临水河河流沉积物对铀的吸附行为研究

沉积物对铀的吸附行为是铀在河流中迁移转化的一个重要环节，揭示其吸附规律对河流水体污染防治有重要意义。为了研究临水河河流沉积物对铀的吸附机制，采用静态吸附试验，分析吸附时间、pH、铀初始浓度、离子种类、重金属对不同埋深（0~10、10~20、20~30、30~40 cm，分别以L1、L2、L3、L4表示)沉积物对铀的吸附影响，同时进行吸附动力学模型和等温吸附模型拟合。结果表明，不同埋深沉积物对铀吸附效果不同，吸附容量排列顺序为L1>L3>L2>L4，主要与沉积物中有机质含量和化学成分有关。动力学模型拟合表明，L1沉积物对铀的吸附为物理吸附和化学吸附，L2和L3主要为化学吸附，L4主要为物理吸附；L1与L3可以用Langmuir等温吸附模型描述其吸附过程，吸附为单分子吸附。L2与L4的吸附特性符合Freundlich等温吸附模型，为多分子层吸附，存在于非均质表面。在不同吸附介质中，Ca2+、Mg2+、CO32-对沉积物吸附铀都产生明显的抑制作用，且抑制效果Mg2+>CO32->Ca2+；Cd、Pb、Cu、Fe对吸附铀也有明显的抑制作用。

Study on Adsorption Behavior of Uranium in River Sediments of Linshui River

Adsorption behavior of uranium by sediment is an important link of uranium migration and transformation in rivers. It is great significance to reveal its adsorption rule for river water pollution prevention and control. In order to study adsorption mechanism of uranium by river sediments from Linshui river, static adsorption experiments were applied to analyze effects of adsorption time, pH value, initial concentration of uranium, ion types and heavy metals on uranium adsorption by sediments with different burial depths (0-10, 10-20, 20-30, and 30-40 cm, denoted by L1, L2, L3 and L4 respectively). The adsorption kinetics model and isothermal adsorption model were fitted at the same time. The results show that adsorption effect of uranium is different in sediments with different burial depths. The order of adsorption capacity is L1>L3>L2>L4, which mainly relates to organic matter content in sediment and chemical composition. According to kinetic model fitting, adsorption of uranium by L1 sediments is physical adsorption and chemical adsorption, L2 and L3 are mainly chemical adsorption, and L4 is mainly physical adsorption. The adsorption process of L1 and L3 can be described by Langmuir isothermal adsorption model, and the adsorption is monomolecular adsorption. The adsorption characteristics of L2 and L4 conform to Freundlich isothermal adsorption model, and adsorption is multi-molecular layer adsorption, which exists on heterogeneous surface. In different adsorption media, Ca2+, Mg2+ and CO32- have obvious inhibition effect on uranium adsorption from sediments, and the inhibition effect is Mg2+>CO32->Ca2+. Cd, Pb, Cu and Fe also have obvious inhibitory effects on uranium adsorption.