Levich equation

The Levich Equation models the diffusion and solution flow conditions around a rotating disk electrode (RDE). It is named after Veniamin Grigorievich Levich who first developed an RDE as a tool for electrochemical research. It can be used to predict the current observed at an RDE, in particular, the Levich equation gives the height of the sigmoidal wave observed in rotating disk voltammetry. The sigmoidal wave height is often called the Levich current.

The Levich Equation is written as:

I_L = (0.620) n F A D^\frac{2}{3}  w^\frac{1}{2}v^\frac{-1}{6}C

where

Note: To use the equation as written above (with the leading 0.620), certain units must be used with the parameters listed (e.g. radians per second for angular rotation, NOT radians or revolutions per minute). If revolution (rotations) per minute (rpm) are used, a value of 0.201 should be used in place of 0.620.

While the Levich equation suffices for many purposes, improved forms based on derivations utilising more terms in the velocity expression are available.[1][2]


References

  1. John Newman, J. Phys. Chem., 1966, 70 (4), 1327-1328
  2. Bard, Allen J.; Larry R. Faulkner (2000-12-18). Electrochemical Methods: Fundamentals and Applications (2 ed.). Wiley. p. 339. ISBN 0-471-04372-9.
This article is issued from Wikipedia - version of the Tuesday, December 08, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.