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

基于膜的深度过滤广泛应用于例如病毒过滤和污染物去除。深层过滤的性能通常受到渗透性和保留性之间的权衡的限制。对胶体和颗粒的输运以及它们在多孔介质中的沉积现象有一个基本的了解是至关重要的。通过宏观可测量的穿透曲线和通量-压力图或通过过滤后膜的微观分析，存在描述深层过滤性能的各种研究。运输和沉积现象的假设，根据这些粗糙的宏观测量。然而，基本的输运和沉积现象仍然缺乏微观实验分析和验证，许多现象，如胶体和颗粒的形状和变形能力的作用，它们的再悬浮，以及表面特性的影响，只是知之甚少。无法实时非侵入性地监测多孔介质内的这些现象是迄今为止对传输和沉积现象缺乏微观理解的关键限制。本项目将通过（a）胶体和多孔过滤器结构的微观工程与（B）先进的可视化方法，如微粒子测速法µPIV、荧光寿命成像（FLIM）和共聚焦显微镜。该方法使我们能够解卷积运输和沉积现象之间的复杂的相互作用。他们的实验观察允许对深层过滤过程中的捕获过程进行基本了解，并建立了可能与实际膜过滤器性能相关的微观事件分类。补充我们正在进行的模拟活动，这方面的知识将是一个先决条件，以关闭之间的差距差距微观胶体域和宏观过滤世界。

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.