Study On Preparation And Performance Of Anode Used In Directly Electrolyzing Seawater For Anti-pollution

In order to prepare an excellent metal oxide electrode used in directly electrolyzing seawater for anti-pollution, the effects of doping element, preparation technics and so on to the performance of metal oxide electrode are discussed. Electrode's invalidation mechanism is discussed. The Cl₂ evolution efficiency of RuIrSnTi/Ti electrode in electrolyzing seawater and the effect of MnO₂ to electrode's performance are also discussed.This paper discusses the electrochemistry performance of RuTi/Ti,RuIrTi/Ti,RuIrSnTi/Ti electrode. The results indicate: RuTi/Ti electrode has perfect catalyse performance to chlorine evolution, low chlorine evolution potential, high oxide evolution potential at 440℃with Ru: Ti=3:7 (mol ratio). But it has short intensifying life and low potential difference of Cl₂ and O₂ evolution potential. Under the condition of Ir dipped in Ru₄₀Ti₆₀/Ti electrode to substitute Ru, Ru₃₀Ir₁₀Ti₆₀/Ti electrode has the lowest chlorine evolution potential. The intensifying life of metal oxide electrodes is becoming long with Ir content increasing. And from the resulte of element analysis by SEM and electron probe, Ir segeregation in the surface of electrode is found. After Sn is dipped in Ru₃₀Ir₁₀Ti₆₀/Ti to substitute Ti, the intensifying life of electrode is becoming long, but Cl₂, O₂ evolution potential increase. The temperature of dying and thermal oxide can be confirmed by TGA and DTA.The effects of thermal temperature, solution concentration, coat structure and Ti-based's preparation are also discussed. The results are that: Different compositions have their own different thermal oxide temperature. Ru₁₅Ir₁₅Ti₇₀/Ti electrode has low Cl₂ evolution potential and long intensigfying life when the thermal oxide temperature is 440℃。Under the same brush time, the solution concentration has direct ratio with coat weight. Electrode's intensifying life increases with coat weight increases, but the intensifying life of unit coat weight is the longest when the solution concentration is 0.79 mol/L. IrO₂ middle-layer can increase DSA's intensifying-life. Electro-catalyze character mainly depends on the surface character and the inert structure affects the surface structure. Some hole is turned out on Ti-based surface in NaBr solution and this kind of Ti-based is used to prepare metal oxide electrode. It is found that: electrode's real surface area and unit area quantity of electrode coat all increase. The intensifying-life is becoming long. However, the chlorine evolution potential only has little increase. AC-impedance technique is used to analyze electro-performance of metal oxide electrode. The metal oxide electrode is made of Ti-based and metal oxide coat, so LR(QR)(QR) can be used to simulate AC-impedance chart. The result is that: Added Ir can reduce film resistant and reaction resistant. Film resistant is becoming high and reaction resistant low with the thermal oxide temperature increasing. After adding Sn, electrode's film and reaction resistant all increase.The current efficiency of RuIrSnTi/Ti electrode is measured in seawater. After adding Sn, Cl₂ evolution efficiency of electrode increases. Ru₃₀Ir₁₀Sn₅₀Ti₁₀/Ti electrode has high current efficiency. Current efficiency reduces with the seawater concentration falling. Mn²⁺ oxidation efficiency in anode has relation with current and solution temperature. Increasing solution temperature is propitious to Mn²⁺ oxidation. The performance for Cl₂ evolution greatly reduces after the electrode is coated with MnO₂.