Metal finishing Q&As since 1989

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Calculation of amount of Sodium Hydroxide to neutralise Citrisurf 8500

Hi

I work in the Pharmaceutical Industry as a service engineer and I am currently using Citrisurf 8500 to passivate my RO Tanks at company I work and we are pumping it 700kg of Citrisurf with 1700L of Water

I have to neutralise it using 40%w/v sodium hydroxide [affil links] to bring the pH to 7-10 before I can discharge it as per the regulations here.

Can you please show me the calculations that will bring my answer as to how much sodium Hydroxide I would use? I do not yet know the pH at which the Citrisurf solution is going to leave the tank at yet- but can we assume few pH for the sake of argument?

Help Urgently Wanted !

Aravind Srinivasan
Engineer - Sydney, Australia
February 18, 2011

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Aravind

Why not take a 500 ml sample, neutralize it in the lab, and extrapolate what you will need?

Willie Alexander
- Colorado Springs, Colorado
February 22, 2011

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As Mr. Anderson had mentioned, grab a sample and neutralize it with the NaOH you're going to be using.

For confirmation, you can use a pH probe or a by adding a few drops of phenolphthalein [on eBay & Amazon] indicator to the sample. Phenolphthalein turns a pinkish-purple color at a pH of 8.2, which is just about nominal for your discharge requirements.

We can't give you any tips on how to pre-calculate it, since nobody knows what the heck Citrisurf 8500 is, whether or not it has been diluted, or if it has degraded to any significance from the passivation process.

Cheers
RK

Robert H Kinner
- Toledo Ohio
February 28, 2011

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Aravind,
I assume you mean CitriSurf 8050. Please contact me directly, I do have this information.

Of course, Willie Alexander's suggestion is completely viable as well.

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois

March 1, 2011

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You can use hydroxide at the beginning and when almost neutralised go for sodium carbonate / washing soda [affil links]; even with excess you won't overshoot req. pH.
Good luck

Khair Shishani
aircraft maintenance - Al Ain, UAE
May 17, 2011