Source :
Science of The Total Environment
Descriptors :
CO2 specific surface area , Porosity , BET specific surface area , Pore volume
Abstract :
The surface area and pore volume of carbonaceousmaterials,which are commonly determined by N2 and/or CO2
gas-physisorption, are important parameterswhen describing environmental processes such as adsorption. Their
measurement requires prior degassing of samples, which can change the nature of the material. Current guidelines
for biochar characterization recommend different degassing temperatures. To investigate how degassing
temperatures affect gas-physisorption we systematically degassed a range of materials (four biochars, carbon
nanotubes, and Al2O3 reference material) at different temperatures (105, 150, 200, 250 and 300 °C; for ≥14 h
each). Degassing temperatures had no effect on Al2O3 or carbon nanotubes but the measured surface areas and
pore volumes of biochars increased by up to 300% with degassing temperature. An equation is presented for
predicting surface area obtained at different degassing temperatures. Elemental analysis and results from sorption
batch experiments suggest that surface area and pore volumemay increase as biochar components volatilize
during degassing. Our results showed that degassing temperatures changematerial properties and influence gasphysisorptionmeasurements,
and therefore need to be standardized. These resultsmay also apply to the characterization
of other complex materials, including carbon nanotubes coatedwith natural organic matter and fouled
activated carbon.
Title of Article :
Biochar total surface area and total pore volume determined by N 2 and CO 2 physisorption are strongly influenced by degassing temperature
Author/Authors :
Sigmund, Gabriel , Hüffer, Thorsten , Hofmann, Thilo , Kah, Melanie
Author/Authors - جزئيات :
