新型低碳凝胶材料固化锌污染土的试验研究以及分子动力学模拟解析

Experimental study and analysis of molecular dynamics simulation of new low carbon gel material for Solidification/Stabilization of Zn^(2+) contaminated soil

利用石灰石煅烧粘土水泥(LC3)混合制成的新型低碳凝胶材料和普通硅酸盐水泥(OPC)固化/稳定化锌污染土进行研究.通过毒性浸出试验和分子动力学模拟,探究固化污染土的环境安全特性及动力学特性.研究结果表明:常规养护条件下,LC3和OPC固化污染土无侧限抗压强度随龄期和掺量增长而提高;相同条件下,LC3固化锌污染土的强度高于OPC固化土.相较于未处理污染土,LC3固化土的锌离子浸出浓度降低了20.1~94.1倍,OPC固化土的锌离子浸出浓度降低了1.2~319.3倍.在浓度为Zn0.5时,OPC固化效率要优于LC3固化土,而浓度为Zn1.5时,LC3固化试样中锌离子迁移率则更低.通过分子动力学模型研究Zn2+的强度分布、迁移路径和扩散系数.结果表明,LC3主要是通过分子间作用、阳离子交换、吸附以及络合等形式限制锌离子的迁移,在整个纳米孔道内,锌离子的平均扩散系数为0.06×10-8m2/s.

The limestone calcined clay cement(LC3)as a low-carbongel material andordinary portland cement(OPC)isused to Solidification/Stabilization(S/S)soil contaminated with excessive Zn^(2+).Toxicity leaching test and molecular dynamics simulation are conducted to evaluate environmental safety and dynamics properties of solidified contaminated soils.The results of the study show that compared with untreated contaminated soils,under regular maintenance conditions,the leached Zn concentrations in the LC3 stabilized samples reduce 20.1~94.1 times and the leached Zn concentrations in the OPC stabilized samples reduce 1.2~319.3 times.When Znconcentrations is Zn0.5,the OPC stabilized samples provide superior Zn immobilization compared to LC3 stabilized soils.Whereas Znconcentrations is Zn1.5,mobility of Zn^(2+) in LC3 stabilized samples is lower than OPC stabilized samples.Strength distribution,migration paths and diffusion coefficients of Zn^(2+) are studied by molecular dynamics modeling.The results show that LC3 restricts the migration of zinc ions mainly by intermolecular interaction,cation exchange,adsorption and complexation.In the nanopore,mean diffusion coefficients of Zn2+is 0.0610-8 m2/s.