Multidimensional fractionation of finely dispersed particles using cross-flow filtration with superimposed electric field

从悬浮液中分离具有高度特定物理性质的颗粒组分在许多工程过程中具有重要意义。在许多应用中，粒度<10 μm且不同性质的颗粒的精细分散的多组分混合物需要以工业相关的数量进行分离，仅依靠一种分离特性进行分选已不再足够。在DFG优先计划SPP 2045“具有技术相关性的细颗粒系统的高度特异性和多维分馏”的框架内，在第一个资助期开发了一种具有叠加电场的新型交叉流过滤工艺。该工艺代表了一种与微和亚微米颗粒（< 10微米）高度特异性分离悬浮液的方法。分馏是在流体动力和电泳力的帮助下进行的。升力和电泳力导致过滤区前面的流道中的颗粒进行预分类。在此之后，实际的分馏作用在开孔过滤介质上，由滤液速率产生的阻力作用。该研究项目的目的是进一步发展和升级新方法，该方法在第一个资助期进行了研究。研究的重点是工艺参数（流速、压差和电场强度）和材料系统（颗粒形状、组成、电势变化添加剂）对分馏流体动力和电泳等效直径的影响。通过对颗粒运动的实验研究和辅助模拟，从粒径、形状和电泳迁移率三个方面描述了颗粒在横流过滤过程中的分离，从而确定了最佳参数范围。为了获得分离过程的附加参数，采用了多尺度建模方法。在微观尺度上，利用CFD-DEM耦合方法进行了模拟，提供了局部颗粒动力学和流体动力学信息，并为宏观尺度上的整体过程模拟提供了参数。该工艺的升级必须执行，以提供技术上相关数量的高度特异性超细颗粒悬浮液。

The separation of particle fractions with highly specific physical properties from suspensions has a great importance in numerous engineering processes. In many applications, in which finely dispersed multicomponent mixtures of particles with sizes <10 μm and different properties are to be separated in industrially relevant quantities, the fractionation due to only one separation characteristic is no longer sufficient. Within the framework of the DFG Priority Program SPP 2045 " Highly specific and multidimensional fractionation of fine particle systems with technical relevance", a novel cross-flow filtration process with superimposed electrical field was developed in the first funding period. This process represents a method for the highly specific separation of suspensions with the micro and submicron particles (< 10 microns). The fractionation is performed with the help of hydrodynamic and electrophoretic forces. The lift forces and electrophoretic forces cause a pre-classification of the particles in the flow channel in front of the filter area. After that the actual fractionation takes place on the open-pore filter medium by the drag forces acting due to the filtrate rate. The aim of the research project is the further development and the upscaling of the new method, which was studied in the first funding period. The focus of the investigations is on the influence of the process parameters (flow velocity, pressure difference and electric field strength) and the material system (particle shape, composition, additives for potential change) on the hydrodynamic and the electrophoretic equivalent diameter of the fractionation. By means of experimental investigations and supporting simulations of the particle movement in the flow, the particle separation during cross-flow filtration is described in terms of size, shape and electrophoretic mobility and thus the optimal parameter ranges are determined. To obtain additional parameters of the separation process, a multiscale modeling approach is used. On the microscale, the simulations using CFD-DEM coupling are performed, which provide information on the local particle dynamics and hydrodynamics and provide the parameters for the simulation of the overall process on the macro scale. The upscaling of the process has to be performed to provide technically relevant quantities of highly specific ultrafine particle suspensions.