Langmuir Isotherm

The Langmuir adsorption model describes how the surface coverage depends on the pressure of the gas phase. These adsorption isotherms are different at different temperatures.

[@herrmanselcher1632]

Truly invaluable. Thank you!

[@adityaa8918]

Had this in one of my textbooks, was really not able to understand (apparently the author had made some mistakes in typing too). I could not find even a single video or another book which explained this concept at my level. You have done it sir Thank you

[@PhysicalChemistry]

I'm glad it was helpful for you

[@sla4214]

you are so professional !!

[@PhysicalChemistry]

Well, it is my profession, haha. But thanks, I appreciate that

[@zoe4662]

very grateful thank you

[@PhysicalChemistry]

Glad you found it useful

[@youssufalhaw2055]

thank you sir I really needed this

[@PhysicalChemistry]

You're welcome. I'm happy to help

[@RogerTerrill]

awesome vids... binging!

[@PhysicalChemistry]

Thanks. Pace yourself!

[@moayadsr5717]

Thank you.

[@PhysicalChemistry]

You're welcome

[@belal22001]

Thank you for the video. I know that the Langmuir isotherm can be used to fit in into experimental adsorption data. Can the experimental adsorption data be from the same experiment at different time points, or do the data need to be from different experiments where the initial adsorbate concentration varies?

[@somchoon]

At almost end of slide, this is a mistake. When T going up, the ratio of -E/RT going down and when -E/RT going down the exponential of the term (-E/RT) going up as it contain negative sign (not going down) you could compare exponent of e^(-1.5) = 0.22, while e^(-2.5) = 0.082 that mean when -E/RT going down , K (K=const.e^(-E/RT)) should be going up instead.

[@xinyueliu5498]

i wonder if p0 is a function of T, as saturated pressure also increases with temperature.

[@PhysicalChemistry]

No, P° in this equation is not the saturated vapor pressure (I use P* for that). Instead, P° represents standard pressure. (see the derivation here: kzbin.info/www/bejne/Z2i3aoiHqdVjjac) The choice of standard pressure sometimes varies (1 atm or 1 bar, for example), but it is not temperature dependent.

[@dannymenzies3115]

Great video, although confused about the influence of temperature. If T increases, -eps/kt decreases but the as this is a negative power of exponential, a lower power in 1/exp(eps/kt) will lead to a higher k and therefore theta surely?

[@PhysicalChemistry]

Remember that ε is negative. (It is the energy of the adsorbed molecule, which is lower than the energy (zero) when the molecule is in the gas phase.)

[@dannymenzies3115]

@@PhysicalChemistry thank you!

[@belal22001]

Hello my good sir, have you produced a video about using an isotherm for adsorption modelling, where it would be applicable for batch adsorption to leach heavy metals from water using a zeolite.

[@PhysicalChemistry]

My only videos on adsorption are about the fundamental models: Langmuir and BET. And about their origin and derivation and meaning. Their application in particular circumstances is left to you!

[@belal22001]

Yes sir of course, I just wanted to give context of my interest. Perhaps what I'm asking is, are these Langmuir videos you made applicable for my surface interaction? Or are they exclusive for gas adsorption.@@PhysicalChemistry

[@PhysicalChemistry]

@@belal22001 Langmuir model can be used for solution-phase adsorption. If the adsorption is reversible, non-cooperative, and occurs only in a monolayer, then there is a chance the model could work, even though it is a simple, idealized model. Here is a video with some more information on the limitations of the Langmuir model: kzbin.info/www/bejne/aYnLnHiYbt50qsU

[@shrishirol2206]

Thanks

[@PhysicalChemistry]

You're welcome

[@shrishirol2206]

@@PhysicalChemistry The closest statistical derivation of Langmuir Adsorption i came across was in the book, "The physical chemistry of Surfaces- 4th Edition" by Arthur W Adamson. This was way more easy and simple. I did teach the statistical derivation to my students and then promptly shared your KZbin channel. Cheers from India.

[@shrishirol2206]

@@stevenjstuart oh Sure, will check out

[@shrishirol2206]

By the way, do you have any suggestions for Surface area determination of solids by Harkins Jura Absolute method, Entropy method and Point B method. Thanks

[@shrishirol2206]

@@stevenjstuart Professor, by the way do you have book suggestions for the determination of surface area of Solids by Harkins Jura Absolute method, Entropy method and Point B method. Thanks in advance.