Divalent Metal Ion Depletion from Wastewater by RVC Cathodes: A Critical Review

In this paper, a critical review of results obtained using a reticulated vitreous carbon (RVC) three-dimensional cathode for the electrochemical depletion of various divalent ions, such as Cu⁺², Cd⁺², Pb⁺², Zn⁺², Ni⁺², and Co⁺², often present in wastewater, has been carried out. By analyzing the kinetics and fluid dynamics of the process found in literature, a general dimensionless equation, Sh = f(Re), has been determined, describing a general trend for all the analyzed systems regardless of the geometry, dimensions, and starting conditions. Thus, a map in the log(Sh) vs. log(Re) plane has been reported by characterizing the whole ion electrochemical depletion process and highlighting the existence of a good correlation among all the results. Moreover, because in recent years, the interest in using this three-dimensional cathode material seems to have slowed, the intent is to revive it as a useful tool for metal recovery, recycling processes, and water treatments.