Siyi Wang,Yuxuan Bai,Zhixiong Zhang,Chengde Xie,Wenhui Song,Chen Wang,Zhuoyu Ji,Jianjun Wang
In this study, the one-dimensional nanomaterial α-MnO 2 @ZIF-8 was satisfactorily fabricated using a simple hydrothermal method by modifying ZIF-8 on α-MnO 2 nanowires for high-performance extraction of U(VI) out of water solution. The experimental data indicated that the adsorption of U(VI) on α-MnO 2 @ZIF-8 was intensely dependent on solution pH but not on ionic strength . The maximum adsorption of U(VI) on α-MnO 2 @ZIF-8 at pH = 5.0 and T = 298 K was 802.36 mg/g, substantially higher than the adsorption on α-MnO 2 (22.32 mg/g) or ZIF-8(551.31 mg/g) under the same conditions, indicating that the performance of the modified α-MnO 2 was greatly enhanced. Attaining adsorption equilibrium within 45 min, the analytical kinetic process of α-MnO 2 @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-MnO 2 @ZIF-8 during the adsorption process , namely intra-sphere surface complexation, chemisorption and electrostatic interaction . The simple preparation and high removal efficiency of α-MnO 2 @ZIF-8 indicated that this adsorbent had good prospects for application in wastewater.
Ming Zhong,Donghui Yang,Chenchao Xie,Zhang Zhang,Zhen Zhou,Xian-He Bu
Manganese oxides (MnO x ) are promising anode materials for lithium ion batteries, but they generally exhibit mediocre performances due to intrinsic low ionic conductivity, high polarization, and poor stability. Herein, yolk–shell nanorods comprising of nitrogen-doped carbon (N–C) coating on manganese monoxide (MnO) coupled with zinc manganate (ZnMn 2 O 4 ) nanoparticles are manufactured via one-step carbonization of α -MnO 2 /ZIF-8 precursors. When evaluated as anodes for lithium ion batteries, MnO@ZnMn 2 O 4 /N–C exhibits an reversible capacity of 803 mAh g −1 at 50 mA g −1 after 100 cycles, excellent cyclability with a capacity of 595 mAh g −1 at 1000 mAg −1 after 200 cycles, as well as better rate capability compared with those non-N–C shelled manganese oxides (MnO x ). The outstanding electrochemical performance is attributed to the unique yolk–shell nanorod structure, the coating effect of N–C and nanoscale size.