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Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: flaminang on January 27, 2007, 01:56:19 PM

Title: Separation of 10% methanol - 90% water mixture
Post by: flaminang on January 27, 2007, 01:56:19 PM

Hi guys,

I am new to this industry. I am curremtly doing a project to best separate a mixture of 10% methanol and 90% water (wt %). I am thinking of either reverse osmosis or vacuum distillation. After some research online, I am faced with contradicting facts. It says that RO can achieve a max of 20% separation and that VD is costly to maintain and space consuming.

Could anyone please shed some light on the separation effectiveness of RO. And advise which is the more suitable method if I were to do this on a large scale.

Thanks a lot.

Regards 

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: eugenedakin on March 22, 2007, 08:59:26 AM

Hello flaminang,

This is the first time that I have heard of separating a methanol/water mixture by reverse osmosis.  When you mention a 'max of 20% separation' does this mean a beginning mixture of 50:50 methanol:water will have a output of 100% methanol, but the other output tube (from the RO unit) will have a mixture of 20:80 methanol:water, or does it become a 10:90 methanol:water mixture (50% x 20/100 = 0.10 or 10% methanol)?

If the 10:90 mixture is attainable, then could you re-feed the 10:90 mixture back into the feed pipe of the RO unit to separate more methanol from the stream?

Just a thought.

Cheers,

Eugene

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: eugenedakin on April 06, 2007, 11:16:23 PM

Hello flaminang,

I REMEMBER!!!!

You can seperate methanol and water with acetic acid!!!!!  It was a while since I have done this (about 20 years ago) .

Try the seperation with various concentrations of acetic acid in the laboratory...

Cheers,

Eugene

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: technologist on April 07, 2007, 12:01:46 AM

Dear Eugene
The purpose of sep'n has to be the economic recovery of methanol.
Recovering it using acetic acid will lead to greater losses of Methanol + Acetic Acid in terms of Money Value due to higher cost of Acetic acid than Methanol.

So I wont favor it. Its OK for lab testing or Academics.

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: eugenedakin on April 07, 2007, 02:05:09 AM

Hi technologist,

No problem at all.. its all good.

I used it when there were 10,000 gallon tanks in a methanol plant.  Acetic acid was also created in the process, so it was very inexpensive.  Adding/implementing any other process had much more labor/capital/cost involved. 

It worked here economically, but I am not sure of the specifics of the plant you are working with.

I wish you the best.

Cheers,

Eugene

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: technologist on July 18, 2007, 02:27:26 AM

Use Hexyl Acetate to recover Methanol very Economically.
It doesnt dissolve in water and have very good affinity for Alcohols.

Let me know your results.
Thanks
Pawan

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: AWK on July 18, 2007, 02:33:29 AM

Methanol and water do not form an azeotrope. This mean a fractional distillation
gives a very clean separation.

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: eugenedakin on July 18, 2007, 07:26:15 PM

Thanks technologist...

 :)

Eugene

Title: Re: Separation of 10% methanol - 90% water mixture
Post by: bhaskaran on July 21, 2007, 08:19:15 AM

to my knowledge hexyl acetate to take methanol may not work.Best is going by distillation