The FTIR spectra of the biochar samples were obtained using
diffuse reflectance FTIR spectroscopy. The biochars were ground
to 0.1 and 0.5 mg of each sample was placed onto the Ge window
of a Nicolet 5700 FTIR with an attenuated total reflectance attachment
(OMNI Sampler Nexus). Spectra were obtained over 256
scans with a KBr beam splitter, set at a resolution of 4 cm1, ranging
from 4500 to 650 cm1 and with an aperture size of 34 cm. The
reflectance was measured and analyzed using OMNIC v7.1 with
Happ–Genzel apodization and Mertz phase correction