Magnetic Separation - A computer simulation study

Abstract

Nanotechnology which involves magnetic particles has experienced, in the last decades, an impressive boost and magnetic nanoparticles have become an interesting research area on their own, finding applications in a rather broad range of techniques and devices, from waste-water treatment to new clinical and biomedical applications. Most notably, they occupy a relevant role in the framework of magnetic separation technology. However, due to their minute size, the actual separation of the magnetic nanoparticles from the solution in which are suspended constitute a real challenge: the separation problem. Understanding the basic mechanisms behind the separation of a dispersion of magnetic nanoparticles subjected to an external field would provide an advance toward the solution of the problem. However, such good understanding is still missing. In this thesis, we describe our implementation of a simulation algorithm capable of modeling a High Gradient Magnetic Separation (HGMS) process of magnetic nanoparticles in a continuous flow. The simulations are customized to model a separation column made of a random packing of ferromagnetic rods, which is a novel idea in the framework of HGMS. The simulation project is intended to provide a theoretical counterpart to the experiments which are performed in a custom setup at the Physical and Colloid Chemistry Laboratory (FCC) at Utrecht University. The study aims to determine the optimal configuration in terms of tunable parameters (strength and orientations of the external magnetic field, flow conditions, packing of the rods, etc.). In order to achieve the main result, an exact expression of the magnetic field generated by the separation matrix is needed. A set of analytical equations describing the magnetic field of a magnetic rod uniformly magnetized in an arbitrary direction have been derived for the purpose.