Simulation studies on a rotating ring disk electrode system: Role of supporting electrolyte in determination of relevance of ionic migration

Most of the past theoretical works with the rotating ring disk electrode (RRDE) system have been restricted to situations where supporting electrolyte concentration is large enough so that the effects of migration of ionic species in the solution becomes negligible. In this work, effects of ionic migration have been investigated for a RRDE system by solving the differential equations describing mass transfer in presence of ionic migration using numerical technique. Two cases were considered for simulation, presence and absence of migration of ionic species. Results indicate that in presence of migration, collection efficiency of a RRDE system increases for all electrode geometries and concentration boundary layer thickness reduces. Results also indicate that collection efficiency is dependent on electrode geometries. The system chosen for simulation is copper sulfate solution of 0.1 (M) concentration with little supporting electrolyte. It is also noticed that migration effect remains important for supporting electrolyte concentration as high as 0.1 (M). Limiting current condition was assumed. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1390–1399, 2013