金属有机骨架和MXene复合材料用于高效快速海水提铀

A composite of metal-organic framework and MXene for efficient and rapid uranium extraction from seawater

MXene作为一种新型环境友好材料,因其化学性质不稳定,且不能有效地平衡层间的静电斥力,堆积和群聚阻碍了其有效表面和电子、离子的传输速度,限制了其实际应用.金属有机框架(MOFs)具有丰富的配位、可调节的孔隙率和超高的比表面积.本研究通过水热法将沸石咪唑框架(ZIFs)纳米颗粒与MXene纳米片结合起来,合成了ZIFs@MXene复合材料,并将其用于海水提铀.宏观实验发现,ZIF-8@MXene和ZIF-67@MXene均表现出优异的吸附效果,能够快速达到反应平衡(~30 min),吸附动力学数据符合准二级动力学模型.Freundlich模型很好地拟合了ZIF-8@MXene的热力学数据,其最大吸附能力为447.4 mg g^(-1),说明UO_(2)(CO_(3))_(2)^(2-)在复合材料表面进行多相吸附过程.Langmuir模型更好地拟合了ZIF-67@MXene的热力学数据,其最大吸附量为453.6 mg g^(-1),表明吸附过程是单层吸附并且活性位点均匀地分散在吸附剂上.根据反应前后X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)分析,发现羟基(–OH)、氮基(C=N–)和含氧官能团(Zn/Co–O和N–O)在吸附过程中共同作用,化学吸附和表面络合作用是ZIFs@MXene高吸附能力的作用机理.本研究为高性能吸附材料的构建以及海水中铀的提取提供了理论指导.

As a novel environmentally friendly material,MXene faces challenges due to its inherent chemical instability and ineffective compensation of interlayer electrostatic repulsion.The accumulation and clustering impede its effective surface and the rate of electron and ion transport,thus limiting its practical application.Metal-organic frameworks(MOFs)have rich coordination,tunable porosity and ultra-high specific surface.In this study,composite materials of ZIF-8@MXene and ZIF-67@MXene were synthesized via hydrothermal method.These composites combine zeolitic imidazole frameworks(ZIFs)nanoparticles with MXene nanosheets and were employed for the uranium extraction from seawater.Macroscopic experiments revealed that both ZIF-8@MXene and ZIF-67@MXene exhibited excellent adsorption effects and were able to reach reaction equilibrium quickly(~30 min).The adsorption kinetics data were found to be more consistent with a pseudo-second-order kinetic model.The Freundlich model fitted the thermodynamic dala of ZIF-8@MXene well wih a maximum adsoption capacity of 447.4 mg g^(-1)indiating that UO_(2)(CO_(3))_(2)^(2-).underwent a multiphase adsorption process on the composite surface.The Langmuir model better fitted the thermodynamic data of ZIF-67@Ti_(3)C_(2)T_(x)with a maximum adsorption capacity of 453.6 mg g^(-1),indicating that the adsorption process was monolayer adsorption and the active adsorption sites were uniformly dispersed on the adsorbent.According to the analysis of XPS and FTIR before and after reaction,it was found that hydroxyl groups(-OH),nitrogen groups(C=N-)and oxygen-containing functional groups(Zn/Co-O and N-O)acted together during the adsorption process,and chemisorption and surface complexation were the mechanisms for the high adsorption capacity of ZIFs@MXene.This study provided theoretical guidance for the design of high adsorption performance materials and the extraction of uranium from seawater.