还原条件下膨润土胶体稳定性研究

Study on the Stability of Bentonite Colloids Under Reducing Conditions

还原条件下,膨润土胶体的稳定性与环境中放射性核素在花岗岩裂隙中的吸附迁移息息相关。本文主要模拟在还原条件下,探究离子强度(Na+、Ca 2+)和pH值对膨润土胶体稳定性的影响,进行了SeO_(3)^(2-)浓度的影响试验。结果表明,碱性条件下,膨润土胶体的稳定性较好;当SeO_(3)^(2-)的浓度高于8×10^(-3) mol/L时,膨润土胶体的粒径变化显著;相对于阳离子(Na^(+)、Ca^(2+))的CCC(临界聚焦浓度)值(1×10^(-2) mol/L、4×10^(-3) mol/L),SeO_(3)^(2-)的CCC值较小,对胶体粒径的影响也较小;当SeO_(3)^(2-)的浓度降至2×10^(-3) mol/L时,膨润土胶体的粒径可以恢复到试验初始状态时胶体的粒径。

The stability of bentonite colloids under reducing conditions is closely related to the adsorption and migration of radionuclides from the environment in the granite fissures.This paper mainly simulates the effect of ionic strength(Na+,Ca 2+)and pH on the stability of bentonite colloids under reducing conditions,focusing on the effect of SeO_(3)^(2-) concentration.The results show that the stability of bentonite colloids is better under alkaline conditions;when the concentration of SeO_(3)^(2-) is higher than 8×10^(-3) mol/L,the particle size of bentonite colloids changes significantly;compared with the CCC values of cations(Na^(+)、Ca^(2+))(1×10^(-2) mol/L,4×10^(-3) mol/L),the CCC value of SeO_(3)^(2-) is small,and the influence on the particle size of the colloids is small;when the concentration of SeO_(3)^(2-) is reduced to 2×10^(-3) mol/L,the particle size of the bentonite colloid can be restored to that of the colloid at the initial state of the test.