Electrochemical wall mass transfer in liquid particulate systems

Ionic mass transfer coefficients between the wall of a 2.081 inch tube and liquid fluidized beds of lead glass, soda glass and lucite spheres have been measured using the diffusion‐controlled reduction of ferricyanide ion at a nickel cathode for porosities 0.90 to 0.45 and Schmidt numbers 580 to 2100. The developed fluidization mass transfer coefficient for 41 < D T /d p < 105 were correlated by i D E = 0.274 Re H −0.38 for 10 < Re H <1600 and by J D E = 0.455 Re H −0.44 for 16.7 < D T /d p < 27 and 50 < Re H < 3500. Re H is the hydraulic Reynolds number = d H u p /μ E and d H is D T E/[1 + (3/2) ((1–E)) (D T /d p )). The distinct effect of D T /d p ratio is attributed to wall effects and the non‐particulate behaviour of the fluidized bed for D T /d p < 27. Measurements in the open pipe and packed bed agreed very well with literature values. The packed bed gives highest mass transfer coefficients at given Re H .