Potential Oscillated Electrochemical Metal Recovery System with Improved Conversion Kinetics and High Levelized Quality.

Electrodeposition, which is an eco-friendly process with high efficiency, is one of the most promising technologies for metal recovery. However, the kinetics are often limited by the polarization and uncontrollable quality of deposits during the electrodeposition process, which restrict the efficiency and controllability of metal recovery. To ameliorate the limitations of the deposition rate and as-formed deposit quality, transient electrodeposition was introduced to control the microinterfacial reaction by regulating the relationship between charge and mass transfer. The Cu2+ removal efficiency and kinetic coefficient during 1 kHz transient electrodeposition were 17.4 and 17.7% higher than those under the conventional steady electric stimulus, respectively. Based on the combined results of X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS), it was found that the chemical composition of the deposits from transient electrodeposition was more homogenous, as indicated by the low content of metal oxides. The in situ Raman spectra explained the homogenous composition based on the weak interaction of the electrode with the anions during the transient electrodeposition, which was mainly due to the enhanced dehydration under the oscillating or alternating electric field. The potential oscillation induced by the transient electric field also facilitated dehydration, charge transport, and mass transfer, which led to rapid and high-quality metal recovery. Transient electrodeposition will have a great guidance value in the field of metal electroplating and heavy metal recovery from wastewater by electrodeposition.