生物炭对模拟废水中U(Ⅵ)的吸附动力学与热力学研究

Adsorption Kinetics and Thermodynamics Analysis of U(VI)in Simulated Wastewater

结合静态吸附法和红外光谱、拉曼光谱表征分析考察了生物炭对模拟废水中U(Ⅵ)的吸附,结果表明生物炭可以有效的去除废水中的U(Ⅵ),在1 h可以快速达到吸附平衡。此外U(Ⅵ)吸附的最佳pH在6.0~6.5。动力学分析表明准二级动力学模型可以更好的拟合生物炭吸附U(Ⅵ)的动力学过程,由此可得U(Ⅵ)吸附的主要机理是U(Ⅵ)与生物炭表面的功能基团发生了化学键合作用。不同温度下的等温线拟合分析表明温度升高促进U(Ⅵ)在生物炭上的吸附,热力学分析揭示了U(Ⅵ)在生物炭上的吸附是一个自发吸热过程。Freundlich模型有效拟合了U(Ⅵ)吸附等温线,意味着生物炭表面不均匀,从而使U(Ⅵ)发生了多层吸附。红外和拉曼光谱分析进一步揭示了U(Ⅵ)与生物炭的表面官能团之间的键合作用。研究结果证实生物炭在含铀废水处理中具有潜在的应用价值。

Combined with static adsorption method,infrared spectrum and Raman spectral characterization analysis,the adsorption of U(Ⅵ)in the simulated wastewater was investigated.The results showed that biochar could effectively remove U(Ⅵ)in the wastewater,quickly reaching the adsorption equilibrium within an hour.In addition,the adsorption effect achieved best when pH was at 6.0~6.5.The kinetic analysis showed that the pseudo-second-order kinetic model could better fit the process of biochar adsorption of U(Ⅵ),which meant that the main mechanism of adsorption was that U(Ⅵ)and the functional group of the biochar surface had a chemical bond cooperation.Isotherm fitting analysis at different temperatures showed that the temperature increase promoted the adsorption of U(Ⅵ)on the biochar.Thermodynamic analysis revealed that the adsorption of U(Ⅵ)on the biochar was a spontaneous endothermic process.The Freundlich model well fited the U(Ⅵ)adsorption isotherm,which meant that the surface of the biochar was uneven,thus making the U(Ⅵ)undergo multi-layer adsorption.Infrared and Raman spectroscopy further revealed the bonding effect between U(Ⅵ)and the surface functional groups of the biochar.The results confirmed that biochar had potential applications in the treatment of uranium-containing wastewater.