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

从悬浮液中分离出具有高度特殊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，需要以工业上的相关量来分离尺寸为&lt；10μm且不同性质的细小分散的多组分颗粒混合物，仅由于一种分离特性而进行的分级不再是足够的。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级”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错流过滤工艺。这一过程代表了一种具有微米和亚微米(&lt；10微米)颗粒的高度特定的悬浮液分离方法。分离是在流体动力和电泳力的帮助下进行的。提升力和电泳力导致在过滤器区域前面的流动通道中对颗粒进行预分类。之后，由于滤失率的作用，在开孔过滤介质上发生实际的分馏。研究项目的目的是进一步发展和推广新方法，该方法在第一个资助期进行了研究。重点考察了工艺参数(流速、压差和电场强度)和材料体系(颗粒形状、组成、电位变化添加剂)对分离流体力学和电泳当量直径的影响。通过对错流过滤过程中颗粒运动的实验研究和数值模拟，从颗粒的大小、形状和电泳率三个方面对错流过滤过程中的颗粒分离进行了描述，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耦合进行了数值模拟，提供了局部颗粒动力学和流体动力学的信息，为宏观尺度上的整体过程模拟提供了参数。必须进行该工艺的放大，以提供技术上相关数量的高度特定的超细颗粒悬浮液。

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.