铁树叶水热炭及其去除溶液中铀U(Ⅵ)的研究

Adsorptive removal of U (Ⅵ) from aqueous solution by the biochar produced from hydrothermal carbonization

本文选用铁树叶为原料,采用温和的水热法制备出生物质炭。采用傅里叶变换红外光谱(FT-IR)探讨材料的成分,研究了溶液的初始pH值、初始铀浓度、温度和时间对吸附铀性能的影响,并从吸附热力学、动力学方面分析水热炭对U(VI)的吸附过程,探讨其吸附机理。结果表明溶液pH对吸附量的影响尤为显著,当pH为7时达到最大吸附量(54.66 mg g-1);在30 min时达到吸附平衡;吸附量随温度升高而不断增大。动力学研究结果表明铀在水热炭上的吸附符合准二级动力学模型和Langmuir吸附等温方程,Langmuir饱和吸附容量为56.5 mg g-1;热力学研究结果显示ΔH0=34.67 kJ mol-1,ΔG0<0,吸附过程在考察温度范围内为自发的吸热反应过程。

The biochar produced from hydrothermal cabonization （HTC） using iron leaves as raw material. The ability of HTC has been explored for the removal and recovery of uranium from aqueous solutions. The characteristics of HTC of ad- sorbing uranium（VI） from aqueous solutions were investigated at different conditions of pH, initial uranium concentration, contact,time and temperature. The results showed that maximum adsorbed amount of HTC were 54.66mg/g at initial pH of 7.0 and contact time of 30 rain. Adsorption kinetics was better described by the pseudo - second - order model and adsorption process could be well- described by the Langmuir isotherm. The thermodynamic parameters,G^0 （298 K）, H^0 and S^0 were determined to be - 17.28, 34.67 kJ mol^-1 and 174.23 J mol^-1 K^-1 ,demonstrate that adsorption process of HTC towards U（VI） was endothermic and spontaneous. The experimental results indicate that the HTC exhibit considerable potential for application in beth adsorption and removal of uranium from aqueous solutions.