Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei 106, Taiwan, ROC.
Environ Sci Technol. 2010 Dec 1;44(23):8996-9002. doi: 10.1021/es102191b. Epub 2010 Nov 10.
A new trajectory simulation algorithm was developed to describe the efficiency of a single collector (pore) to catch submicrometer particles moving through saturated porous media. A constricted-tube model incorporating the deterministic (interception, hydrodynamic retardation, van der Waals force and gravitational sedimentation), stochastic (Brownian diffusion), and thermodynamic (electrostatic and steric repulsion force) mechanisms was established to predict the transport and deposition of surface modified nanoscale zerovalent iron (NZVI) particles by applying Lagrangian trajectory analytical approach. The simulation results show good agreement with the results predicted by existing energy-barrier-free models except for the particle size less than 100 nm at low approach velocity. The number of realizations per start location could be decreased down to 100 with the simulations still exhibiting acceptable relative standard deviation for engineering purposes. With the consideration of energy barriers, the model successfully describes the breakthrough curve of polymer-modified NZVI in a benchtop soil column as well. The novel simulation scheme can be a useful tool for predicting the behavior of the nanoscale colloidal particles moving through filter beds or saturated soil columns under conditions with repulsion and attraction forces among surfaces.
开发了一种新的轨迹模拟算法，用于描述单个收集器（孔隙）捕获通过饱和多孔介质中运动的亚微米颗粒的效率。建立了一个带有约束管模型，该模型结合了确定性（拦截、流体动力迟滞、范德华力和重力沉降）、随机（布朗扩散）和热力学（静电和空间排斥力）机制，以通过应用拉格朗日轨迹分析方法来预测表面改性纳米零价铁（NZVI）颗粒的传输和沉积。模拟结果与现有无能量障碍模型预测的结果吻合良好，除了在低接近速度下粒径小于 100nm 的情况外。对于工程目的，每个起始位置的实现次数可以减少到 100，而模拟仍然表现出可接受的相对标准偏差。考虑到能量障碍，该模型成功地描述了聚合物改性 NZVI 在台式土壤柱中的突破曲线。该新型模拟方案可以成为一种有用的工具，用于预测在排斥和吸引力作用下，纳米胶体颗粒通过过滤床或饱和土壤柱的运动行为。
