Improving performance of proton-exchange membrane (PEM) electro-ozonizers using 3D printing

Ozone (O3) is a powerful oxidant widely used in disinfection and wastewater treatment. In this work, a novel 3-D printed casing for electrochemical cells has been specially designed and manufactured for Proton-Exchange Membrane (PEM) electro-ozonizers, trying to promote an improved fluid dynamic including an efficient evacuation of gases produced during the electrolysis and aiming to minimize the interaction among ozone and scavengers. It is demonstrated that reaching high efficiencies in the electrochemical production of ozone is limited by the action of electrogenerated scavengers, among which cathodically formed hydrogen peroxide outstands. This explains the effects observed regarding current density (higher efficiencies at higher current densities applied, because hydrogen peroxide production is prevented), electrolyte composition (better efficiencies with lower concentrations of non-reacting electrolytes) and operation pressure (better results at lower pressures, because hydrogen peroxide formation depends more importantly on dissolved oxygen than ozone production). A very good performance is obtained, with ozone productions as high as 0.240 mg/(Ah cm2) and maximum current efficiencies of 5.9% under the best operation conditions (1.0 mM of HClO4, 330 mA/cm2 and 1 bar), which demonstrate the suitability of the technology tested and the good perspectives of 3D printing to improve performance of electrochemical processes.