A porous activated carbon derived from banana peel by hydrothermal activation two-step methods

Abstract

Activated carbon from biomass is often the best choice for use as an environmentally friendly supercapacitor material. This study aims to identify the effect of hydrothermal (HT) treatment on the structure and specific surface area (SSA) of activated carbon made from banana peels. The carbon was activated through two stages of HT and physical activation without KOH. HT was carried out at a temperature of 200°C with a holding time of 2 or 6 hours. The hydrocarbon was then activated in the second stage using nitrogen gas at a temperature of 700°C for 1 hour with a flow rate of 100 mL/min. In the treatment process without HT, two stages of activation, variations of activators (water, H3PO4, and PEG6000), water volume ratio, and holding time were studied. SSA was measured using the Brunauer–Emmett–Teller adsorption method. X-ray crystallography was used to identify the crystal structure and the surface morphology of activated carbon was observed using FE-SEM. The results showed that the activation method and process conditions greatly affected the SSA of activated carbon. HT activation resulted in SSA of 476.9 m2/g. The degree of crystallization of activated carbon enhanced the HT effect. The spherical structure of activated carbon was formed when H3PO4 was added, while the layered structure was formed when PEG6000 was used. Overall, the two-step activation preceded by HT process with the addition of H3PO4 resulted in activated carbon with better SSA and carbon structure and has the potential to be used in a wide range of applications such as electrode supercapacitors.