Investigation Of Preparation And Application Of Ti/RuO₂-IrO₂-SnO₂-Sb₂O₅ Electrodes

Disinfection is an important process in drinking water and sewage treatment. Currently, hypochlorite is one of the most widely used disinfectants, which is usually generated by electrolyzing concentrated NaCl solutions using dimensional stable anodes (DSAs). In order to save the chemical cost, seawater has been used as electrolyte to replace the concentrated chlorine solutions in recent years. However, this bring about two problems, namely the low stability of the classical DSAs and the low yields for CI2 evolution, because the chloride concentration of the seawater is much lower than that of the concentrated NaCl solutions used in chlor-alkali industry. In this paper, a new type of DSA, Ti/RuO2-IrO2-SnO2-Sb2O5, was investigated for Cl2 evolution from seawater. The study included three parts:the optimization of anodes preparation parameters, the characterization of anodes performance, and the exploration of the influence of operation parameters on seawater electrolysis.It was shown that the Ti/RuO2-IrO2-SnO2-Sb2O5 anodes could work stably at high current density for Cl2 evolution from the seawater. The molar ratio of components and calcination temperature could highly influence the efficacy of the anodes. The anodes preparation parameters were optimized:the molar ratio of Sb:Ir:Ru:Sn was 10:10:20:60, the calcination temperature was 500℃. The characterization of anodes performance showed that the coating was compact, with few cracks detected. The various components in the coating were highly intermixed, that is the coating existed as a solid solution. The anodes demonstrated good activity and high stability for Cl2 evolution. The service life was about 658 hour under the conditions of the accelerated life test and it was predicted to be over 5 years at a current density of 1500 A m-in seawater. The best operation parameters on seawater electrolysis were:a current density of 1500 A m"2 and a temperature range of 15℃-25℃. The current efficiency was 71.1%-86.7%, depending on the operational conditions.