The Law Of H₂O₂ Production By Water Oxidation In KHCO₃ Electrolyte And Its Environmental Application Enlightenment

Hydrogen peroxide（H₂O₂）is an important chemical,widely used in medical disinfection,industrial textile,chemical synthesis and other fields.At present,the anthraquinone method is the most commonly used method for synthesizing H₂O₂,but it has disadvantages such as complex reaction conditions,limited operational safety and environmental protection.Based on the background,electrochemical synthesis of H₂O₂has attracted the attention of researchers as a green and safe H₂O₂synthesis method.It is particularly noteworthy that a novel method for the electrochemical indirect oxidation of water to H₂O₂in an aqueous electrolyte containing HCO₃^-has attracted much attention from researchers at home and abroad in recent years.At present,most scholars in this direction mainly focus on the synthesis of H₂O₂anode materials by highly efficient electrochemical water oxidation,while the characteristics of the prepared H₂O₂products and their related potential applications are less explored.In this paper,according to the reaction principle of indirect electrochemical oxidation of water to synthesize H₂O₂in the electrolyte containing HCO₃^-,F-doped Sn O₂conductive glass（FTO）was selected as a typical anode to systematically study the objective law of electrochemical synthesis of H₂O₂in KHCO₃electrolyte.According to the characteristics of low purity and easy decomposition of THE prepared H₂O₂product,the related laws of degradation of methylene blue and tetracycline by electrochemical indirect oxidation of water to produce H₂O₂were explored.The main research contents and conclusions of this paper are as follows:（1）FTO has good stability in KHCO₃electrolyte.After 12 hours of constant voltage reaction,there is basically no electrolytic corrosion.It can be used as an anode for electrochemical indirect oxidation of water to produce H₂O₂.The comparative study of electrolytes confirmed that the electrochemical synthesis of H₂O₂in KHCO3 electrolyte was achieved indirectly.At first,HCO₃^-is oxidized to HCO₄^-（HCO₃^--2e^-+H₂O→HCO₄^-+2H⁺）,then HCO₄^-mediates water oxidation to produce H₂O₂（HCO₄^-+H₂O（?）H₂O₂+HCO₃^-）.The electrochemical analysis shows that the electrochemical synthesis of H₂O₂in KHCO₃electrolyte needs to be carried out at a higher voltage（E^θ>1.80 V vs.RHE）,and the electrochemical oxidation decomposition of H₂O₂product（H₂O₂→2H⁺+O₂↑+2e^-,E^θ=0.695 V vs.RHE）,resulting in that the amount of H₂O₂produced by electrochemical indirect oxidation water does not continue to increase with the reaction time,and the concentration and purity of the prepared H₂O₂product are limited.In addition,the placement tracking test of H₂O₂product found that the prepared H₂O₂product could not be stably preserved in KHCO₃electrolyte,and there was a self-decomposition phenomenon that could not be ignored.（2）Based on the basic characteristics of electrochemical synthesis of H₂O₂in KHCO₃electrolyte,the degradation of methylene blue and tetracycline by using the prepared H₂O₂ware studied.It was found that the electrochemical generation of H₂O₂in KHCO₃electrolyte could degrade methylene blue.The comparative test found that the electrochemically generated H₂O₂in the KHCO₃electrolyte could achieve the degradation of methylene blue.Under the constant pressure condition of 2.8 V vs.RHE,20 ppm methylene blue solution in water could degrade 90%in about 140 min.Free radical capture experiments confirmed that the electrochemical synthesis of H₂O₂could be activated to·OH by HCO₃^-,which drove the degradation reaction of methylene blue in water.In addition,H₂O₂products stored in KHCO₃electrolyte can be directly used for tetracycline degradation in water.After the reaction,the KHCO₃electrolyte was mixed with tetracycline solution,and the 10 ppm tetracycline of in water could be degraded by more than 90%in 90 min.In this paper,the discovery of the law of H₂O₂production by water oxidation in KHCO₃electrolyte,and the research work on the degradation of methylene blue and tetracycline based on this discovery can provide an experimental theoretical basis for the objective understanding of the phenomenon of electrochemical synthesis of H₂O₂in HCO₃^--containing electrolyte.At the same time,it provides direction inspiration for its subsequent applications.