Study On Frequently Polarity Inverted And Long Lifetime DSA Electrode

DSA electrodes are widely used in chlor-alkali industry,water treatment,electroplating,electroorganic synthesis and other industrial fields.When the electrolyte contains a large amount of Ca²⁺and Mg²⁺,insoluble Mg（OH）₂/Ca₂CO₃ solids will be formed during the electrolysis process,which is called cathode scaling.Cathode scaling can reduce the conductivity and current efficiency of electrodes,and increase electrolytic energy consumption.In order to prevent the cathode from scaling,it is necessary to conduct regular descaling treatment on the cathode.In the electrolysis industry,mechanical descaling methods,scale inhibitor methods,and inverted electrode descaling methods are commonly used to dissolve or remove the scale layer on the cathode.The inverted electrode descaling method has the following advantages:low cost,good effect,easy operation,almost no need to suspend electrolysis during cleaning,and can avoid corrosion.It does not require additional cathode scraper plates,reducing the difficulty of equipment installation.However,DSA electrodes are usually used as anodes,and the active substances on the electrode surface will be reduced when the inverted electrode becomes a cathode,resulting in rapid electrode failure.In order to solve the above problems,this paper developed a DSA electrode with high stability,low cost,and high Faraday efficiency,which can be used for reverse electrode descaling in chlorine evolution systems.The main research work is as follows:（1）Used for the preparation,activity,and stability study of frequently inverted DSA electrodes:A RuO₂ electrode with a platinum intermediate layer（Ti/Pt/RuO₂）was prepared on the surface of titanium substrate by electroplating thermal decomposition method.The research shows that compared with Ti/RuO₂-Ti O₂,Ti/Ta₂O₅/RuO₂,Ti/Sn O₂-Sb₂O₅/RuO₂ and other chlorine evolution electrodes,the electrochemical active area,Faraday efficiency,and reverse electrode strengthening lifetime of Ti/Pt/RuO₂electrodes have significantly improved.Because the platinum plating method can form a tight intermediate layer,effectively protecting the titanium substrate from electrolyte erosion,forming an electrode intermediate layer with good conductivity,corrosion resistance,and large specific surface area.Pt has positive and negative electrolysis performance,which can effectively protect the titanium substrate from electrolyte corrosion under frequent reverse polarity conditions.（2）Optimization of Ti/Pt/RuO₂ electrodesBy changing the process conditions such as platinum loading and thermal decomposition temperature,the electrode composition and preparation process with higher stability and activity were optimized.（3）Application of Ti/Pt/RuO₂ electrodes.The most suitable application conditions for Ti/Pt/RuO₂ electrodes were studied for different inverting frequencies,stirring rates,temperatures,current densities,and salt water concentrations.The results show that the Faraday efficiency is 84.55～92.89%under the conditions of current density 750 A/m²,electrolysis temperature 25℃,and brine concentration 25 g/L;Under the condition of current density of 40000 A/m² and inversion frequency of 12 times/h,the inversion strengthening life can reach 74 hours,which is 70 times that of commonly used Ti/RuO₂-Ti O₂ electrodes.At a current density of 1000 A/m²,it is expected to work for 4 years.