Electrolytic removal of Ni and Co ions from exhausted solutions

The removal of Co(II) and Ni(II) ions from sulfate exhausted solutions at pH 6-6.5 has been investigated in an electrochemical reactor with a reticulated vitrous carbon cathode and a platinated titanium net anode. After determining for both Ni(II) and Co(II) the values of cathodic potential for which the electrowinning process is mass-transfer limited, the performance of the cell were determined for catholyte flow rate up to 1.6 l/min. Dimensional analysis was performed to individuate the design equation to scale-up the electrochemical reactor. The electrochemical reactor behaves in a different manner for the two metal ions studied. This behavior is probably due to the different deposit morphology of the two metals that produces their different specific surface area and catholyte speed.