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Triethylene Glycol (TEG) pH too high - remedy?

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BobHawker:
Hi everyone,

I represent a trading company that supplies TEG to oil & gas companies for gas dehydration purpose.

Our last delivery has problems in that the enduser reported that they were reading 8.1 pH for rich glycol and 9.7 for lean glycol which exceeded their target range.

They then tested the pH which we supplied which comes out at pH 8.4 and they claim that this exceeds our specification of 6.0-8.0

If the the 8.4 TEG is returned to us, is there any method to reduce the pH to below 8.0?

Please bear in mind that I'm not from chemistry background, thank you for any advice offered.

Arkcon:
First of all, you'll want to verify their results.  They could be wrong.

Second of all, what are your specifications?  If you really guarantee no more than 8.0, didn't you check first before shipping?  How do you test?

What else in in your triethylene glycol?  Does you supplier need to do a better job of purifying it?  Or did your company make it?  What do your engineers and chemists say?

The pH of a non-aqueous solution is, at best, a little dicey -- sort of a hit or miss result depending on the method used.  At worst, totally invalid, but on some levels this is a personal point of view.  At any rate, you may want to titrate to determine exactly how much alkali is there.  You'll want a chemist for this, and also to decide how to best neutralize the product and still have it work.  Although I'd bet re-purification would work best.

BobHawker:
Hi Arkcon,

Thank you very much for your reply.

The pH reading of 8.4 by client was correct as we just did a sample testing by a 3rd party lab (SGS) which verified the result.

You are correct in that we should have the TEG pH tested before being shipped out from manufacturer. We will request a pH test from manufacturer before shipping out for future purchases.

Our problem now is we will have about 300+ drums of TEG with pH of 8.4 which is not acceptable to client and I don't think the supplier would be willing to take back the stock.

The client accepts delivery in tote tanks in which we do decanting from the drums into the tanks using pumps. 

Is it possible to mix say 1/2 a tank of pH 8.4 TEG with 1/2 a tank of pH 6.8 TEG (from another TEG supplier) to get TEG of pH 7.6?

Would that be worth trying out?

curiouscat:
Did you do a full assay of your TEG? Is there moisture / water in it?


--- Quote ---The pH reading of 8.4 by client was correct as we just did a sample testing by a 3rd party lab (SGS) which verified the result.

--- End quote ---

Can you post the assay procedure used by the 3rd party lab?

curiouscat:
Is there an additive? MEA / DEA etc? Did your supplier add too much of it?

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