dear farid

I hope we have chance to get positive and reasonable answers from experts and researchers who report these high values of surface area for biochars!

thanks for your question. I'm pretty sure that it is impossible to have such higher surface area regarding the biochars . I hope we receive satisfactory answers.

I think it is practically impossible to have such a surface area for a biochar. Such a high surface area is obtained for activated carbon that were derived from either physical or chemical activation. Another thing that may have led to such a result might be a faulty readings from the surface area equipment.

Biochar cannot have such a high surface area because during the pyrolysis process, some of the pores created by the evolution of volatile matters are filled up with tarry materials and those pores are cleared up when the biochar is subjected to activation 

It all depends on the porosity and how the powder is compacted. Hence, you can produce thespecific surface area (m^2/gram) that you need regardless of the type (biochar, graphene, etc.)

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA

dear Oluwatosin Oginni

I completely agree with you regarding the surface area of biochar and it's derivates which are produced through the activation processes. But There is one thing in your comment about filling up the pores I noticed. I will appreciate it if  you send me an article that confirms the problem of filling the pores with the tarry material during pyrolysis in details

dear professor Yehia F. Khalil

actually, I'm just confused about higher amounts of surface areas that have been reported in some articles. it seems that these amounts aren't plausible and reasonable. I want to make sure amounts of the surface area obtained in our laboratory are exact or not?

anyway, thank you for your kind consideration of my questions.

Due to the article that I've uploaded it seems increasing KOH/C ratio (Potassium hydroxide as chemical activation agent) can enhance sample's surface area.Additionally, it has shown that the surface area in KOH/C=5 is the highest one and it reported about 2100 m2/g.Also, it has reported that "the characteristics of porous carbon adsorbents(related to textural Properties) can be varied by the use of carbon precursors and chemical and physical activation methods." but according to my experiences that were very strange results and I'm so interested in finding a way to give such a textural Properties.