Resumen
Coconut shell was useless biomass and became waste from agriculture and food industries, however it can be used as raw material for activated carbon production. This is due to that its structure contained high carbon content. Temperature used in producing activated carbon was very high and led to the greater energy consumption. Therefore upgrading coconut shell by using Hydrothermal Carbonization (HTC) method to synthesis the hydrochar was performed in this study. Because the HTC was high potential technology which can be conducted at lower temperature than other thermochemical conversion technology. The purposes of this study was to investigate the suitable condition to produce the hydrochar using HTC technique by varying temperature, resident time, biomass size and biomass to water ratio. The physical and chemical properties of hydrochar were characterized using TGA, FTIR, HHV, SEM, Iodine number analyzer, Boehm titration and true density analyzer. The outcome from this study will provide the key parameters which are significant effects on valuable product from coconut shell. Parameters used for hydrochar production were the reaction temperature (120°C, 160°C, 200°C), reaction time (30 minutes, 2 hours), size of grinded coconut shell (1 mm and 0.425 mm) and grinded coconut shell to water content (1:5, and1:15).). The hydrochar yield decreased from 99.52% at 120°C to 59.24% at 200°C and the true density of hydrochar was between 1.41 to 1.37 g/cm3. The synthesis hydrochar were continue treated with hydrolysis, dehydration, decarboxylation, aromatization and recondensation reactions and it was found that the functional groups and surface structure of hydrochar were improved. However, hydrochar yield decreased from 59.24% at 30 minutes to 55.15% at 2 hours and true density of hydrochar was between 1.32 to 1.30 g/cm3. As a result, the reaction temperature was a vital parameter on the structure of hydrochar.