Microscopic particle interactions in surfacefiltration processes (MicSurF)

在表面过滤过程中，过滤后的颗粒在膜表面积聚，增加了水力阻力，降低了整体工艺性能。传统的压力通量分析缺乏对滤饼形貌和颗粒特性对滤饼影响的认识。本课题将利用微流体原位可视化技术研究颗粒性质对滤饼形态和水动力过滤阻力的影响。首先，利用微流控停止流动光刻和连续双光子聚合制备出具有所需3d形状、尺寸分布、孔隙度和柔软度的3d颗粒。其次，用模拟膜的微流控电池对这些颗粒进行过滤，并用原位高分辨率共聚焦显微镜对滤饼进行分析。具有良好控制系统参数的精确模块设计将允许对单个粒子及其相互作用进行可视化和分析。第三，在微观观察的基础上，我们将在实验室规模的过滤池中验证微观现象，并分析其对相关工艺条件的影响，如饼的形成和饼的去除。在实验室规模的过滤池中对滤饼的研究在可视化过程中缺乏分辨率，但包括具有真实交叉流场和商用膜的真实工艺条件。本项目将对表面过滤过程中的滤饼有一个基本的微观认识。它将弥合微观颗粒性能和经验膜性能之间的差距。研究结果将有助于提高基于过滤系统物理性质的数学过滤模型的准确性。

In surface filtration processes the filtrated particles accumulate on the membrane surface, increase the hydraulic resistance, and reduce the overall process performance. The conventional pressure-flux analysis lacks of insights into the cake morphology and the impact of particle characteristics on the cake. In this project we will study the influence of particle properties on the filter cake morphology and the hydrodynamic filtration resistance using microfluidic in-situ visualization techniques. First, 3D-particles with desired 3D-shape, size-distribution, porosity, and softness are fabricated using microfluidic stop flow lithography and continuous two-photon polymerization. Second, these particles are filtered with membrane-mimicking microfluidic cell and the filter cake will be analyzed using in-situ high resolution confocal microscopy. A precise module design with well controlled system parameters will allow visualization and analysis of single particles and their interactions. Third, based on the microscopic observations, we will validate the microscopic phenomena in a lab scale filtration cell and analyze their influence on relevant process conditions, such as cake built up and cake removal. The investigation of filter-cakes in the lab scale filtration cell lacks in resolution during visualization, but comprises real process conditions with realistic cross-flow flow fields and commercial membranes. This project will give a fundamental micro-scale understanding of filter cakes in surface filtration processes. It will bridge the gap between microscopic particle properties and empirical membrane performance. The results will contribute to improve accuracy of mathematical filtration models which are based on physical properties of the filtration system.