摘要
为了准确模拟钚在地下水中的大尺度迁移行为,需要掌握地下水三相体系中钚(Ⅳ)-天然胶体-不动介质(花岗岩)间的作用机制。实验结果表明,钚(Ⅳ)吸附在土壤胶体表面生成的钚(假)胶体有很强的运动能力(钚(假)胶体在装有孔隙介质的柱体中传输后钚的回收率R反映其运动能力),其运动能力R随土壤胶体质量浓度ρ的增大而增大(0≤ρ≤375.4 mg/L,1.3%≤R≤52.5%)。钚(Ⅳ)在土壤胶体表面生成的主要配位种态是≡SOPu(OH)_(3),种态百分数>95%,且种态百分数与胶体浓度正相关。实验和表面配位计算证实,钚(假)胶体增强了钚的运动能力,比水溶态钚污染远场水域的风险更大。DLVO作用势计算结果指出,随着胶体浓度的继续增大,胶体-介质间第二能量最小值(Ф_(min2))的波谷深度加深。该引力相互作用势导致钚(假)胶体在介质表面的吸着沉积效率增大,且与实验观察到的逐渐变弱的钚(假)胶体的运动能力一致(375.4 mg/L≤ρ≤2017.8 mg/L,52.5%≤R≤12.7%)。
In order to accurately simulate the large-scale migration of plutonium in groundwater(a threephase system),it is necessary to understand the interaction mechanisms between plutonium(Ⅳ),natura colloid,and granite(immobile media).The experimental results show that plutonium pseudo-colloids(i.e.Pu(Ⅳ)sorbed on the surfaces of soil colloids)have the strong mobility(i.e.,the recovery percentage of plutonium after plutonium pseudo-colloids transported through columns filled with pore media,R).The mobility R increases with soil colloid concentrationρ(0≤ρ≤375.4 mg/L,1.3%≤R≤52.5%).The master complexation speciation of Pu(Ⅳ)on the surfaces of soil colloids is≡SOPu(OH)_(3).The speciation percentage(>95%)is positively correlated with the colloid concentration.The results of experiments and surface complexation calculations confirm that plutonium pseudo-colloids enhance the mobility of Pu(Ⅳ)and thus pose a greater risk of contaminating far-field waters than the dissolved Pu(Ⅳ).The calculations of DLVO interaction potential indicate that the trough depth of the second energy minima(Ф_(min2))between colloids and media deepens with increasing colloid concentrations.This attractive interaction potentia results in an increase in the adsorptive deposition efficiency of plutonium pseudo-colloids on the media surfaces.The DLVO calculations are consistent with the observation:the mobility of plutonium pseudocolloids become weak(375.4 mg/L<ρ≤2017.8 mg/L,52.5%<R≤12.7%).
作者
谢金川
李红霞
王煜
XIE Jin-chuan;LI Hong-xia;WANG Yu(Institute of Military-Civilian Integration Technology,Northwest University of Political Science and Law,Xi’an 710122,China;Northwest Institute of Nuclear Technology,Xi’an 710024,China)
出处
《核化学与放射化学》
CAS
CSCD
北大核心
2024年第5期490-498,I0003,共10页
Journal of Nuclear and Radiochemistry
基金
陕西省自然科学基础研究计划(2023-JC-YB-278)
国家自然科学基金(21477097)。
关键词
土壤胶体
钚(假)胶体
运动能力
表面配位
DLVO作用势
soil colloid
plutonium pseudo-colloid
mobility
surface complexation
DLVO interaction potential
