Unravelling transport and deposition mechanisms of virus-like colloids during depth filtration

膜深度过滤在病毒过滤、污染物去除等方面有着广泛的应用。深度过滤的性能通常受到渗透性和保留率之间权衡的限制。对胶体和颗粒传输以及它们在多孔介质深处的沉积现象的基本了解是非常重要的。描述深度过滤性能的各种研究要么是通过宏观可测量的穿透曲线和通量-压力图，要么是通过过滤后膜的微观分析。传输和沉积现象是基于这些粗略的宏观测量而假设的。然而，基本的输运和沉积现象仍然缺乏微观的实验分析和验证，许多现象，如胶体和颗粒的形状和变形性的作用，它们的再悬浮，以及表面特性的影响，都只是知之甚少。无法非侵入性地实时监测多孔介质内的这些现象，这是迄今为止传输和沉积现象仍然缺乏微观了解的关键限制。本项目将通过(A)胶体和多孔过滤器结构的微工程，以及(B)先进的可视化方法，如微粒子速度计、荧光寿命成像(Flim)和共聚焦显微镜，原位表征多孔介质内的微观传输和沉积现象。这种方法使我们能够解开运输和沉积现象之间复杂的相互作用。他们的实验观察使我们能够对深度过滤过程中的捕获过程有一个基本的了解，并建立了与真实膜过滤器性能相关的微观事件的分类。与我们正在进行的模拟活动相辅相成的是，这些知识将是弥合微观胶体领域和宏观过滤世界之间差距的先决条件。

Membrane-based depth filtration is widely applied e.g. in virus filtration and contaminant removal. The performance of depth filtration is commonly limited by the trade-off between permeability and retention. A fundamental understanding of colloid and particle transport as well as their deposition phenomena in the depth of the porous medium is of fundamental interest. A variety of studies exist describing the performance of depth filtration by either macroscopic measurable breakthrough curves and flux-pressure diagrams or by the microscopic analysis of the membrane after filtration. Transport and deposition phenomena are hypothesized, based on these crude macroscopic measurements. However, the fundamental transport and deposition phenomena still lack a microscopic experimental analysis and validation.Many phenomena such as the role of shape and deformability of the colloid and particles, their resuspension, and the influence of surface characteristics are only poorly understood. The inability to monitor non-invasively in real-time these phenomena inside the porous media represents the key limitation of why the transport and deposition phenomena still lack microscopic understanding so far.This project will in-situ characterize the microscopic transport and deposition phenomena inside porous media by (a) micro-engineering of both the colloids as well as the porous filter structures integrated with (b) sophisticated visualization methods such as micro Particle Velocimetry µPIV, Fluorescent Lifetime Imaging (FLIM), and confocal microscopy. The methodology enables us to deconvolute the complex interplay between transport and deposition phenomena. Their experimental observation allows a fundamental understanding of the capture process during depth filtration and establishes a classification of microscopic events that can be related to real-life membrane filter performance. Complemented with our ongoing simulation activities, this knowledge will be a prerequisite to close the gap between the microscopic colloidal domain and the macroscopic filtration world.