I got two different results on surface of the same sample
1. BET Surface area (linear regression)
2. Langmuir Surface area (non-linear regression)
But which one is more correct for porous material?
BET SA is considered to be a widely accepted result for publications. Two different results are subjected to methods used for mathematical calculations in these methods, which are different. In this particular case, the SA is very low for BET calculation, which is almost non-porous. You may provide both the data in the final paper in the sure BET surface area XX (Langmuir Surface Area YY), the format and results are accepted. In another case, you may perform CO2@195K to understand the porosity of the material. I hope this may help you.
Imp Ref: Article Are you using the right probe molecules for assessing the te...
The Langmuir isotherm and Henry's equation for calculations. BET characteristic is applied in standards and technology.
Best regards,
When observing the 2 graphs it appears that the BET one fits well.
The Langmuir one usually recommanded for monolayer adsorption is not taking in to account porous distribution all over the surface area on the solid material.
Both methods are models and some assumptions are made. It is difficult or impossible to get results that are "right". It is therefore most important to report run parameters in all reports including degassing procedures.
Dear Mouthe Anombogo Ghislain Arnaud, thanks for your insightful suggestion.
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