High removal of volatile organic compounds on hierarchical carbons prepared from agro-industrial waste of banana fruit production for air decontamination

Activated carbons were prepared from residues from agro-industrial banana production (banana pseudostem) and evaluated in the capture of five different volatile organic compounds (VOCs): dichloromethane, chloroform, ethyl acetate, hexane, and cyclohexane. The biomass was first submitted to a hydrothermal treatment in the presence of KOH or ZnCl 2 as activating agents, followed by a dry pyrolysis. This new advance in methodology contributes to producing activated carbons with hierarchical porosity and high surface areas (701–1312 m 2 g −1 ), promoting increased interest in managing waste from banana fruit agricultural production. VOC capture studies were performed by thermal analysis, and capture capacities were similar to or higher than those presented in the literature. Higher adsorption capacities were related to the amount of available micropores, and the capture capacity was enhanced by the contribution of small mesopores. As the highest adsorbed amounts of dichloromethane (933 mg g −1 at 25 °C) were obtained for the material activated with ZnCl 2 (1:3), further studies were carried out for this system. The experimental data was fitted using a pseudo-first-order kinetic model. A study was carried out in different atmospheres (He, N 2 , air), showing that co-adsorption is occurring. Under simulated environmental conditions, the capture capacity decreased slightly at equilibrium, and the new adsorbent was used for up to ten cycles without significantly losing its efficiency, indicating good application in the field.