Properties of sago waste charcoal using hydrothermal and pyrolysis carbonization

The thermochemical biomass conversion has widely used because it is considered environmentally friendly and carried out at low temperatures and pressure to reduce costs. Hydrothermal and pyrolysis carbonization are two kinds of biomass conversion that widely practiced in the current time. In this study, hydrothermal and pyrolysis carbonization was carried out using sago wastes in bark and pith form. The purpose of this research was to compare the charcoal properties between chars from hydrothermal and pyrolysis carbonization. In this study, the carbonization process was conducted in two methods, i.e., hydrothermal and pyrolysis carbonization. The hydrothermal carbonization was performed with a temperature of 250 degrees C for 4 h, using rotary digester with water as a medium. While the pyrolysis carbonization was conducted with a temperature of 400 degrees C for 5 h, using a vacuum electrically heated tube as a reactor. The characterization of chars performed was proximate and elemental analysis; iodine number; calorific value; Fourier-transform infrared (FTIR); X-ray diffraction (XRD); scanning electron microscope (SEM); Brunauer, Emmett, and Teller (BET); and pyrolysis-gas chromatography-mass spectroscopy (Pyr-GC-MS). The results showed that the iodine adsorption capacity, surface area, and pore volume of chars from hydrothermal were higher than pyrolysis. In contrast, the calorific value of chars from pyrolysis was higher than the chars from hydrothermal. Based on results, chars from hydrothermal can be used as a precursor of activated charcoal specifically for adsorbent, while chars from pyrolysis are potential energy sources.