[askrieg]

Good afternoon.

I am a senior chemical engineering student and several of us were given the task to design and build a batch distillation setup with a 6 foot glass column (w/ sieve trays). The lab manager wants us to include an experiment with colorful components so that future students will be able to see colorful separations inside the glass column. This doesn't seem like a reasonable expectation to me, as every distillation I can think of would just result in colorless distillate. We've been doing bench-top distillations on a ternary mixture of water, ethylene glycol, and diethylene glycol (anti-freeze) under vacuum since the proprietary inhibitors give it its bright green-yellow color. As expected, the colorful components do not come off with the water or ethylene glycol distillate.




The only distillations I've ever done that result in colored distillates were due to gaseous degradation products (e.g. NOx, Chlorine gas) but this is not desirable as if the students reused the mixture the impurities would accumulate.

A chemist contact at DOW suggested something today with algal biodiesel, but again, I'm not confident that it's distillate would be anything but colorless. I was wondering if anyone here had any ideas.