Powders of different biomass subjected to BET analysis for surface area and porosity analysis. which is the best way to understand the data and explain it ?
BET analysis results can interpere according to the BET, D-R, t-, BJH methods and BDTT isotherm classification.
BET, D-R and Temkin for adsorption ( lower P/Po values selection) data BJH for desorption data, also hysteresis and isotherms predictions to know the your materials belongings.
Without any treatment like carbonization and activation biomasses are rather low in surface areas, usually in the rage of 8-20 m2/g. Porosity is almost abscent. But with proper carbonization you can reach rather high surface areas.
There is a good reference
"Catalysis Science and technology -Volume 2. See chapter 4, "Texture of catalysts".
The standard approach for surface area measurement is to use the BET equation, taking care to use data points in the appropriate P/Po range. Briefly this means "good" linearity, an a positive intercept of the BET plot (which is reflected in a positive C-constant value). The complete adsorption/desorption isotherm can be used to evaluate micropore* and mesopore volumes and areas by employing a variety of calculation models (some already mentioned by other respondents). A good place to start would be the new IUPAC recommendations, available as full (and free to download) pdf from the De Gruyte (publisher) website: http://www.degruyter.com/view/j/pac.ahead-of-print/pac-2014-1117/pac-2014-1117.xml
*Un-carbonized biomass is unlikely to contain any micropores.
If you have commercial apparatus for making the gas sorption measurements, the user manual probably has enough information regarding theory and data reduction to get you started. If you need further advice, contact the manufacturer of said equipment. There are some good reference books (Lowell et al, Rouqerol et al) out there which will be of use to you. Particular authors to "google" would be Matthias Thommes, K.S.W "Ken" Sing or any of the other authors of the IUPAC publication referenced above.
Simply, u can compare your curve with the standard 6 types, calculate some parameters as pore volume, pore diameter, and void fraction
you may refer to the following article for the equations:
http://www.worldscientific.com/doi/abs/10.1142/S1793292012500385
Hi All,
I want to calculate the specific surface area of PVP/WO3 nanofibers that are deposited on aluminum foil. As these fibers contain polymer content too So i cant peel off them and want to analyze their surface area while they are on Aluminum foil. But the resulted area will also include the surface area of aluminum foil. How can i know the surface area of nanofibers only.
Thanks
Had once the same problem. The gas cannot differ between foil and fibers. Maybe you can try an infurect way. Try to measure first the foil only and then the whole sample. I dont think the foil has a high porosity but the weight will affect rhe results if given as m2 per gram sample.
Hi all, can anyone help me to analyze my ads-des plot and BJH plot for TiO2 and ZrO2 NCs. I am a bit confused about whether my sample is type III or type IV and in BJH plot only small hump peaks observed for TiO2 and there is no high intense peak. Similarly in the ZrO2 BJH plot, I am seeing broad peak with high intensity. Can anyone help me analyze? Thanks, advance
Are the values on y-axis the derivative and not the cumulative volumes? And are the units A or nm? If you use cumulative values they should increase against smaller pores.
I think the y axis values are derivatives and the units are in nm. How to use cumulative values? They gave only dVp/ddp.
I cannot say how to get the cumulative volume because I don't know Bels software. Try to use raw data (p/p0 and gas volume) and do the calculations in Excel.
@Henrik Romar, Is my adsorption-desorption plot for TiO2 and ZrO2 NCs were belong to Type IV isotherm or Type III isotherm. Please share your views. Thank you
up to me it is not a Type 3, there is still a small hysterisis loop. I added one of my own TiO2 runs and they are rather similar. At page 13 you can find the BJH analysis
I used the interpretation service of "Analyzetest.com" website for interpreting BET results and I was satisfied with the service provided
https://www.analyzetest.com/2021/03/14/interpretation-and-analysis-of-bet-results/
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