Colloid generation during batch leaching tests: mechanics of disaggregation
Colloid generation during batch leaching tests: mechanics of disaggregation
复制标题
DOI：
10.1016/s0927-7757(97)00248-3
复制
发表时间：
1998-04-15
影响因子：
5.2
通讯作者：
Grasso, D
中科院分区：
文献类型：
--
作者：
Bergendahl, J;Grasso, D
批量浸出试验通常用于评估土壤中各种有机和无机污染物的浸出潜力。毒性特性浸出程序（TCLP）是由美国环境保护署开发的一种批量浸出试验，它采用了一种强力混合技术，可以使胶体组分出现在滤液中。本研究量化了煤焦油污染土壤在TCLP测试过程中胶体组分的产生，并探讨了其分解机制。颗粒计数数据表明，滤液中0.72和0.83 μ m直径的胶体浓度随着搅拌时间的增加而增加。测定了搅拌容器中的剪切速率，以及附着在土壤颗粒上的0.72和0.83 μ m胶体所受的水动力。通过使用力和力矩平衡，以及Johnson-Kendall-Roberts和Derjaguin-Muller-Toporov粘附模型，根据接触半径和静摩擦系数，确定了手术脱离机制最有可能是滚动或滑动。在TCLP测试过程中，胶体的产生导致滤液中总胶体表面积的增加，并可能同时导致对疏水污染物水相浓度的高估。(C) 1998爱思唯尔科学有限公司
Batch leaching tests are commonly used to assess the leaching potential of various organic and inorganic contaminants from soil. The toxicity characteristic leaching procedure (TCLP), a batch leaching test developed by the U.S. Environmental Protection Agency, employs an aggressive mixing technique that may allow colloidal fractions to appear in the filtrate. This study quantified the generation of colloid fractions during TCLP testing of a coal-tar contaminated soil, and explored the mechanics of disaggregation. Particle count data indicated that the concentration of 0.72 and 0.83 mu m diameter colloids in the filtrate increased with agitation time. The shear rate in the agitation vessel was determined, as well as the hydrodynamic forces acting on the 0.72 and 0.83 mu m colloids attached to the soil grains. Through use of force and moment balances, and the Johnson-Kendall-Roberts and Derjaguin-Muller-Toporov adhesion models, it was determined that the operative detachment mechanism is most likely rolling or sliding, depending on the contact radius and the coefficient of static friction. Colloid generation during the TCLP test results in an increase in total colloidal surface area in the filtrate, and may concomitantly result in an overprediction of the aqueous phase concentration of hydrophobic contaminants. (C) 1998 Elsevier Science B.V.