Anode for electrochemical ozone generation electrolyte-free water and effect this electrode to decrease COD

Ozone is an environmentally- friendly oxidant that is widely used for industrial applications, such as water disinfection, air purification, and medical use [۱]. Ozone that kills microorganisms, decomposes organic molecules, and removes unwanted components including coloration, cyanide, phenols, iron, and manganese. It can be used to disinfect portable water, food, surgical equipment, and sewage[۱]. Ozonation was carried out for COD removal of water [۲,۳,۵,۷]. Additionally, ozone is safer than many other disinfectants because it decays to oxygen relatively quickly and leaves no harmful residuals. The efficiency for the oxygen → ozone conversion process (O۲ + O° →O۳) taking place during silent electric discharge (corona process) depends on several factors: oxygen source (O۲ or air); gas temperature and presence of impurities in the gaseous phase. The efficiency presented by most of the commercially available corona devices, using air as the O۲ source, is l۰.۴ – ۲.۰ wt% and requires an “apparent” energy demand (where costs concerning gas refrigeration and heat exchange are not considered) of l۱۴–۲۸ Wh/g. Considering that nitrogen is not an inert gas inside the corona device, this experimental approach using air presents the environmental inconvenience of releasing strong pollutants such as NOx compounds and HNO۳ into the atmosphere. Another commercially available technology for ozone generation is based on electrochemistry (water electrolysis: ۳H۲O→O۳ + ۶H+ + ۶e–) [۳] . This approach can be achieved by suitable choice of the anode material to have a high over potential for OER. In addition to, the material electrode in anode should have good conductance, high durability under drastic operating conditions, and particularly good electrocatalytic activity for ozone production. Different electrodes contain β-PbO۲, Pt, Pt composites, boron-doped diamond, TiO۲ thin films on Si/TiOx/Pt substrate, and Ti/Ni-Sb-SnO۲ catalysts are among the materials that have been used for EOP.[۱-۵] In this work, a high-performance porous titanium oxide electrode (Ti/TiO۲/Ni-Sb-SnO۲) has been developed for electrochemical production of ozone . The Ti/TiO۲ electrode was prepared using anodizing method at high voltage for forming a layer of porous TiO۲ on the surface of Ti mesh, then followed by depositing a layer of Ni-Sb-SnO۲ under deep eutectic solvent on the Ti/TiO۲ surface. The deep eutectic solvent was used for electrodepositing, because its great effect on electrode performance. Ozone was electro generated from tap water on Ti/TiO۲/ Ni-Sb-SnO۲ electrodes at different operating conditions. Higher efficiency of O۳ generation was obtained at ۳ V in tap water (Fig. ۱a).other electrode only with acidic electrolyte exponent to ozone generation but 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 water treatment . Figure۱b show the influence of COD removal as functions of the ozonation time.