膨润土与水相互作用初步研究

为研究膨润土与水作用后对高放废物地质处置安全性产生的影响,将不同蒙脱石含量的临安钠基膨润土和兴和钙基膨润土置于水中长期浸泡3 000 h。结果表明:二种膨润土的膨胀指数皆随着蒙脱石含量的增加而增加,且最大膨胀指数与蒙脱石含量间的对数值呈线性关系;膨胀平衡后上清液中一价阳离子浓度大于二价阳离子的浓度,且随着蒙脱石含量的增加而增加,数据表明Na⁺浓度与膨润土中蒙脱石含量的对数值呈线性关系;上清液烘干后残留物质量随蒙脱石含量增加而增加,XRD图谱表明其中已存在蒙脱石。这些结果可作为进一步开展地质处置中缓冲材料与地下水相互作用的研究基础。

Preliminary study on interaction of bentonite and water

In order to study the interaction influence of bentonite and water on safety of geological disposal for high-level radioactive waste, two bentonites of different montmorillonite contents were immersed in water for 3 000 hours. Test results showed that their swell indexes increased with the increase of montmorillonite content, and a linear relationship was observed between the biggest swell index and logarithm of montmorillonite content. After swelling reached equilibrium, the concentration of univalent cation was larger than the concentration of divalent cation in supernatant and it increased with the increase of montmorillonite content; and there was also a linear relationship between sodium concentration and logarithm of montmorillonite content in two bentonites. The amount of dried residue of the supernatant also increased with the increase of montmorillonite content, and the XRD test results indicated that montmorillonite was present in dried residue of liquid supernatant. These experimental results can be a basis for further studies on interaction of buffer material and groundwater in geological disposal.