Role of chemical pre-treatment in the development of super-high surface areas and heteroatom fixation in activated carbons prepared from bagasse

This study examined the role of low temperature chemical treatment, using sulfuric acid prior to activation, in developing high surface area and fixation of sulfur functional groups in activated carbons from bagasse. Activated carbons exhibiting super-high surface areas (∼2700 m2/g) and highly microporous solids (4.5–11.6 Å) were developed from bagasse as a result of chemical pre-treatment. Thermally stable sulfur groups (CS, SS and SO) were also effectively fixed onto the carbon using the same acid treatment. Thermally stable nitrogen groups (NO and NO2), from nitrogen originally present in bagasse, were also found in the activated carbon generated in this study. The role of chemical treatment was investigated by examining bagasse degradation during carbonization and the development of carbon texture and surface chemistry as a result of this treatment. In situ synchrotron based X-ray diffraction was used in monitoring the re-ordering of micrographitic structure in the activated carbons during carbonization and activation. The re-orientation of the micrographites was found to be an essential factor in the development of super-high surface area carbons. The carbon surface chemistry was established from measured surface acidity, heteroatom concentrations and surface functional groups analysis by Fourier transform infrared spectroscopy (FTIR). The acid treatment was shown to be an effective method in imparting surface chemistry on the carbons generated from bagasse.