Electrochemical ozone production using electrolyte-free water for environmental applications

Oxide fine-mesh electrodes composed of lead dioxide doped with Fe3+ (OFM-Fe-PbO2) were prepared by electrodeposition onto a stainless-steel fine-mesh support in order to obtain fluid-permeable electrodes for an electrochemical filter-press reactor. These electrodes were used in electrochemical ozone production (EOP) carried out during the electrolysis of electrolyte-free water in order to obtain an environmentally friendly technology for the “in situ” water treatment. SEM images of electrodes prepared using different electrodeposition conditions showed the formation of well-defined crystalline grains, which uniformly covered the metallic wires of the support. X-ray analysis revealed that the formation of a β-PbO2 phase is more pronounced than the α-PbO2 phase. A maximum EOP current efficiency of 10%, obtained at j = 1.5 A cm−2, corresponding to a rate for the ozone generation of 1.58 g h−1 and a specific electric energy consumption of 0.250 kW h g−1, was attained for the OFM-Fe-PbO2 electrode formed using the electrodeposition bath containing 1.0 mM Fe3+. The performance of the electrochemical reactor was evaluated during long-term galvanostatic electrolysis (t = 60 days, j = 1.0 A cm−2 and 24 °C), during which it was verified that the reactor voltage (U) and EOP current efficiency (ΦEOP) were both stable. The robustness of the SPE filter-press electrochemical reactor allied to a moderate EOP current efficiency indicated that the OFM-Fe-PbO2 electrode (1.0 mM Fe3+) is promising for in situ ozone production from the electrolysis of electrolyte-free water.