地质水泥对U(Ⅵ)的吸附行为及其机理研究

针对具有放射性的含铀废液，本实验采用间歇法，选用养护28 d、粒径为200~220 μm的地质水泥颗粒作为吸附剂，通过改变水泥投加量、吸附时间、pH值、U(Ⅵ)浓度、溶液温度等环境因素，研究地质水泥对U(Ⅵ)的静态吸附规律，为评估含U(Ⅵ)地质水泥固化体的固有稳定性提供依据。结果表明，在较低固液比（0.5 g/L）和较短时间（1.5 d）内，地质水泥对不同浓度U(Ⅵ)的吸附率达99.9%以上，且吸附量受U(Ⅵ)浓度和环境因素（pH值、溶液温度）的影响较小，吸附条件温和。热力学行为更符合Langmuir等温吸附模型，意味着该过程是一个吸热、以单层吸附为主的吸附过程。吸附材料结构表征结果证实，该吸附过程同时存在物理（静电吸引）与化学（离子交换）两种吸附机制。

Study on Adsorption Behavior and Mechanism of U(Ⅵ) by Geological Cement

For the radioactive uranium-containing waste liquid, the static adsorption behavior of U(Ⅵ) by geological cement was studied by changing cement dosage, contact time, pH, U(Ⅵ) concentration, and solution temperature using the batch adsorption method in the experiment. The experimental results show that the adsorption rate of U(Ⅵ) is over 99.9% under the condition of low solid-liquid ratio (0.5 g/L) and a short period of time (1.5 d), and the U(Ⅵ) concentration and environmental factors such as pH and temperature have little effect on the adsorption capacity, so the adsorption conditions are very mild. The thermodynamic behavior is more consistent with the Langmuir model, meaning that the U(Ⅵ) adsorption by geological cement is a monolayer adsorption based process. The analysis results of material characteristics show that there are physical and chemical coexistence adsorption mechanisms for the U(Ⅵ) adsorption by geological cement.