I have a residue of 2kl in which 1.8kl is solvent (EDC) and rest material is residue. First i was thinking to go with normal distillation to recover our solvent. But i heared somewhere that there is some kind of RESIN by which if it got passes solvent will be pass only and residue will collect on another side of that resin. if there is any concept like this please help me. or there is any other to do?
2 Answers
Dichlorethane has a boiling point of about 84°C - If I would have to separate EDC from a product / residue, I would use a rotovap with water bath configuration. This distillation is a very gentle way to separate solvents from product / residue.
Set the temperature of the water bath slightly higher than the boiling point of the EDC.
If you want to get fancy to make your solvent super pure again after the rotovap distillation, you could perform a fractional distillation on it - however in most cases I think this might not be necessary.
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$\begingroup$ sir. if there is any way other than distillation. like any RESIN by which i can pass it through and it got separate. $\endgroup$ Commented Jan 19, 2018 at 10:43
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$\begingroup$ That will depend on the natural of the residue. Is it acidic? Polar? Non-polar? $\endgroup$ Commented Jan 19, 2018 at 14:24
Distillation is the way to go. Especially if you have to do it on industrial scale (if we have understood well, you have 2000 L to process). Normally it yields recovered solvent with low level of impurities. The operation is easy to perform and there are many installations available to do it.
Resins are not an option unless the only impurities in the solvent are acidic or basic, and preferably strong ones. Then you can use ion exchange resins. Otherwise the situation is just on the reverse side of what you want to do. Since your impurities are soluble in an apolar solvent, they are apolar too. There are resins for adsorbing these kinds of compounds, but then they must be in a polar solvent. Usually water is the option because even in alcohols the impurities do not get adsorbed. At least not completely.
If your impurities are not very apolar, they might be adsorbed on silica, but it is not likely that all of them will do so and probably none will do it completely.
Further, there is the economic aspect. Resins and silica are much more expensive than energy, so distillation is always preferred unless unfeasible. Moreover, for using adsorbents, the most efficient is to have them in a column with specific dimensions and a well designed bottom plate. Since the adsorption is an equilibrium, working in a column reduces the residual impurities much more. Unfortunately, these kind of installation are much less common than distillation units.
If you do not have such an installation yourself, it is quite easy to externalize the operation to some contract manufacturing unit.