Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China.
J Hazard Mater. 2022 Feb 15;424(Pt A):127371. doi: 10.1016/j.jhazmat.2021.127371. Epub 2021 Sep 28.
Heterogeneity in sediment and aquifer is universal, resulting in preferential flows of injected materials in the high permeability regions and forming flow by-passed zones in the low permeability regions during in-situ subsurface remediation. This adverse effect can considerably delay the completion of remedial operations and significantly increase the cost. Column experiments were designed and conducted to study the transport of starch- and starch-xanthan gum modified Fe-Mn binary oxide particles (SFM and SXFM) in saturated heterogeneous porous media and to reveal the particles' arsenic (As) stabilization performance. Fine-in-Coarse (FIC) and Coarse-in-Fine (CIF) patterns of heterogeneous packings were set up in the columns. Testing results demonstrated that starch-xanthan gum dual treatment on Fe-Mn binary oxides successfully improved the particles' migration capability in heterogeneous porous media and their distribution uniformity attributed to the profound shear thinning behavior of xanthan gum solution. The addition of xanthan gum to the system increased the viscosity and shear thinning property of the SXFM suspension, making it a better candidate for delivery. Both SFM and SXFM stabilized As in heterogeneously packed sediment collected from a contaminated site, with SXFM showing better stabilization performance than SFM. The stabilization effects of SXFM were 90.7-97.0%, compared to 82.0-95.2% of SFM.
在原位地下修复过程中，由于沉积物和含水层的非均质性是普遍存在的，注入的物质会优先在高渗透性区域流动，并在低渗透性区域形成绕过流动的区域。这种不利影响会极大地延迟修复作业的完成，并显著增加成本。设计并进行了柱实验，以研究淀粉和淀粉-黄原胶改性的 Fe-Mn 二元氧化物颗粒（SFM 和 SXFM）在饱和非均质多孔介质中的传输，并揭示颗粒的砷（As）稳定性能。在柱中设置了细-粗（FIC）和粗-细（CIF）非均质包装模式。测试结果表明，淀粉-黄原胶对 Fe-Mn 二元氧化物的双重处理成功地提高了颗粒在非均质多孔介质中的迁移能力及其分布均匀性，这归因于黄原胶溶液的强烈剪切变稀行为。黄原胶的加入增加了 SXFM 悬浮液的粘度和剪切变稀特性，使其成为更适合输送的物质。SFM 和 SXFM 都能稳定从污染场地采集的非均质包装沉积物中的 As，而 SXFM 的稳定性能优于 SFM。SXFM 的稳定效果为 90.7-97.0%，而 SFM 的稳定效果为 82.0-95.2%。
