Adsorption recovery of chlorinated volatile organic compounds on coffee ground-based activated carbon of tunable porosity

Abstract

Chlorinated volatile organic compounds (CVOCs) play an indispensable role in industrial production, but meanwhile pose serious threats to human health. As a response to the urgent and challenging requirements of reducing pollution and carbon emissions, in this work, the critically favorable ultra-micropores and hierarchical porous structure are constructed onto the low-cost coffee ground-based activated carbon (AC) for the CVOCs adsorption recovery. To regulate the processes of carbonization and activation, the formation of the porosity is elaborated in terms of elements, functional groups and graphited structure. As expected, abundant ultra-micropores (<1 nm) are particularly apt to the adsorption of 1,2-dichloroethane (1,2-DCE) of small size and also contribute positively to the adsorption of chlorobenzene (CB). Moreover, the sample S400-4 possesses a large surface area (1643 m2/g), pore volume (0.89 cm3/g) and hierarchical porous structures that greatly benefit the adsorption of both 1,2-DCE (2.11 mmol/g) and CB (4.15 mmol/g). The advantage is ascribed to the facilitated transfer of CVOCs through the hierarchical porous structures and the higher affinity of CB for the π-π interaction. S400-4 presents a good performance in the recycle tests and with the interference of co-existing components alike, which indicates the engineering application potential of coffee ground-based AC. Hopefully, this work sheds light on the structure-function relationship between biomass-based AC and CVOCs adsorption, and contributes to the targeted development of suitable CVOCs adsorption materials and recovery technologies.