Environmental Engineering Reference
In-Depth Information
TABLE 1.5
Techniques for Characterization of Pores in Carbon Materials.
Characterization Technique
Comments (advantages and disadvantages)
Adsorption/desorption of N 2 gas at
77K
BET method
Give overall surface area (SS).
Alpha plot
Give microporous and external SSs separately.
Give micropore volume.
BJH method
Differentiate microporous and mesoporous
SSs and volumes.
Give pore size distribution in mesopore range.
DFT method
Give pore size distribution in a wide range of
size.
HK method etc.
Give pore size distribution
Adsorption/desorption isotherm of
various gases (H 2 , He, CO 2 , CO, etc.)
Give the information of molecular sieving per-
formance.
X-ray small-angle scattering
Detect micropores, both open and closed pores
Transmission electron microscopy
Detect nano-sized pores, even less than 0.4 nm
size.
Give localized of information, need statistical
analysis of data
Scanning tunneling microscopy
Detect only pore entrances on the surface.
Give morphological information of the pore
entrance.
Need statistical analysis with criteria.
Scanning electron microscopy
Detect only macropores.
Mercury porosimetry
Detect mostly macropores
Difficult to apply for fragile materials
BET and the Dubinin models (DRS, DA) beside HK and DFT models are
widely thought to adequately describe the adsorption process of carbon nano ad-
sorbents. For convenience, the BET equation is normally expressed in the form,
which requires a linear relationship between p/p 0 , and model parameters from
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