MnO2/Ti3C2TX复合剂对水中U(VI)的吸附性能与机制

Adsorption performance and mechanism of MnO2/Ti3C2TX composite towards U(VI) in water

  • 摘要: 针对Ti3C2TX纳米片层易堆叠和吸附位点少的不足,采用水热法制备了MnO2/Ti3C2TX复合剂。通过单因素试验探讨铀的初始浓度、投加量、pH值、时间和共存离子对其吸附U(VI)的影响,采用现代表征手段分析MnO2/Ti3C2TX的表面性质及吸附U(VI)的作用机制。试验结果表明:在U(VI)初始浓度5 mg·L−1、MnO2/Ti3C2TX投加量为0.1 g·L−1、温度303 K、pH值为6时,30 s内U(VI)浓度降至0.41 mg·L−1,30 min后吸附达到平衡,其对U(VI)的吸附率达99.15%,吸附容量为49.58 mg·g−1。经过5次循环后,MnO2/Ti3C2TX对U(VI)的吸附效率仍保持在96.3%,具有良好的可再生利用性。整个吸附过程为自发吸热过程,符合拟二级动力学模型和Freundlich等温线模型。BET分析表明MnO2/Ti3C2TX的比表面积达318.3 m2·g−1,较Ti3C2TX高55.9倍。FTIR和XPS分析表明MnO2/Ti3C2TX对U(VI)吸附主要是表面含氧基团与铀的配位络合。

     

    Abstract: To address the shortcomings of Ti3C2TX nanosheets, which tend to stack and have limited adsorption sites, a MnO2/Ti3C2TX composite was prepared using the hydrothermal method. The influence of uranium initial concentration, dosage, pH, time, and interfering ions on U(VI) adsorption was investigated through single-factor adsorption experiments. Modern characterization techniques were employed to analyze the surface properties of MnO2/Ti3C2TX and the mechanism of U(VI) adsorption. Experimental results revealed that with an initial U(VI) concentration of 5 mg·L−1, MnO2/Ti3C2TX dosage of 0.1 g·L−1, and a temperature of 303 K, pH of 6, the U(VI) concentration dropped to 0.41 mg·L−1 within 30 s. Adsorption equilibrium was reached after 30 min, with an adsorption rate of 99.15% and an adsorption capacity of 49.58 mg·g−1. After five cycles, the adsorption efficiency of MnO2/Ti3C2TX remained at 96.3%, demonstrating its potential for regeneration and reuse. The entire adsorption process was endothermic and spontaneous, fitting the pseudo-second-order kinetic model and the Freundlich isotherm model. BET analysis showed that the specific surface area of MnO2/Ti3C2TX reached 318.3 m2·g−1, which is 55.9 times higher than that of Ti3C2TX. FTIR and XPS analyses indicated that the primary mechanism of U(VI) adsorption on MnO2/Ti3C2TX is the coordination complexation between surface oxygen-containing groups and uranium.

     

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