| 饱和多孔介质中水流停滞对胶体吸附与解吸的影响 |
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| 引用本文： | 袁瑞强,张文新,王仕琴.饱和多孔介质中水流停滞对胶体吸附与解吸的影响[J].环境科学研究,2020,33(2):431-437. |
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| 作者姓名： | 袁瑞强 张文新 王仕琴 |
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| 作者单位： | 1.山西大学环境与资源学院, 山西 太原 030006 |
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| 基金项目： | 国家自然科学基金项目（No.41301033） |
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| 摘 要： | 地下水水流停滞区域是胶体污染物吸附的重要场所.为研究水流停滞时间对胶体在饱和多孔介质中再迁移的影响，在石英砂柱与胶体达到稳定吸附后中断水流，分别设置水流停滞时间0、15、32、64、87、120 h，比较胶体的再迁移能力.结果表明:①水流停滞时间在32 h以内时，通入去离子水可使5.2%~5.3%的胶体被解吸出来再次随水流迁移，解吸量介于0.54~0.56 mg之间，对胶体再迁移能力的影响不明显；水流停滞时间为32~120 h时，水流停滞时间增加会导致胶体再迁移能力降低；水流停滞时间达到120 h，胶体主要楔在石英砂颗粒间，难以被解吸出来，此时仅有1.8%的胶体再次随水流迁移.②水流停滞时，以自上而下的流通方式吸附在土柱中的胶体受重力作用可能跨过能垒吸附在初级势阱中，使再迁移能力降低；然而在自下而上的流通方式下吸附在土柱中的胶体受重力影响难以跨过能垒吸附在初级势阱中，胶体再迁移能力较强.③当以≤ 30.2 m/d的流速通入背景液时，流速对胶体解吸的影响不如通入去离子水时显著.研究显示，水流停滞时间对吸附在饱和含水介质上胶体的再迁移能力有明显影响，重力作用在不同的流通方式下不同.
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| 关 键 词： | 水流停滞 迁移 吸附-解吸 胶体 |
| 收稿时间： | 2019/1/10 0:00:00 |
| 修稿时间： | 2019/5/7 0:00:00 |
Effects of Flow Stagnation on Colloidal Retention-Release in Saturated Porous Media |
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| YUAN Ruiqiang,ZHANG Wenxin,WANG Shiqin.Effects of Flow Stagnation on Colloidal Retention-Release in Saturated Porous Media[J].Research of Environmental Sciences,2020,33(2):431-437. |
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| Authors: | YUAN Ruiqiang ZHANG Wenxin WANG Shiqin |
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| Affiliation: | 1.School of Environment and Resource, Shanxi University, Taiyuan 030006, China2.Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China |
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| Abstract: | Regions with groundwater flow stagnation are important areas where pollutants tend to be adsorbed onto porous media. In order to determine the effects of the duration of groundwater flow stagnation on colloidal retention and release, after adsorption of colloids in quartz sand columns,experiments with flow stagnation of 0, 15, 32, 64, 87 and 120 h were conducted to evaluate the remigration capacity of colloids. The results show that:(1) 0.54-0.56 mg of colloids was released, accounting for 5.2%-5.3% of the retained colloids by flushing with deionized water when flow stagnation duration was less than 32 h, which suggests a weak effect of flow stagnation duration on the remigration of colloids. When the water flow stagnation duration lasted from 32 h to 120 h, colloidal remigration ability reduced gradually. All the adsorbed colloids were mainly wedged between the quartz particles with only 18% colloids were released when the period of flow stagnation reaching 120 h. (2) During flow stagnation, gravity can make the originally adsorbed colloidsin the secondary minimums slip across the energy barrier and adsorb in the primary minimums. As a result, the colloids that were adsorbed by top-down flow pattern showed enhanced retention capacity. The bottom-up flow pattern caused most of colloids to remain in the secondary minimum under the influence of gravity. Colloids had strong remigration capacity during the process of flow stagnation. (3) The effects of flow rate of solution in quartz sand on colloidal release were insignificant when the flow rate was less than or equal to 30.2 m/d, although the effect was significant when the porous media was flushed with deionized water. Hydrodynamic shear stress could be enhanced with an increased flow rate, pushing some of the originally adsorbed colloids in primary minimums across the energy barriers to the secondary minimums, which induces a small amount of colloid release. Flushing with deionized water decreased or even eliminated the secondary minimums of the porous media particles, and caused the release of large amounts of colloids. |
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| Keywords: | flow stagnation transport retention-release colloids |
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