XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1249
the distribution of the biochar on the surface of the pins,
and for achieving high-quality SEM images. Brunaur-
Emmett-Teller (BET) was used to determine the biochars’
pore properties, N2 adsorption-desorption isotherm, and
the biochars’ pore size and surface area. Fourier Transform
Infrared Spectroscopy (FTIR) was used to expose the func-
tional groups present in these biochars, they are dried and
put in the desiccator to avoid moisture. Grounded pow-
ders of the biochar samples were pressed flat against the
diamond crystal surface of the FTIR, spectra were recorded
using the Digital FTS 7000/UMA 600 Fourier Transform
infra-red spectrometer, and the absorbance of each sample
was measured from 4000 to 400 cm–1 using 128 scans per
sample with a speed of 20kHz and a resolution of 4 cm–1.
The spectra were corrected using the surrounding air as
the background spectrum in the range of 7.8–8.2. FTIR
Results were analyzed using Varian resolution pro 640 soft-
ware (version 5.1, Agilent, Santa Clara, CA, USA).
RESULTS AND DISCUSSION
Characterization of Biochars Before Adsorption Tests
The zeta potential measurements of the three biochars
exhibited a downward trend with increasing pH levels, pos-
sibly due to the degree of protonation of the hydroxyl and
carboxyl groups present at each pH level (Figure 1). This
shows that the biochar carries a negative charge, the mag-
nitude of which significantly increases as the pH increases.
The values of the zeta potential for the three-biochar ranged
from –4mv to –43mv, which shows a wide range of negative
charges present on the surface of the biochars. With this
negative charge on the surface of the biochars, La (III) is
likely adsorbed on the surface via electrostatic attraction.
The BET analysis was used to determine the biochars’
surface area and pore size distribution. The surface areas
of SW (353m2/g) and AH (255.08m2/g) were significantly
higher compared to that of WCC (62.45m2/g). This can
be attributed to the high pyrolysis temperature and the
composition of the wood biomass at the time of produc-
tion. According to the BDDT and IUPAC classification
of pores (Thommes et al., 2015 Wang et al., 2012), the
77K N2 adsorption isotherms of SW, WCC, and AH were
all type II and IV isotherm curves. The biochar, which is
a mesoporous material, has pore diameters between 2 nm
to 50 nm, as seen in Table 2, and the amount of quantity
adsorbed increases with increasing relative pressure indicat-
ing the presence of mesopores which are likely to increase
with increasing temperature (Wang et al., 2013 Weimin-
Chen, 2015) as shown in Figure 2. It can also be observed
that adsorption began at low relative pressures, which may
imply the presence of micropores in the biochar surfaces
(Ramesh et al., 2014).
SEM was used to assess the morphology of the biochars
before lanthanum adsorption. Figure 4 shows that SW has
smooth surfaces, whereas WCC and AH had rough and
porous surfaces before lanthanum adsorption. These porous
and rough surfaces agreed with the BET results given in
Table 2, which showed AH had a higher pore volume than
-45
-35
-25
-15
-5
0 2 4 6 8 10 12
pH
SW
WCC
AH
Figure 1. Zeta potential measurement results of the three biochars
Zeta
potenti
(mV)
the distribution of the biochar on the surface of the pins,
and for achieving high-quality SEM images. Brunaur-
Emmett-Teller (BET) was used to determine the biochars’
pore properties, N2 adsorption-desorption isotherm, and
the biochars’ pore size and surface area. Fourier Transform
Infrared Spectroscopy (FTIR) was used to expose the func-
tional groups present in these biochars, they are dried and
put in the desiccator to avoid moisture. Grounded pow-
ders of the biochar samples were pressed flat against the
diamond crystal surface of the FTIR, spectra were recorded
using the Digital FTS 7000/UMA 600 Fourier Transform
infra-red spectrometer, and the absorbance of each sample
was measured from 4000 to 400 cm–1 using 128 scans per
sample with a speed of 20kHz and a resolution of 4 cm–1.
The spectra were corrected using the surrounding air as
the background spectrum in the range of 7.8–8.2. FTIR
Results were analyzed using Varian resolution pro 640 soft-
ware (version 5.1, Agilent, Santa Clara, CA, USA).
RESULTS AND DISCUSSION
Characterization of Biochars Before Adsorption Tests
The zeta potential measurements of the three biochars
exhibited a downward trend with increasing pH levels, pos-
sibly due to the degree of protonation of the hydroxyl and
carboxyl groups present at each pH level (Figure 1). This
shows that the biochar carries a negative charge, the mag-
nitude of which significantly increases as the pH increases.
The values of the zeta potential for the three-biochar ranged
from –4mv to –43mv, which shows a wide range of negative
charges present on the surface of the biochars. With this
negative charge on the surface of the biochars, La (III) is
likely adsorbed on the surface via electrostatic attraction.
The BET analysis was used to determine the biochars’
surface area and pore size distribution. The surface areas
of SW (353m2/g) and AH (255.08m2/g) were significantly
higher compared to that of WCC (62.45m2/g). This can
be attributed to the high pyrolysis temperature and the
composition of the wood biomass at the time of produc-
tion. According to the BDDT and IUPAC classification
of pores (Thommes et al., 2015 Wang et al., 2012), the
77K N2 adsorption isotherms of SW, WCC, and AH were
all type II and IV isotherm curves. The biochar, which is
a mesoporous material, has pore diameters between 2 nm
to 50 nm, as seen in Table 2, and the amount of quantity
adsorbed increases with increasing relative pressure indicat-
ing the presence of mesopores which are likely to increase
with increasing temperature (Wang et al., 2013 Weimin-
Chen, 2015) as shown in Figure 2. It can also be observed
that adsorption began at low relative pressures, which may
imply the presence of micropores in the biochar surfaces
(Ramesh et al., 2014).
SEM was used to assess the morphology of the biochars
before lanthanum adsorption. Figure 4 shows that SW has
smooth surfaces, whereas WCC and AH had rough and
porous surfaces before lanthanum adsorption. These porous
and rough surfaces agreed with the BET results given in
Table 2, which showed AH had a higher pore volume than
-45
-35
-25
-15
-5
0 2 4 6 8 10 12
pH
SW
WCC
AH
Figure 1. Zeta potential measurement results of the three biochars
Zeta
potenti
(mV)