As we study that modification/functionalization of any carbon material affect its surface area and pore volume. In literature, sometimes the surface area decreases while in some it increases. I want to know that why in some treatments the surface area decreases and vice versa.
Your guidance will be highly appreciated.
Regards,
Ayesha Gul
Dear all, in addition I would mention also importance of the modification method which typically includes using quite aggressive substances. These substances can change surface state in pores of the carbonaceous particles not only through grafting of functional groups but also due to deep oxidation of carbon, degradation of the surface and partial detachment/removal of the material. This can be a reason of increased surface after modification. However, if the detached material remains in pores it can decease their real surface. So it depends.
can you read this paper
Article The influence of carbon nanotubes and graphene oxide sheets ...
Hi
Determining the surface area is a calculation from the model, and in reality models may differ. Also of great importance (this is often neglected) is the value of sorption energy. There is still the effect of nitrogen condensation (if the sample is studied by nitrogen sorption) in micropores, which erroneously overestimates the real value of the surface area. It is not possible to actually measure the surface area of a porous body. In your case, I think the sorption energy affects, because near the surface groups the gas sorption will be different, but you can try to simulate this.
Best regards, Alexandr.
Dear Ayesha Gul, whatever the treatment is, always it imparts changes and arrengements of the sheets, which may be an increase or decrease in the physical properties such as the pososity and specific area. Introducing functional groups or spacers always manifest by having their own fingerprint and presence. My Regards
Thank you Abdelkader BOUAZIZ Aleksandr Nikolayevich Abdelkader Dehbi for your valuable answers.
Abdelkader BOUAZIZ i want to know if there is any decrease occur in surface area then it because of bonds arrangement owing to modifying agents? As our mission is to increase the surface area of absorbent following by active sites number and subsequently adsorption capacity. So, how can we justify it then?
Thank you,
Regards,
Ayesha Gul
Hi;
The specific surface area of carbon materials strongly depends on the type of functionalization and the size of the grafting molecule. In the case of small molecules, the grafting block some pores which make them inaccessible, which create a significant, decrease of the cumulated surface area and a noticeable difference of the pore size distribution. In the case of sterically hindered molecules, access to the pores is limited, which gives high specific surface area values.
With my best regards
Dear Ayesha Gul, there are two simple reason. First the modying agent once introduced it obviously occupiez a certain surface and volume, and also be considered as an obstacle to acceed to the neighborhood surface (hidden). Both reasons contribute to the réduction of specific area. This matter is well seen in clay chemical modification. My Regards
Dear Abdelkader BOUAZIZ Thank you for clarification.
Kind regards,
Ayesha Gul
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