h i g h l i g h t s Efficient removal strategies for microplastics are lacking. Magnetic seeded filtration showed high separation efficiencies ($95%) for dilute suspensions. Electrostatic interactions between particles were shown to be process determining. A parameter study identified relevant process variables and yielded clear application guidelines. The measurement of agglomeration kinetics enables further optimization.

The main goal of this work is to develop and validate a new method for characterizing the material properties of hetero-agglomerates when calculating population balances in magnetic seeded filtration processes. A new approach of computing various collision cases and probabilities and then weighting the respective agglomeration rates with them is considered to be physically justifiable. An experimental design of experiment (DOE) yielded data for the variation of multiple process parameters with a reasonable standard deviation. By measuring agglomeration kinetics, a deeper understanding of the process could be achieved and simple mathematical models were found in order to describe experimental data. The following multiple regression analysis showed good accordance with the agglomeration theory and thus the data was usable for further validation of the calculation results. By comparing calculated and experimental data and minimizing the residuals, estimates of the model parameters describing hard-to-measure material properties could be obtained. The comparison of experimental and computational regression models showed good agreement and thus validates the fundamental physical soundness of the implemented model. Furthermore, the comparison of the measured and calculated agglomeration kinetics further suggests the validity of the collision case model. Finally, this work showcases the possibilities of additional model calculations for a deeper, more thorough process understanding.

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.

An innovative magnetic filter in combination with a Mandhala magnet for oil filtration processes has been developed. With this filter design also nonmagnetizable particles can be separated. Responsible are hetero agglomeration processes that arise due to agglomeration of magnetizable with nonmagnetizable particles. Separation efficiencies in dependence of the particle size distribution and particle shape are quantitatively determined. An evaluation method for the quantification of the separation efficiency of nonmagnetizable particles is developed and validated by experimental data. On this basis, a statement about the efficiency of the hetero agglomeration can finally be made.

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