Self-assembly of MOFs-like materials by Zn2+ and histidine functionalized graphene quantum dots for the efficient removal of VOCs simulants

Abstract

Volatile organic compounds (VOCs) in the field of printing and packaging, have caused great harm to the environment. Therefore, the removal of volatile organic compounds (VOCs) is a hot topic, and metal-organic frameworks (MOFs) and graphene quantum dots (GQDs) have been applied in this field. However, improving the removal efficiency of different VOCs by using the two kinds of materials is still a great challenge. Herein, ZIF-8 like materials of Zn-His-GQDs were prepared by assembling Zn2+ and histidine functionalized GQDs (His-GQDs) in this work. The morphologies, structure and adsorption performances of Zn-His-GQDs were investigated. These results showed that mesoporous Zn-His-GQDs with a specific surface area of 63.3 m2·g−1 had similar structure to ZIF-8. When the content of Zn-His-GQDs was 200 mg, the equilibrium adsorption capacity for toluene solution of 500 mg·L−1 and ethyl acetate solution of 1600 mg·L−1 was 350 mg·L−1 and 669.44 mg·L−1, respectively. Due to channel filling, cation-π interaction, π-π interaction, hydrogen bond and high surface energy, Zn-His-GQDs exhibited a relative high removal efficiency for high concentration of toluene and ethyl acetate. The removal rate of Zn-His-GQDs on toluene and ethyl acetate after five cycles remained 59.80 % and 36.75 %, respectively. Moreover, this kind of MOFs like materials maintained stable structure during the adsorption in different pH solutions. Therefore, as-prepared Zn-His-GQDs with excellent adsorption performances for typical VOCs simulants in this work have potential application in the treatment of VOCs in the field of printing and packaging.