Direct activation and hydrophobic modification of biomass-derived hierarchical porous carbon for toluene adsorption under high humidity

Abstract

Hierarchical porous starch-based carbon (PSC) with tunable pore structure (surface area 1974 ∼ 2721 m2/g and pore volume 0.80 ∼ 1.74 cm3/g) was prepared through direct activation. Due to its high surface area and large pore volume, PSC shows great potential for volatile organic compounds (VOCs) removal. Water vapor commonly exists along with VOCs and the competitive adsorption between VOCs and water vapor would significantly restrict the VOCs adsorption of PSC under high humidity. To address this issue, hydrophobic porous starch-based carbon composite (PSCC) was also prepared by physically mixing PSC with poly-divinylbenzene (PDVB) for toluene adsorption under high humidity to suppress the influence of water vapor. As relative humidity increased from 0 % to 80 %, the toluene adsorption capacity of PSC-2 decreased by 46 % while PSCC only experienced a decrease of 22 %. PSCC could also maintain its toluene adsorption performance (close to 100 %) after five adsorption–desorption cycles. Theoretical computations were also proved that the addition of PDVB inhibits water vapor adsorption and promotes its desorption, thereby enhancing the toluene adsorption of PSCC under high humidity. This work provides a controllable preparation and facile modification of porous carbon to improve its toluene adsorption under high humidity, offering a great application prospect for VOCs removal.