Theoretical Background to ED in Flowing Liquid Streams

This section deals with the particular aspects of electrochemistry relevant to flowing systems. An introduction to the background of the theory was given in the previous chapter, and more detailed descriptions of the theoretical aspects can be found elsewhere.  

In outline, an EC reaction, at a solid surface electrode over which a liquid stream is flowing, is characterised by the following three separate and distinct stages  

Diffusion of the reaction product(s) away from the electrode surface 

Schematic diagram of the electrode processes occurring when, in this case, a reduced analyte flows over a static electrode held at an appropriate voltage. 

The diffusion equation (Pick s second law) describes the rate of change of the analyte concentration above any planar surface. This analyte flux is proportional to the diffusion coefficient of the analyte (D). The flux therefore governs the limiting current (/nm) and is directly proportional to the surface area of the electrode and analyte concentration (C) and inversely proportional to the thickness (8) of the diffusion layer  

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