Development of a multi-scale model for the adsorption of molecular target substances to magnetic carrier particles using the Lattice-Boltzmann methods

• Applicant: Privatdozent Dr. Mathias Joachim Krause
• Subject Area: Mechanical Process Engineering
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 256075891

Biotechnology is considered a key technology for the production of pharmaceuticals, specialty chemicals and food. Many pharmaceutical products are produced by expression in genetically modified bacteria or cells. Thereby, the separation of the desired products from fermentation broth plays an important role. The separation process is difficult. Besides the target protein, there are different contaminating proteins which behave similarly and which are separated only by means of highly selective methods taking advantage of differences in isoelectric point or specific binding sites. Magnetic particles with functionalized surface are an efficient option for the separation. Currently there are no detailed investigations of the adsorption process and its influence on the whole separation process, specifically on the maximum volume flow. However, they are necessary to develop efficient procedures for industrial use.The aim of the project is to investigate the process of adsorption and separation of molecular target substances on magnetic functionalized particles. The different physical phenomena in different orders of magnitude (adsorption, inter-particular effects and separation from fluid) are challenging concerning modeling as well as simulation. The process is usually described separately by micro- and macroscopic models and coupled via boundary conditions. The relationships are complex and have not been described in a single approach. Due to high computational costs simulations were limited both locally to small areas and partially to sub-processes. In the proposed project, the physical phenomena are linked by mesoscopic modeling using Lattice Boltzmann methods (LBM) for simulation. Thus, the model to be developed links molecular phenomenon in Ångström scale with macroscopic fluid effects as well as their influence on the particle motion in the mm scale. A common approach is the microscopic description of particle dynamics, discretized by a Discrete Element Method, and a macroscopic model, discretized by a Finite Volume Method. The new approach allows a more efficient simulation and thus the simulation of a larger geometric scale, including the entire separation apparatus. The modeling approach of the calibration and validation takes place by simulation of adsorption processes in a static mixer. Then the model is reduced with sensitivity-based approaches, the process is simulated on a modern magnetic separator and experimentally validated. To final Euler-Euler-Euler model is transferable and may be used for other multi-scale issues like e.g. the simulation of photo- bioreactors in the future.

• DFG Programme: Research Grants
• Participating Person: Professor Dr.-Ing. Hermann Nirschl