This study evaluated the properties of banana pseudo-stem (BPS) biochar derived from two different types of pyrolysis. The fast pyrolysis experiment was performed using a worktable-scale fluidized-bed reactor, while a bench-scale fixed-bed reactor was used in the slow pyrolysis experiment. The preliminary analysis shows that the feedstock contains 80.6 db wt% of volatile matter, 12.5 db wt% of ash and 33.6% of carbon content. Biochar yield reduces as the pyrolysis temperature elevates for both pyrolysis experiments. Fast pyrolysis yields a higher percentage of biochar (40.3%) than biochar yield obtained from the slow pyrolysis experiment (34.9 wt%) at a similar temperature of 500 °C. The evaluation of biochar derived at 500 °C shows that the biochar obtained from the slow pyrolysis process has higher carbon content, heating value, and surface area with lower ash content. Meanwhile, FESEM images show significant differences in surface morphology and the number of pores for biochar derived from fast and slow pyrolysis. These findings indicate the potential and suitability of BPS biochar derived from the slow pyrolysis process in applications such as soil amelioration and solid biofuel.
One of the world's challenging energy issues is introducing practical and affordable technology for organosulfur removal in fuel. Adsorptive desulfurization (ADS) can address this issue if highly effective activated carbon (AC) derived from industrial waste with excellent textural properties is used. In this study, the derived ACs from glycerin pitch loaded with P and Fe (AC/P and AC/Fe) were used as adsorbents for the ADS of model fuel oils, such as dibenzothiophene (DBT) at mild operating conditions. Under the optimized experimental conditions, 0.3 g of adsorbent dosage, 60 min reaction time, 30 °C temperature, and pH 4, the maximal DBT removal of 96.28 and 43.64%, respectively, for AC/P and AC/Fe was realized. The results indicated that the phosphorus-doped AC/P increases the selectivity of the ADS mechanism for DBT removal. Kinetic investigations disclosed that the adsorption process follows second-pseudo-order kinetics and the Langmuir adsorption isotherm model. The adsorbents remained active for five successive reuses, indicating their robust real-world applications. The electrochemical properties of the fabricated carbon electrodes were analyzed via cyclic voltammetry by coating the ACs with polytetrafluoroethylene (PTFE) as a binder. The transition-metal-doped AC/Fe, though exhibiting 5 times lower surface area, showed the highest specific capacitance at a scan rate of 5 mVs-1 (0.65 μF cm-2). Similarly, the extended AC:PTFE capacitor at a 10% binder ratio offered the maximum capacitance value (1.13 μF cm-2). The synthesized ACs demonstrated potential application as an electrode material, and hence glycerin pitch could be a low-cost precursor to improve the feasibility of commercial production of AC.