loading unit in cm3(STP) about pygaps HOT 6 CLOSED

Hi NicHaaJun,

I believe you can do what you wish by using:

iso = pygaps.PointIsotherm(
     loading=[],
     pressure=[],
     loading_basis="molar",
     loading_unit="cm3(STP)",
)

Keep in mind, when reporting an isotherm on STP, pyGAPS is using a molar basis, since it's assuming ideal gas behaviour ( V[STP] = P/nRT ).

I hope I understood your question?

All the best,
Paul

from pygaps.

Hi Paul,

Yes that worked. Thank you for such a fast response!

I thought I could do:

iso = pygaps.PointIsotherm( loading=[], pressure=[], loading_basis="volume", loading_unit="cm3(STP)", )

I simply misunderstood.

Best,
Nicolai

from pygaps.

Hi Nicolai,

Yes, I can see it being a bit confusing. I made the choice based on what made sense from the programming side. I will consider highlighting this in the manual.

By the way, you can permanently convert the isotherms to "real" volume if you do something like:

iso.convert(loading_basis="volume", loading_unit="cm3")

I will close this now, if that's ok. Don't hesitate to contact me if you have any other questions.

-pi

from pygaps.

By the way @NicHaaJun , may I ask where you are from? I am always curious to hear how and where pyGAPS is used!
-pi

from pygaps.

Sure, I am a PhD student at the University of Oslo in the section of heterogeneous catalysis. Although I don't do extensive adsorption characterisation for my research (other than routine work) we have people in the group who do. For a long time commercial software has been used for this. But, being a python enthusiast and due to the never ending problem of commercial software licensing, I decided to build a simple interactive tool based on pyGAPS and ipywidgets for doing simple adsorption analysis. Many of us in the group do routine analysis work.

Btw I do have a question about how pyGAPS chooses the pressure range based on the roq rules. As I understand it you do not get an unambiguous answer but typically multiple and slightly different pressure range segments that qualify. So, how does pyGAPS choose from these ranges.

Again I really enjoy pyGAPS and I think it is a great initiativ!

/Nicolai

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I see, nice to make your acquaintance Nicolai, a new place on the map I can mark! Also, regarding your development of a GUI, that's a noble goal, and pretty much how pyGAPS started during my own PhD. Have you considered publishing and/or making it open source, it would be a boon for the community?

For the Rouquerol pressure range determination, I am using the classical rules as originally envisaged: (i) positive C constant, (ii) increasing region of Rouquerol plot and (iii) statistical monolayer location in chosen region. I am assuming that you have seen the recent paper from the group of David Fairen-Jimenez regarding their BETSI procedure which performs a multiple fitting routine in this region. This is a fantastic approach that is now possible with the "low cost" of computing power.

The difference is essentially either taking the whole applicable range (rouquerol) or the best consistent subset of that applicable range (betsi). This has the advantage of removing obvious outlier points which would not be detected by the original method and converging to a "best case" scenario automatically. A trained operator should spot these issues and tweak the method to make the same choices...but this is just wishful thinking. Hopefully one day this approach could also be implemented in pyGAPS.

-pi

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