Electrochemical recovery of tin from the activating solutions of the electroless plating of polymers: Galvanostatic operation

The performance of a two-compartment batch electrochemical reactor separated by a ceramic diaphragm for tin removal from the activating solutions in galvanostatic operation is studied in this paper. The effect of the applied current on the figures of merit (fractional conversion, current efficiency, space-time yield and specific energy consumption) of the electrochemical reactor is analysed. As the applied current increases, current efficiency (ϕ) for tin recovery decreases due to the hydrogen-reduction side reaction, which causes an increment in the specific energy consumption (Es). On the other hand, the greater the applied current, the higher the values of both tin fractional conversion (X) and space-time yield (η) because of an increase in the mass transfer coefficient because of the hydrogen turbulence-promoting action and in the electrode area roughness.Sn(II) formation resulting from Sn(IV) electrochemical reduction as a function of the applied current is also evaluated. When the applied current is higher than the limiting current, the electrode potential is of about −1 V, and the concentration of Sn(IV) ion considerably decreases, the stannous ion formation has been observed.