沉积物中^(129)I不同形态的逐级浸取分离

Sequentially Leaching ^(129)I in Sediment with Different Morphologies

随着核技术的不断发展,核试验、乏燃料后处理及核电站事故等人类核活动向自然界释放了大量的^(129)I。^(129)I在沉积物中的含量与化学形态分布对揭示其迁移规律和沉降信息有着重要的意义。因此,对于研究沉积物中^(129)I不同形态所需要的合理分离及制备流程就尤为重要。结合太湖湖泊沉积物的特点并通过比较众多沉积物中^(129)I形态的分离流程,提出了改进的逐级浸取流程。在温度、时间不同的实验条件下,对沉积物样品分离出沉积物中^(129)I可交换态、有机结合态、金属氧化物态、残余矿物态四种不同形态,并通过高温热解法及125I示踪计算回收率及损失率。改进后的逐级浸取法能达到90%的提取效率,离子可交换态、有机结合态、金属氧化物结合态的适宜浸取时间和温度分别为4.5h、30℃,4.5h、75℃,5.5h、75℃。流程适用于同类湖底沉积物样品分析。

Along with the development of nuclear technology, human nuclear activities including nuclear experiment, nuclear fuel reprocessing and accident of nuclear power plants, etc. , lead to plenty of leakage of 129I into nature. The content of 129I in the sediment and its chemical form distribution is of great importance to reveal its migration patterns and settlement information. Therefore, it is very important to study the proper separation and preparation process for the 129I in sediment with different morphologies. According to the characteristics of the sediment in Taihu Lake and through comparing many separation processes for separating different 129I form in sediment, this paper proposed an improved sequential leaching process. By this process, under different temperature and with different times, four different forms of 129 I, including leachable state, organic material, oxides reducible and residue mineral bound states, were separated. Recovery rates and loss rates were calculated through high temperature pyrolysis experiment and 125I tracer. The extraction efficiency of the improved sequential leaching process can reach 90%. The suitable time and temperature for separating leachable state, organic material and oxides reducible were 4.5 h, 30℃; 4.5 h, 75℃;5.5 h, 75℃, respectively. The results indicates that the process can also be applied to the same kind of lake sediment sample analysis.