I am currently using n-Hexane to defat a protein powder we are making. Up until now, everything has been fairly small scale, and I have not worried about recovering the hexane solvent. However, we are now at the point where we need to process a 50 liter batch for small scale production, and I need to figure out how to recycle the hexane solvent. It will have dissolved fats which I do not care about.
I am thinking a distillation setup would be appropriate, but I have never made one this big before. Can anyone advise on exactly what I need to do this? Is it really as easy as a 2 stainless pots and a big Liebig condensor, or are there other things I need to factor into this design? In particular, hexane is rather flammable, so I don't want to do something dangerous.
Also, how far can I run the distillation? As I distill out the hexane, I am going to get a progressively more concentrated solute. I want to be as efficient as I can, but at some point I am going to get hexane dissolved in fat rather than fat dissolved in hexane. And as I crank up the heat to keep it liquid, I'm not sure where I should stop.
I don't need the hexane to be completely pure, because I am just going to reuse it again in the next defatting cycle, but I do need the process to be reliable and repeatable.
Does anyone have any recommendations on how to accomplish this?
i think destilation would be fine : Large round bottom flask (i think there is as large as 20L) + a large condenser and of course a suitable heating mantle.
and regarding where you should stop, i think you have to eyeball it, you should stop when then recovery flow is relatively very low. then evaporate the rest of hexaneat room temperature.
alternativaly: maybe you can avoid all the trouble of distilation to obtain the product, just by precipitating it out of the hexane solution. then proceed with the distilation of hexane just to use it in another run.
As Mr. Oussama suggested, distillation will work well and is easy to operate when you are dealing with a large batch, with less concern regarding the final purity of the product. An easier way to identify when to stop is by considering the initial concentration impurity in your Hexane solution which won't be consistent as you will proceed with the later runs. So you need to keep an eye every time to define when to stop the process.
I will highly recommend you to perform distillation after the initial precipitation of the protein in your solution. This will allow you to have a consistent impurity concentration at the beginning of each run and therefore will give nearly repeatable results.
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