MXene/SA凝胶微球的制备及对U(VI)的吸附性能

Preparation of MXene/SA gel microspheres and its adsorption performance for U(VI)

  • 摘要: 为了提高纳米材料MXene的吸附能力和可回收性,采用离子交联法将海藻酸钠(SA)和MXene混合,使Ti3C2Tx MXene纳米材料固定在SA凝胶基质上,经冷冻干燥后制备了MXene/SA凝胶微球。通过SEM-EDS、FTIR和XPS对凝胶微球结构进行了表征,并考察了不同因素影响下MXene/SA凝胶微球对水溶液中铀(VI)的吸附特性,并探究了其循环再生能力。结果表明,MXene/SA凝胶微球对铀吸附过程遵循拟二级动力学和Langmuir等温吸附模型,说明该吸附主要为单分子层化学吸附,且热力学参数表明其吸附过程是一个自发吸热的过程。在pH为4,温度为298 K时,MXene/SA凝胶微球对铀的最大吸附量为126.82 mg·g−1,其主要吸附机制是离子交换与络合作用。更重要的是该凝胶微球经5次循环后,去除率仍然保持在90%以上,说明吸附剂具有回收再生利用性能,且不会造成水环境的二次污染。因此,MXene/SA凝胶微球吸附剂在修复放射性核素铀废水污染方面表现出巨大潜力。

     

    Abstract: In order to improve the adsorption capacity and recyclability of the nanomaterial MXene, sodium alginate (SA) and MXene were mixed by ion cross-linking method to fix the Ti3C2Tx MXene nanomaterial on the SA aerogel matrix. After freeze-drying, MXene/SA gel microspheres was prepared. The structure of the gel microspheres was characterized by SEM-EDS, FTIR and XPS, and the adsorption characteristics of MXene/SA gel microspheres to uranium (VI) in aqueous solution were investigated under the influence of different factors, and its recycling ability was explored. The results show that the adsorption of uranium by MXene/SA gel microspheres follows the pseudo-second-order kinetics and Langmuir isotherm adsorption model, indicating that the adsorption is mainly monolayer chemical adsorption, and the thermodynamic parameters indicate that the adsorption process is a spontaneous endothermic. When the pH is 4 and the temperature is 298 K, the maximum adsorption capacity of MXene/SA gel microspheres for uranium is 126.82 mg·g−1. The main adsorption mechanism is ion exchange and complexation. More importantly, after 5 cycles of the gel microspheres, the removal rate remains above 90%, indicating that the adsorbent has the performance of recycling and reuse and will not cause secondary pollution to the water environment. Therefore, MXene/SA gel microsphere adsorbent has shown great potential in repairing the pollution of radionuclide uranium wastewater.

     

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