# Nernst-Planck equation

The **Nernst-Planck equation** , after the physicists Walther Nernst and Max Planck , describes the movement of ions taking into account the electrical field .

Formally the equation for the ion current is :

With

- the diffusion coefficient
- the Nabla operator
- of concentration
- the valence
- the external electric field strength
- the Boltzmann constant
- the absolute temperature .

The Nernst-Planck equation is particularly important for the theory of electrophoresis . More generally, it plays a major role in the description of non-equilibrium states of charged systems in electrolyte solution .

## literature

- Gerold Adam, Peter Läuger, Günther Stark: Physical chemistry and biophysics . 5th edition. Springer, 2009, ISBN 978-3-642-00424-7 , Chapter 8.4: Nernst-Planck equation and diffusion potential.