Electrochemistry Module Updates

For users of the Electrochemistry Module, COMSOL Multiphysics® version 5.3 brings a new Electrophoretic Flow interface, new features in the Tertiary Current Distribution, Nernst-Planck interface, and a new Circuit Terminal feature to connect battery models with circuit simulations. Read more about these Electrochemistry Module updates below.

New Electrophoretic Transport Interface

The new Electrophoretic Transport interface can be used to investigate the transport of weak acids, bases, and ampholytes in aqueous solvents. The physics interface is typically used to model various electrophoresis modes, such as zone electrophoresis, isothachophoresis, isoelectric focusing, and moving boundary electrophoresis, but is applicable to any aqueous system involving multiple acid-base equilibria.

 

Zone electrophoresis separating a mixed sample of two proteins into two well-resolved concentration peaks.

New Tutorial: Zone Electrophoresis

This tutorial serves as an introduction to the Electrophoretic Transport interface. A zone electrophoresis problem is set up for separation of a sample containing aniline and pyridine.

Application Library path for the Zone Electrophoresis tutorial:
Chemical_Reaction_Engineering_Module/Electrokinetic_Effects/zone_electrophoresis

Ion-Exchange Membrane Internal Boundary Condition in the Tertiary Current Distribution, Nernst-Planck Interface

The new Ion-Exchange Membrane boundary node specifies a boundary condition where the flux of ions is continuous, but where the electrolyte potential is discontinuous and is described by a Donnan equilibrium. This condition is typically used in electrochemical cells containing both free electrolytes and ion-exchange membranes, for instance, in dialysis problems. A Donnan potential shift over the interface is calculated automatically from the concentrations of the charge-carrying ion on each side of the interface.

An electrolyte potential plot for a vananadium redox flow battery. Electrolyte potential in a vananadium redox flow battery showing the potential shifts at the interfaces between the free electrolyte and the ion-exchange membrane. Electrolyte potential in a vananadium redox flow battery showing the potential shifts at the interfaces between the free electrolyte and the ion-exchange membrane.

Application Library path for the updated Vanadium Redox Flow Battery model:
Batteries_&_Fuel_Cells_Module/Flow_Batteries/v_flow_battery

New Charge Conservation Models in the Tertiary Current Distribution, Nernst-Planck Interface

The Tertiary Current Distribution, Nernst-Planck interface now supports four different charge conservation models: electroneutrality, water-based with electroneutrality, supporting electrolyte, and Poisson.

Circuit Terminal Condition

You can use the Circuit Terminal feature on a boundary to specify a coupling to the External I Vs. U node in the Electrical Circuit interface from the AC/DC Module. The Circuit Terminal condition is now also available as a boundary condition in the Electrode Surface node and as an operation mode in the Single Particle Battery interface. This allows you to include high-fidelity battery models in circuit simulations.

Updated Tutorial: Isoelectric Separation

This example applies the Electrophoretic Transport and Laminar Flow interfaces to model isoelectric separation in a free-flow electrophoresis device. A stream containing four different proteins separates into concentrated streams by means of migrative transport in an electric field.

A plot from the Isoelectric Separation tutorial model, updated with COMSOL Multiphysics version 5.3. Concentration distribution of the proteins at the outlet of the device. Concentration distribution of the proteins at the outlet of the device.

Application Library path for the updated Isoelectric Separation tutorial model:
Chemical_Reaction_Engineering_Module/Electrokinetic_Effects/isoelectric_separation