蒙脱石胶体及其携带叶枯唑在多孔介质中的运移规律研究

Transport of montmorillonite colloid and its associated Bismerthiazol in porous media

研究多孔介质中胶体及其携带污染物的运移规律,对于土壤污染物控制和污染土壤修复具有重要的意义。本文选用自然界存在矿物蒙脱石作为模型胶体,国内广泛应用的农药叶枯唑作为污染物,粒径150~200μm的石英砂作为多孔介质,采用三步法研究溶液中不同离子强度(IS 0.2、0.001 M)和pH(10、7、4)下叶枯唑以及不同离子强度(IS 0.1、0.01、0.001 M)下蒙脱石矿物胶体、蒙脱石和叶枯唑混合体在饱和多孔介质中的迁移和解吸。研究结果表明:碱性条件下(pH10)叶枯唑滞留较少,而在酸、中性条件下,滞留较为明显;离子强度对叶枯唑的滞留没有明显影响,相反对于蒙脱石胶体来说,随着离子强度的增大,蒙脱石滞留增加,并且当降低溶液的离子强度后,滞留的蒙脱石一部分会被重新释放出来;蒙脱石胶体和叶枯唑会相互促进其在多孔介质中的迁移,但滞留在多孔介质中叶枯唑并不会随着同样滞留的蒙脱石胶体的重新释放而释放。

Knowledge of the rule of the colloid and its carrying pollutant migration in porous media is of importance for the soil pollution control and the soil bioremediation a series of saturated column experiments were conducted with cleaned silica sand as porous media and natural montmorillonite as colloid and Bismerthiazol as contaminants which been widely used in China.It also includes three sets of experiments in this study.The first set of experiments was designed to examine the effects of ionic strength and pH on Bismerthiazol transport in porous media withoutcolloids.The second and third set of experiments investigated the montmorillonite colloid and montmorillonite colloid-associated Bismerthiazol retention and released in saturated porous media at different ionic strength(0.001,0.01,0.1 M).A two-and three-step procedure was used in these experiments.Results show that Bismerthiazol retention decreased with pH increased in porous media and its retention was obviously at acid and neutrality conditions;ionic strength has no significant effect of Bismerthiazol retention in porous media,however,the effects of ionic strength on montmorillonite colloid transport is obviously.As ionic strength increased the retention of montmorillonite decreased and some retained colloid would be released after solution ionic strength decreased;montmorillonite colloid and Bismerthiazol could be facilitated for each other when they transport in porous media,but the retained Bismerthiazol could not detached as montmorillonite released.