Coagulation behavior of humic acid in aqueous solutions containing Cs+, Sr2+ and Eu3+: DLS, EEM and MD simulations
Coagulation behavior of humic acid in aqueous solutions containing Cs+, Sr2+ and Eu3+: DLS, EEM and MD simulations
复制标题
腐植酸在含有 Cs、Sr2 和 Eu3 的水溶液中的混凝行为：DLS、EEM 和 MD 模拟
DOI：
10.1016/j.envpol.2018.02.019
复制
发表时间：
2018
影响因子：
8.9
通讯作者：
Wang Xiangke
中科院分区：
文献类型：
--
作者：
Tan Liqiang;Tan Xiaoli;Mei Huiyang;Ai Yuejie;Sun Lu;Zhao Guixia;Hayat Tasawar;Alsaedi Ahmed;Chen Changlun;Wang Xiangke
采用动态光散射（DLS）技术，结合光谱分析和分子动力学（MD）模拟，研究了不同pH值（2.8，7.1和10.0）下腐殖酸（HA）与Cs+（10-500 mM）、Sr 2+（0.8-10.0 mM）和Eu 3+（0.01-1.0 mM）的混凝行为。随着核素浓度的增加，混凝速率和平均流体动力学直径（<Dh>）显著增加。<Dh>在<Dh>较高的Sr 2+浓度下，可以缩放到100 μ m，这表明HA凝固与扩散限制胶体聚集（DLCA）模型一致。三价Eu 3+在比二价Sr 2+和单价Cs+低得多的浓度下诱导HA凝固。Sr 2+和Eu 3+与Cs+的凝聚值比值几乎与Z−6成正比，表明HA凝聚过程基本符合Schulze-Hardy规则。光谱分析表明，核素与HA分子的羧基/酚基之间的络合作用在HA的凝聚过程中起着重要作用。MD模型表明，Sr 2+和Eu 3+离子通过形成带负电荷的HA分子之间的分子内或分子间桥来增加凝血过程，而对于Cs+，没有形成分子间桥。这项工作提供了新的见解HA和放射性核素之间的相互作用，并提供了一个预测HA在运输和消除放射性核素在严重污染的环境中的作用。
The coagulation behaviors of humic acid (HA) with Cs+(10–500 mM), Sr2+(0.8–10.0 mM) and Eu3+(0.01–1.0 mM) at different pH values (2.8, 7.1 and 10.0) were acquired through a dynamic light scattering (DLS) technique combined with spectroscopic analysis and molecular dynamic (MD) simulations. The coagulation rate and the average hydrodynamic diameter (<Dh>) increased significantly as the concentration of nuclides increased. <Dh> could be scaled to timetas <Dh>∝ taat higher Sr2+concentrations, which shows that HA coagulation is consistent with the diffusion-limited colloid aggregation (DLCA) model. Trivalent Eu3+induced HA coagulation at a much lower concentration than bivalent Sr2+and monovalent Cs+. The coagulation value ratio of Sr2+and Eu3+to Cs+is almost proportional to Z−6, indicating that the HA coagulation process is generally consistent with the Schulze-Hardy rule. Spectroscopic analysis indicated that the complexation between nuclides and carboxylic/phenolic groups of HA molecules played important roles in the coagulation of HA. MD modelling suggested that Sr2+and Eu3+ions increased the coagulation process through the formation of intra- or inter-molecular bridges between negatively charged HA molecules, whereas for Cs+, no inter-molecular bridges were formed. This work offers new insight into the interactions between HA and radionuclides and provides a prediction for the roles of HA in the transportation and elimination of radionuclides in severely polluted environments.