enough of a chemist to suggest any chemical.
But then again, thats why you are asking.
Maybe find a chemists forum.[/quote]

The company I work for produces chemicals that do that very thing, but the cost of them is far greater then IPA. IPA is a commodity chemical, anything designed to seperate oil and IPA is likely to be a specialty chemical and therefore that much more expensive. Your likely better just changing out your IPA when it gets to dirty. If your worried about the environmental aspect ( thank you for being so ) most disposal companies have outlets for this type of material, they will most likely resell it to a company that will consume it in process. I dispose of 1,000's of kg's of material a year and very little of it goes to incineration or down hole, I venture to say less then 1%.

The company I work for produces chemicals that do that very thing, but the cost of them is far greater then IPA. IPA is a commodity chemical, anything designed to seperate oil and IPA is likely to be a specialty chemical and therefore that much more expensive. Your likely better just changing out your IPA when it gets to dirty. If your worried about the environmental aspect ( thank you for being so ) most disposal companies have outlets for this type of material, they will most likely resell it to a company that will consume it in process. I dispose of 1,000's of kg's of material a year and very little of it goes to incineration or down hole, I venture to say less then 1%. [/quote]

If I had the isopropanol to dispose of, I would research a little more and maybe burn it in my car. I know you can add 10% methanol with your gasoline.