A mass transfer study of the electropolishing of metals in mechanically agitated vessels

Rates of electropolishing of vertical copper plates in H3PO4 were studied in a rectangular cell stirred by 4 blade 45° pitched turbine. Variables studied were impeller rotating speed, plate height and H3PO4 concentration. The limiting current density at which polishing takes place was found to increase with impeller rotation speed to the power of 0.44, increasing the plate height (L) was found to decrease the limiting current density (I) according to the equation: I = a L−0.24. The data were correlated under different conditions by the dimensionless equation Sh = 2.5 Sc0.33 Re0.44 (L/de)−0.24