Background: Porous carbon materials are promising candidate supports for various applications.
Different approaches have been applied for preparation of various types of porous carbon
materials which in the most of them; disordered structures as well as relatively broad pore size distribution
are obtained. The most reliable method for preparing of the ordered carbon mesoporous is
nano-casting using mesoporous silicas as a hard template. However one of the challenges in the
nano-casting preparation is the mother silica template usually produced from expensive initial ingredients,
complicated and consuming process. Therefore, in the present work, the synthesis of the ordered
silica mesoporous using commercial water glass as the silica source is reported in which the
silicic acid has been prepared using cation-exchange resin. Furthermore, the adsorption properties
and phenolic compounds removal capability of the templated carbon mesoporous were compared
with the mesoporous carbon prepared by SBA-15 and activated carbon.
Method: The structural order and textural properties of the materials have been evaluated by
SAXRD (Small Angle X-Ray Diffraction), SEM (Scanning Electron Microscopy), TEM (Transmission
Electron Microscopy) and nitrogen adsorption–desorption analysis. Finally, the adsorption of
phenolic compounds on the carbon mesoporous has been studied.
Results: From SAXRD patterns it was deduced that the silicic acid amount has a considerable effect
on the final order of the mesostructure. Also, the nitrogen adsorption-desorption isotherms of different
silica samples represent Type IV isotherms. The formation of well-oredered hexagonal (P6mm)
arrays of mesopores could be clearly observed from SEM and TEM micrographs. Moreover, the
carbon templated from the optimized mesoporous silica revealed the well-ordered mesostructure
along with type IV adsorption isotherm confirming the nanoporous carbon has been successfully
templated. The microstructural images show the almost similar structure of the mother silica template.
In addition, EDS analysis of the silica and carbon templated sample confirms the almost elimination
of sodium. Finally, the performance the nanoporous carbon materials for phenolic compounds
removal was investigated. It is noteworthy that the adsorption capacity and equilibrium point in the
case of the prepared nanoporous carbon materials is very close to that of obtained for carbon prepared
by SBA-15. Furthermore the results showed the mesoporous carbon samples exhibit considerably
much higher adsorption capability in comparison to commercial activated carbon. Finally the
kinetic evaluation indicates that the phenolic compounds adsorption is accordance to the pseudosecond-
order kinetic model over the entire adsorption time.
Conclusion: The impurity-free and well-ordered hexagonal mesoporous silica particles have been
successfully synthesized by commercial water-glass using cation exchange resin. The resultant silica
has high surface area (778.3 m2/g), pore volume (1.1 cm3 /g) and pore size (6.1 nm), completely
comparable to mesoporous silica (SBA-15) produced by TEOS as a silica source. Moreover, the
carbon nanoporous templated by the prepared mesoporous silica has a well ordered structure, high
surface area (1033.9m2/g) and pore volume (1.08 cm3/g). Finally the results showed the prepared
mesoporous carbon could be considered as a suitable candidate for phenolic compounds removal
from water and waste water, as well. Furthermore, the experimental results also showed that the adsorption
process and equilibrium data were well fitted by pseudo second-order kinetic.