Simple construction of the α-MnO2@ZIF-8 nanomaterial with highly enhanced U(VI) adsorption performance and assessed removal mechanism

Abstract

In this study, the one-dimensional nanomaterial α-MnO2@ZIF-8 was satisfactorily fabricated using a simple hydrothermal method by modifying ZIF-8 on α-MnO2 nanowires for high-performance extraction of U(VI) out of water solution. The experimental data indicated that the adsorption of U(VI) on α-MnO2@ZIF-8 was intensely dependent on solution pH but not on ionic strength. The maximum adsorption of U(VI) on α-MnO2@ZIF-8 at pH ​= ​5.0 and T ​= ​298 ​K was 802.36 ​mg/g, substantially higher than the adsorption on α-MnO2(22.32 ​mg/g) or ZIF-8(551.31 ​mg/g) under the same conditions, indicating that the performance of the modified α-MnO2 was greatly enhanced. Attaining adsorption equilibrium within 45 ​min, the analytical kinetic process of α-MnO2@ZIF-8 indicated that its adsorption on U(VI) was monolayer chemisorption. The adsorption experiments and XPS analyzed the possible adsorption mechanism of U(VI) in the reaction with α-MnO2@ZIF-8 during the adsorption process, namely intra-sphere surface complexation, chemisorption and electrostatic interaction. The simple preparation and high removal efficiency of α-MnO2@ZIF-8 indicated that this adsorbent had good prospects for application in wastewater.