Multilayer Graphene Oxide Supported ZIF-8 for Efficient Removal of Copper Ions

HIGHLIGHTS: A multilayer graphene based adsorbent was prepared by a simple method; Adsorbents have high adsorption capacity and a high specific surface area; The multilayer structure of graphene layer provides a framework for ZIF, adding more adsorption sites. ABSTRACT: To address the performance deterioration of ZIF-8 for the adsorption of copper ions caused by powder volume pressure and particle aggregation, we employed multilayer graphene oxide (MGO) as a support to prepare composite adsorbents (MGO@ZIF-8) by using the in situ growth of ZIF-8 on MGO. Due to a good interfacial compatibility and affinity between ZIF-8 and graphene nanosheets, the MGO@ZIF-8 was successfully prepared. The optimal Cu(2+) adsorption conditions of MGO@ZIF-8 were obtained through single factor experiments and orthogonal experiments. Surprisingly, the Cu(2+) adsorption capacity was significantly improved by the integration of MGO and ZIF-8, and the maximum Cu(2+) adsorption capacity of MGO@ZIF-8 reached 431.63 mg/g under the optimal adsorption conditions. Furthermore, the kinetic fitting and isotherm curve fitting confirmed that the adsorption law of Cu(2+) by MGO@ZIF-8 was the pseudo-second-order kinetic model and the Langmuir isotherm model, which indicated that the process of Cu(2+) adsorption was monolayer chemisorption. This work provides a new approach for designing and constructing ZIF-8 composites, and also offers an efficient means for the removal of heavy metals.