Energy and matter balance of process of activated carbon production from Algerian agricultural wastes: date palm rachis and jujube stones

This study investigated pyrolysis and activation of palm rachis and jujube stones at 1073 K to determine the yield of the detailed composition of the released gases, tar, condensable and solid material after each step of the process. The biomasses and their derived materials were characterized using approximate and ultimate analysis and calorimetry analysis in order to carry out the matter and the energy balance of both examined processes. Empirical assumptions were used to mine the collected data. Furthermore, wood was also used in this study for comparison purpose. The carbon weight percentage (%C) was 46.1, 49.3 and 49.2% for palm rachis, jujube stones and wood, respectively. This last parameter becomes 67.3, 91.7 and 87.0% for the same burn-off value (55%) for the activated carbons produced from the cited biomasses, respectively. The global matter balance of the solid materials recovered from the processes was 15.9, 11.6 and 12.5% for activated carbon (at 55% of burn-off) prepared from palm rachis, jujube stones and wood, respectively. The global energy balance was positive for all examined samples with the recovery of close to 70% of the energy initially contained in virgin biomass as combustible gases form. Finally, it was found that rachis palm and jujube stones are efficient as precursor for thermochemical conversion.