Solvent Recovery -- Biggest Concerns and Questions?

Hi everyone,

I just want to pose the questions to everyone: when making a decision about how to deal with solvent recovery what are the largest concerns (i.e. energy consumption, safety, equipment life-time, scientific basis for equipment)?

Moreover, as extraction artists, it seems that scientific understanding of the principles of momentum, heat and mass transfer are becoming more and more attractive, and taking up more off-time…so, what are the biggest unanswered questions regarding these things?

In other words, what are the gaps of knowledge that have been the hardest to fill in regards to mass, momentum and heat balance?



The solvents I use in the refinement process are really only good to recover for me as cleaning agents. Generally I rely on the relative purity of fresh solvent maybe more than most. Nearly all process that I use end up being multiple solvents combined. Then of course water gets sucked up by the generally polar solvents and except for methanol form an azeotrope with about all the solvents on the polar scale. Purging water sucks.

As you know even hexane and methanol that I use in combination form an azeotrope when boiling and they are not even miscible in each other (mostly lolz). The problem becomes the time involved with dealing with this instead of just evapping off for cleaner instead of pure solvent recovery. I know a few tricks like the hexane methanol azeotrope can be dealt with using water but this all takes time and actually achieving pure solvent again, say methanol at 99.95% purity as stated on the label is really outside the scope of my ability or desire.

So for me solvent recovery is a weighing of the complexity involved with purifying it against the convenience of just repurposing the stuff for cleaner (always needed around this stuff) that is a mix of solvents and water and such. I always repurpose what I can and have no concerns about evaporating off the solvents generally in open air or in front of my blower into open air. Safety is always a concern but not whether to recover or not. Purity of the recovery possible without much fuss is the deciding factor.

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