Opportunities and Challenges of Magnetic Seeded Filtration in Multidimensional Fractionation

Abstract

This study examines the general applicability of magnetic seeded filtration (MFS) for the fractionation of complex particulate systems by multiple particle features. Experimental studies on a laboratory scale showed that especially the electrostatic interactions govern the separation process. Furthermore, a clear size dependency could be shown, as the separation efficiency decreases with increasing size of target particles. Since MSF is both surface‐ and size‐dependent, it is generally applicable in a multidimensional fractionation. Finally, the challenges to be overcome are addressed as well.

Separation of Microplastic Particles from Sewage Sludge Extracts Using Magnetic Seeded Filtration

“…Increasing the ionic strength by a factor of 100 from to did not significantly change the separation efficiency ( Fig. 2 ), which is in contrast to previous studies on MSF ( Rhein, Ruß, Nirschl, 2019 , Rhein, Scholl, Nirschl, 2019 , Rhein, Schmid, Esquivel, Nirschl, 2020 ). At all investigated particle systems are expected to be negatively charged (see Section 2.6 ), resulting in an electrostatic repulsion.…”

“…The independence of the separation efficiencies from the ionic strength, therefore, suggests that the compression of the electric double layer did not change the aggregation behavior and that therefore, electrostatic forces were not controlling the hetero-aggregation process. Based on the results from previous studies Rhein, Ruß, Nirschl, 2019 , Rhein, Schmid, Esquivel, Nirschl, 2020 , Rhein, Scholl, Nirschl, 2019 , only a negligible repulsion is expected at . The fact that this did not lead to an increase in the separation efficiency (in the experiments conducted with pristine magnetite), therefore indicates that the van der Waals attraction between particles is too weak to induce an agglomeration.…”

“…The most plausible explanation for this phenomenon is found in the particle diameters, which are orders of magnitude larger than in Rhein, Ruß, Nirschl, 2019 , Rhein, Schmid, Esquivel, Nirschl, 2020 , Rhein, Scholl, Nirschl, 2019 : Whereas the van der Waals interaction increases proportionally to the particle radius , inertial forces or flow effects increase proportionally to the volume of the particle, i.e. .…”

“…However, potential interactions between cellulose and MP may lead to an increase in the separation of cellulose and, thus, a reduced selectivity. A detailed discussion about selectivity in multi-component agglomerating systems is given in ( Rhein et al., 2020 ). In the 3-component system, cellulose and MP can be present in the separated fractions.…”

On the acoustically induced fluid flow in particle separation systems employing standing surface acoustic waves – Part II

“…The active manipulation of the motion of suspended microparticles or biological cells is essential for a broad variety of applications ranging from process technologies to life science. 1–3 In recent years, the systematic utilization of magnetic, 4–6 electric 7–9 and acoustic fields 10,11 in microfluidics has enabled the development of highly customized technologies for concentrating, 12,13 patterning, 14–16 mixing 17–19 or sorting 1,20–22 particle solutions in a flexible and scalable environment. Among these technologies, the on-chip integration of surface acoustic waves (SAWs) represents a non-invasive, label-free, biocompatible and versatile method for the precise manipulation of suspended matter through local force fields.…”