题目：Filtration and Transport of Colloids and Nanoparticles in Dense Emergent Vegetation: Theory, Experiment, & Modeling

报告人：Lei Wu

时 间：1月7日（周一）下午1：30
地 点：方正大厦301会议室
主持人：张东晓（教授）

报告内容摘要：
    Thorough understanding of filtration and transport of colloidal contaminants in aquatic environment is of great importance to many environmental and biological processes. However, little research has been conducted to investigate the transport of colloidal particles through emergent vegetation in overland flow. In this work, a series of systemic laboratory experiments were conducted to measure the single-stem contact efficiency (η0) and attachment efficiency (α) of colloid capture by a simulated plant stem in laminar lateral flow. The results showed that existing theoretical and empirical models of colloid contact and attachment efficiency for porous media were found to fall short in describing the colloid filtration by dense vegetation system in overland flow.  New dimensionless equations of single-stem efficiencies were developed to predict colloid filtration by dense vegetation with reasonable accuracy. Except colloidal particles, the ever-increasing use of engineered nanomaterials (e.g. carbon nanotubes (CNTs)) will lead to heightened levels of these materials in the environment. CNTs aggregation and deposition behavior will dictate its transport potential and thus the environmental fate and potential ecotoxicological impacts of these materials. However, the unique properties of CNTs proposed challenges in experimentally and theoretically quantifying its deposition and aggregation in the environment. The surface element integration (SEI) technique was coupled with the DLVO theory to determine the orientation-dependent interaction energy between CNTs and an infinite isotropic planar surface. For the first time, analytical formula was developed to accurately describe the interaction between not only pristine but also surface charged CNTs and planar surfaces with arbitrary rotation angles. The new analytical expressions presented in this work can be used as a robust tool to describe the DLVO interaction between CNTs and planar surfaces under various conditions and thus to assist the design and application of CNT-based products.