hi friends,,, i need your guidance on following problem:

we are facing problem of "Foaming of glycerine during distillation."

process : Crude glycerine ( glycerine content 40 % ) is taken -- 10 % water is added to it -- 4 % cocentrated h2so4 is added ----

after some time 2 layers seperation is obtained.... titrate the glycerine layer out ...10 % dilute solution of Naoh (caustic) is added 25 % weight of glycerine layer. This neutralises glycerine layer to ph 5 - 6.

normal distillation to seperate out methanol from glycerine. foaming is observed.

That is normal,I've seen the same thing you need to have more head space in your distillation unit. That helped me out.
or do some version of the GL push pull method Add the scrubbers as shown

thanx chad,

do you mean that a foaming trap be used to overcome the foaming problem. is it effective?

shriyans

one more thing... would using sodium methoxide instead of Naoh (neutralizing glycerine)help in overcoming foaming problem

I don't think the catalyst has anything to do with it,We use sodium Methlylate and get the same thing,
I feel its the soaps and excess lye in the glyc thats doing it.

i tried neutralizing acidified glycerine layer. Made a solution of NaoCh3 ( sodium methoxide)
( 5gm Nao added to 100 mil of methanol) and added it to the glycerine layer.

what i found is a murky solution of glycerine and methanol. (in thick form) the ph was around 6.

kindly guide why this is happening.

Reducing your heat will help !
As for WHY its happening .I don't know its the nature of the beast.

chad,

thanx for your help, over acidification was the problem.

shriyans

YW.....

how much agitation is used during the distillation? is it possible to reduce the agitation?

-dkenny