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[Propacket]

Can anybody help me get the antoine constants for 50%MDEA and 99.75%TEG .

[MrShorty]

What resources do have access to and have looked at? Perry's may have vapor pressure data for TEG, I know DIPPR has it (though they use the Riedel equation rather than the Antoine equation). There are other vapor pressure compilations out there that have been published in book form (Ohe is one, Boublik, Fried, and Hala have published another). The textbook The Properties of Liquids and Gases has a database in the appendix with vapor pressure correlations. I've seen spreadsheets floating around the internet (there used to be one somewhere on this site) that had put some of the information from the 3rd edition of this book (3rd edition is from the '70's so it won't have the latest and greatest information, but maybe adequate for your purposes). You could also try NIST's website (webbook.nist.gov) and see if those compounds are listed their.

The only other thing I would note is that we don't usually model vapor pressures of mixtures with the Antoine equation. 99.75% TEG is essentially pure, so that one will be fine. Normally for mixtures, we use a more robust VLE model (for example, using the NRTL or Wilson activity coefficient equation to model the liquid phase and obtain the partial pressure of each component). I suppose it depends on exactly what you are trying to do, but, to do it more rigorously, you're going to probably want to review your VLE equations/modeling to get the pressure over a 50% MDEA (other 50% water, I assume) mixture.