Dielectrophoretic Particle Chromatography (DPC) with scalable separation effect at preparative scale

• Applicant: Dr. Michael Baune, since 7/2022
• Subject Area: Mechanical Process Engineering
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 382065007

The separation of micron and submicron particles from a liquid medium or their fractionation according to specific properties is essential for a variety of applications. Particle separation is key, for instance, in (bio-) analytics, medical diagnostic, material recycling, product quality enhancement, or to improve the cost efficiency of industrial processes. As an example, to recover precious metals from scrap, the scrap is firstly milled to produce smaller pieces that could be separated with standard methods according to density, magnetism, or other properties. Most of the precious metal, however, is concentrated in the fine dust that is produced as a byproduct and which is too small for an effective fractionation. Standard methods to sort such small submicron or micro particles are for example gel electrophoresis or size exclusion chromatography. These methods, however, can only process small quantities per batch and the recovery of the resulting fractions is intensive in both cost and time. This effectively limits those techniques to analytical application. Other continuous fractionation approaches for higher throughputs, such as field flow fractionation or centrifugation lose both selectivity and efficiency when processing particles smaller than 10 µm. Here, dielectrophoretic particle chromatography is introduced. This methods uses dielectrophoresis, an ac electrokinetic effect, to increase the residence time of target particles according to specific properties in a chromatography column: Particle mixtures will interact with a superimposed inhomogeneous ac electric field differently according to their polarizability, which is a particle property that depends on particle form, size and material. The inhomogeneous ac field is created by two concentric electrodes which form an annulus. The annulus is filled with a dielectric packed-bed (e.g., of quartz spheres) that scatters the electric field of the concentric electrodes and creates local inhomogeneities. Such an arrangement allows for several orders of magnitude higher throughput compared to conventional microfluidic dielectrophoretic separators. The applied ac field is modulated in its frequency in order to target specific differences in the frequency-dependent particle polarizability. To better understand the underlying transport mechanisms and to design a dielectrophoretic chromatography column that can operate at industrially relevant throughputs, both microchannels as well as macroscopic packed-bed columns will be investigated. A detailed parameter variation study (regarding applied field strength, frequency, packing and channel geometry, as well as modulation frequency) will be conducted using both simulation and experimental methods. Aim of this project is the implementation of a dielectrophoretic chromatography column for a continuous multi-dimensional fractionation of particles in the liquid phase at throughputs of up to 10 g per hour.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2045: Highly specific and multidimensional fractionation of fine particle systemes with technical relevance
• Ehemaliger Antragsteller: Professor Dr.-Ing. Georg Pesch, until 6/2022