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separation: Naphtalene, Ethylene glycol, Ethyl benzene, Styrene
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ciel:
Hello,
Mol % in feed Boiling Melting Soluble in Soluble in Molecule point (C) Point (C) water benzene
Naphtalene 12 218 80.2 yes yes
Ethylene glycol 18 197 -11.5 yes no
Ethyl benzene 32 136.2 -95 no yes
Styrene 38 145.2 -30.6 no yes
Separate this into four essentially pure product streams. Indicate the separation technology you choose and the sequence of the separation steps.
The answer that I came up with :
N, EG, EB, S -EXTRACTION w/ water--> we get two streams which are :
the first stream : EB,S --DISTILLATION--> we get two streams, one contains EB and another contains S
the second stream : water + N + EG -EVAPORATION-> we get two streams, #1 is water and #2 is N + EG
Do EXTRACTION with benzene to the second stream which contains N,EG. The results are two streams, #1 contains EG and #2 is benzene + N.
My questions are :
* Is my answer correct?
The heuristic that I should follow are :
- if the feed is already in two phases, use a mechanical separation technology. If it's in single phase, first consider equilibrium-based separation
- for equilibrium-based separation, consider differences in boiling pt, melting pt, solubility in common solvents, and binding to solid surface
-avoid adding foreign material as possible
- remove corrosive/hazardous material early
- separate out components present in the greatest quantity first
- save difficult separations for last
-operate at temperatures and pressures as close to ambient as possible. Prefer T above ambient to below.
* How to separate benzene and naphtalene ? I don;t havae any idea how to answer this one.
That's all. Sorry if this post is very long. I really hope someone could help. Thanks.
Abing:
My questions are:
1.the T difference between EB and S is small, which makes distillation need much energy.
2.Make sure that there is no azeotropy of water and EG
The B.P. of bezene is 80.1??you can separate bezene and naphthalene by distillation easily
cap:
you can't separate benzene and naphtalene by distillation - naphtalen can't be in liquid phase
eugenedakin:
Hi Ciel,
There are many ways to skin-a-cat, or in this case to separate a mixture. Although the method I am proposing *should* work, it would be best to try it in the lab first....
I like your first idea of adding water ... this will cause the ethylene glycol to adhere with water, and since Ethyl benzene is soluble in alcohols, it should (?) separate with the EG. (You may get eg, h2o, EB, or you may just get eg and h2o). The water-glycol mixture can be separated by either 1) distillation or 2) centrifuge. The water-glycol-styrene mixture can be separated by distillation.
Abing is right about the close boiling points of Ethyl Benzene and Styrene for distillation ... it could be done, but at the expense of a large amount of energy.
Benzene has a BP of 80.1 C. Cap, why can't Naphthalene be in the liquid phase (I'm just curious)...
TTFN,
Eugene
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