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Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: Freshtone on February 09, 2018, 01:18:06 AM

Title: Addition of Bisulfite to Sodium Hydroxide
Post by: Freshtone on February 09, 2018, 01:18:06 AM
In a 3 phase distillation process of Lye there is introduced bisulfite. After many hours spent trying to find information online about the possible reason this could be for i have come to no conclusion. Im wondering if anyone knows the reason why adding bisulfite to lye production is necessary and if so why is it done?

Thank you in advance !
Title: Re: Addition of Bisulfite to Sodium Hydroxide
Post by: chenbeier on February 10, 2018, 12:57:18 AM
I dont understand where is a destillation process for lye. Lye is at least NaOH or KOH . Can you decribe more in detail what you are doing where you add the bisulfite. Bisulfite normaly reacts with aldehydes or is used as reduction compound.
Title: Re: Addition of Bisulfite to Sodium Hydroxide
Post by: Freshtone on February 11, 2018, 11:48:04 PM
Ah thank you for the reply! i can try to be a little more specific.

There is a 3 stage destillation process where you increase the concentration of NaOH up to 50% from 32%. The bisulfite is added before the first stage in a Falling film evaporator. Again this is all the info i have currently but my question really is more general. Why would you add Sodium bisulfite to NaOH ?

I read somewhere that it removes oxygen so as to decrease the corrosion in the system but again very vague. Some also says it reduces the amount of chlorine?

Any information really is helpful hehe :)

cheers !
Title: Re: Addition of Bisulfite to Sodium Hydroxide
Post by: chenbeier on February 12, 2018, 07:57:56 AM
This sounds strange to me. To increase the concentration of NaOH you boil it and the water will evaporate. There is no need to add something like bisulfite. Also by adding it, you contaminate the NaOH. To react with chlorine maybe is possible if the source is an Chlorine-alkaline elctrolysis. But then you have chloride and sulfate as contamination.
Title: Re: Addition of Bisulfite to Sodium Hydroxide
Post by: Freshtone on February 12, 2018, 09:56:15 PM
Thank you for the information. Ill have to look a little deeper into this and see what its all about, but thank you for the help :) Appreciate it !

Cheers !
Title: Re: Addition of Bisulfite to Sodium Hydroxide
Post by: adson on September 16, 2018, 05:23:06 AM
Bisulfite can be used as defoamer. As in case of boiling of NaOH since its a solution of soapy nature, there are chances of formation of foam, which will hinder the rate of heat transfer. Adding bisulfite will reduce the foaming tendency.