Preparation of bimetallic Pb/Zn metal-organic framework @graphene oxide composite and its adsorption performance for Pb(II) and Zn(II)

Abstract

The removal of harmful heavy metals from water bodies has emerged as a major concern owing to ecological challenges and the associated threats and dangers they pose. In this study, we used graphene oxide (GO) as an adsorbent to absorb Zn2+ and Pb2+ in simulated wastewater. The Pb2+and Zn2+adsorbed on the surface of GO were utilized as metal ion centers, and benzene-1, 4-dicarboxylic acid (BDC) served as an organic linker to synthesize a bimetallic Pb/Zn-MOF@GO composite via the hydrothermal method. Pb/Zn-MOF@GO composite was characterized using SEM, XRD, FTIR and BET analytical methods. The Pb/Zn-MOF@GO shows a higher BET surface area of 460 m2 g-1 compared to that of Pb-MOF@GO (296 m2 g-1) and Zn-MOF@GO (408 m2 g-1). The maximum adsorption capacities of Pb/Zn-MOF@GO composite material for Zn2+ and Pb2+ were 114.68 and 132.62 mg L-1, respectively. The adsorption kinetics of the composite materials for Zn2+ and Pb2+ follow the pseudo-second order kinetic model, and the adsorption isotherm best fits the Langmuir model. The adsorption mechanism was governed by hydrogen bonding, and the -C=O reaction was also involved in the adsorption process. The findings of this study provide new insights into water pollution and resource utilization.