U(Ⅵ)在石棉尾矿酸浸渣上的吸附

Sorption of U(Ⅵ) on acid leaching residue of asbestos tailings

为了研究U(Ⅵ)在石棉尾矿酸浸渣上的吸附行为,利用红外光谱仪、X射线衍射仪和扫描电镜等手段分别对石棉尾矿和石棉尾矿酸浸渣进行详尽表征。采用静态实验法考察吸附剂浓度、时间、pH、离子强度和温度等因素对吸附的影响,并进一步分析了吸附动力学和热力学。在研究范围内,U(Ⅵ)在石棉尾矿酸浸渣上的吸附受pH值、离子强度和温度的影响明显。当pH<6时,吸附率随pH的增大而增大,此时吸附作用主要是离子交换作用或表面络合;当pH>6,随pH的增大吸附率会降低,且离子强度越大,吸附率越低,则表明静电吸附或表面络合是其主要的吸附机制。动力学符合准二级动力学方程,热力学符合Langmuir吸附等温线方程。

The asbestos tailing and acid leaching residue were characterized thoroughly by X-ray diffraction（ XRD）,Fourier transfer infrared spectroscopy（ FT-IR）,and scanning electron microscopy（ SEM）. Sorption experiments were conducted as a function of adsorbent concentration,time,pH,ionic strength,and temperature by using the static experimental method. In addition,the kinetic and thermodynamic models were also studied,and the results indicate that sorption of U（ Ⅵ） onto acid leaching residue is influenced by pH,ionic strength,and temprature. The main sorption mechanism below pH 6 is an ion exchange or outer complexation. However,the sorption of U（ Ⅵ） decreases with increasing pH when the pH is above 6,indicating that the main sorption mechanism in this regime is an electrostatic interaction or outer complexation. The pseudo-second-order rate equation fits the kinetic model well,and the sorption isotherms conform to a Langmuir model.