90
6 Applications of Carbon Nanostructures Produced in Molten Salts
The adsorption capability of these 3D graphene nanosheets was evaluated and
compared with that of natural graphite powder with a BET surface area of around
18 m
2 g
−1 . For this, the adsorbents were added into 500 ml solutions containing
methyl orange (MO, 50 mg l
−1 ) and shaken at 20 °C. The SEM morphology of the
3D graphene saturated with MO (Fig. 6.7d–f) demonstrates that the morphology
of graphene nanosheets did not considerably change upon the dye adsorption. The
morphological stability of the 3D graphene maintained even after the thermal regeneration of the 3D graphene material at 300 °C, as confirmed by the SEM micrographs
shown in Fig. 6.7g–i. The stability of the 3D graphene nanosheets over the whole
adsorption and thermal regeneration process is remarkable.
The thermal stability of the molten salt-produced 3D graphene material can
be realized from the DSC and TG thermograms recorded in an airflow rate of
100 ml min
−1 , exhibited in Fig. 6.8. The TG thermogram shows that the material is stable until about 500 °C without an obvious weight loss. A major weight
loss can be detected from the TG curve which is accompanied by an exothermic
peak with the onset and peak temperatures at about 500 °C and 580 °C, respectively.
This event is assigned to the oxidation of the graphene material. Figure 6.8 clearly
confirms that the graphene material is thermally stable at temperatures below 500 °C
in air. The possible structural evolution of the molten salt-produced graphene over
the MO adsorption (50 mg l
−1 ) and thermal regeneration at 300 °C can be realized
from Raman spectra of Fig. 6.9.
Three distinct bands can be identified in the Raman spectra of Fig. 6.9; D
(~1360 cm
−1 ), G (~1580 cm
−1 ) and 2D (~2720 cm
−1 ). The G-band is related to
Fig. 6.8 TG-DSC thermograms of the 3D graphene nanosheets, recorded at a heating rate of
10 °C min −1 under an air flow rate of 100 ml min −1 , reproduced from Ref. [98], copyright 2019,
with permission from Elsevier
6 Applications of Carbon Nanostructures Produced in Molten Salts
The adsorption capability of these 3D graphene nanosheets was evaluated and
compared with that of natural graphite powder with a BET surface area of around
18 m
2 g
−1 . For this, the adsorbents were added into 500 ml solutions containing
methyl orange (MO, 50 mg l
−1 ) and shaken at 20 °C. The SEM morphology of the
3D graphene saturated with MO (Fig. 6.7d–f) demonstrates that the morphology
of graphene nanosheets did not considerably change upon the dye adsorption. The
morphological stability of the 3D graphene maintained even after the thermal regeneration of the 3D graphene material at 300 °C, as confirmed by the SEM micrographs
shown in Fig. 6.7g–i. The stability of the 3D graphene nanosheets over the whole
adsorption and thermal regeneration process is remarkable.
The thermal stability of the molten salt-produced 3D graphene material can
be realized from the DSC and TG thermograms recorded in an airflow rate of
100 ml min
−1 , exhibited in Fig. 6.8. The TG thermogram shows that the material is stable until about 500 °C without an obvious weight loss. A major weight
loss can be detected from the TG curve which is accompanied by an exothermic
peak with the onset and peak temperatures at about 500 °C and 580 °C, respectively.
This event is assigned to the oxidation of the graphene material. Figure 6.8 clearly
confirms that the graphene material is thermally stable at temperatures below 500 °C
in air. The possible structural evolution of the molten salt-produced graphene over
the MO adsorption (50 mg l
−1 ) and thermal regeneration at 300 °C can be realized
from Raman spectra of Fig. 6.9.
Three distinct bands can be identified in the Raman spectra of Fig. 6.9; D
(~1360 cm
−1 ), G (~1580 cm
−1 ) and 2D (~2720 cm
−1 ). The G-band is related to
Fig. 6.8 TG-DSC thermograms of the 3D graphene nanosheets, recorded at a heating rate of
10 °C min −1 under an air flow rate of 100 ml min −1 , reproduced from Ref. [98], copyright 2019,
with permission from Elsevier