放射性核素在海洋环境吸附体系中的固体浓度效应

Particle concentration effect of radionuclides in marine environment adsorption system

通过Ag-110m在海洋沉积物中的静态吸附-解吸实验,系统地研究了放射性核素在海洋环境吸附体系中的固体浓度效应。实验结果表明:Ag-110m在海洋沉积物中的吸附-解吸等温线趋近于线性,且随着固体浓度的升高,等温线呈下降趋势,存在固体浓度效应。解吸等温线比吸附等温线滞后,固体浓度0.1~1.0g·L^(-1)范围内,吸附滞后角(θ)随着固体浓度的增加逐渐增大,不可逆性明显增强,固体浓度改变了吸附体系的不可逆性,符合"亚稳平衡吸附理论"对固体浓度效应产生机制的预测,而固体浓度达到3.0g·L^(-1)后,吸附-解吸等温线几乎重合,体系接近可逆反应。因此对于放射性核素,存在一个区间范围使得吸附体系的不可逆程度随固体浓度的增加而增大,但是超过区间的上、下限值后,体系趋近于可逆反应。应用Freundlich-SCA表面组分活度模型,用活度代替浓度,校正实际与理想吸附体系间的偏离,将不同固体浓度下的吸附-解吸实验数据分别归入同一条吸附等温线和解吸等温线,可以用来预测其他固体浓度下的吸附-解吸平衡状态。

The particle concentration effect of radionuclides in marine environment adsorption system was systematically studied through static adsorption-desorption experiments of Ag-110m in marine sediments.The experimental results showed that adsorption-desorption isotherms of Ag-110m in marine sediments tended to be linear and existed particle concentration effect phenomenon be-cause of the isotherms decreased with the increasing of particle concentration.The desorption isotherm lagged behind the adsorption isotherm and angle between them was calledaadsorption hysteresis angle(0)”.When the particle concentration ranged from0.1g?L1to1.0g?L1,was gradually increased as the concentration of particle increases.That means the particle concentration changed the irreversibility of the adsorption system and irreversibility increased markedly.The results was fully justified the prediction to the mechanism of particle concentration effects using“metastable equilibrium adsorption theory”.When the particle concentration reached3.0g?L1,the adsorption-desorption isotherms almost coincided and the system become reversible.For the radionuclides adsorption system,there is an interval so that the degree of irreversibility increase with the increasing of solid concentration,but after exceeding the upper and lower values of that interval the system tend to be reversible.Using activity instead of concentration,the de-viates between actual and ideal adsorption system could be corrected,and using Freundlich-SCA surface activity of component model adsorption and desorption experiments data under different solid concentration can be classified as the same adsorption isotherm or desorption isotherms Which can be used to predict the adsorption desorption of other solid concentration under the equilibrium state.