木质素表面功能化MXene纳米片的制备及其对U(Ⅵ)的吸附性能

Preparation of lignin surface-functionalized MXene nanosheets and its U(Ⅵ)adsorption properties

为了进一步改善MXene纳米材料对模拟放射性废水中U(Ⅵ)的吸附性能,利用天然资源酶水解木质素(EHL)作为生物表面活性剂对MXene进行表面功能化处理,采用SEM-EDS、XRD及FTIR对改性前后的材料进行了表征分析,并在吸附实验中探究了pH、温度、反应时间、干扰离子及不同初始U(Ⅵ)浓度等因素对除U(Ⅵ)效果的影响。结果表明,EHL阻止了MXene纳米片的聚集堆叠,并且引入了大量活性官能团,提高了EHL功能化MXene纳米片的吸附性能。在MXene与EHL的质量比为1∶5、投加量为0.1 g·L^(−1)、pH为5、温度为303 K时,对U(Ⅵ)的最大吸附容量为231.95 mg·g^(−1)。此外,吸附动力学和等温线分析表明,拟二级动力学模型和Freundlich等温线模型能很好地拟合此吸附过程,热力学分析表明其吸附过程是自发吸热的。经历5次循环再生后,对U(Ⅵ)的去除率仍在80%以上。表征分析结果表明,MX/EHL与U(Ⅵ)之间相互作用机制包括离子交换、静电吸引以及与含氧官能团之间的络合作用。基于此研究,MX/EHL作为一种环境友好型吸附材料,对去除废水中的U(Ⅵ)具有巨大潜力。

In order to further improve the adsorption performance of MXene nanomaterials on U(Ⅵ)in simulated radioactive wastewater,the surface functionalization of MXene was carried out by using natural resources of enzymatically hydrolyzed lignin(EHL)as a biosurfactant,and the materials before and after the modification were characterized and analyzed by using SEM-EDS,XRD,and FTIR,and the effects of pH,temperature,and the adsorption experiments were explored,reaction time,interfering ions and different initial U(Ⅵ)concentrations on the effect of U(Ⅵ)removal.The results show that EHL prevents the re-stacking of MXene nanosheets and introduces a large number of active functional groups,which improves the adsorption performance of EHL-functionalized MXene nanosheets.The maximum adsorption capacity for U(Ⅵ)is 231.95 mg·g^(−1)at the mass ratio of MXene to EHL of 1∶5,the dosage of 0.1 g·L^(−1),pH=5,and the temperature of 303 K.In addition,the adsorption kinetic and isotherm analyses show that the proposed second-order kinetic model and the Freundlich isotherm model fit this adsorption process well,and the thermodynamic analyses indicate that its adsorption process is spontaneous heat absorption.After five cycles of regeneration,the removal rate of U(Ⅵ)is still above 80%.Characterization results reveals that the interaction mechanisms between MX/EHL and U(Ⅵ)involve ion exchange,electrostatic attraction,and complexation with oxygen-containing functional groups.Based on this study,MX/EHL has great potential as an environmentally friendly adsorbent material for the removal of U(Ⅵ)from wastewater.