Study On Electrosynthesis Of Ferrate With Gas Diffusion Electrode

Ferrate,as a new type of water treatment agent,exhibits excellent synergistic functions of removing pollutants of oxidation,adsorption,and flocculation.It has a very good application prospect in sewage treatment.In order to reduce the problem of high energy consumption existing in the preparation of ferrate by electrochemical methods,this thesis proposes a method and device for electrosynthesis of ferrate with gas diffusion electrodes with low energy consumption and simple process.Ferrate was successfully prepared using self-made gas diffusion electrode.The effects of current density,electrolyte concentration,temperature,and electrolysis time on the electrosynthesis of ferrate by gas diffusion electrodes was explored systematically.The effect of Fe3O4 incorporation on the electrosynthesis of ferrate by Fe-Fe3O4 composite anode was explored.The results of this research are as follows:(1)A gas diffusion electrode was prepared.The electrode potential of the oxygen reduction reaction in the alkaline solution is-0.054 V(vs.Hg/HgO),which is far lower than the electrode potential of the traditional nickel sheet,It can meet the requirements of electrosynthesis of ferrate.(2)A method of electrosynthesis of ferrate with gas diffusion electrode was proposed,and ferrate was successfully prepared.By optimizing the three process parameters of current density,electrolyte concentration and temperature,the best process conditions for electrosynthesis of ferrate were determined:the current density was 7.5 mA/cm2,the sodium hydroxide solution concentration was 16 mol-L-1 and the temperature was 40?(3)Under the best process conditions,the current efficiency of electrosynthesis of ferrate by gas diffusion electrode is 28.54%,the cell voltage is 0.756 V,and the energy consumption is 2.57(kW-h/Kg)Compared with the traditional electrolysis method,the cell voltage significantly reduced,the current efficiency improved,and the power consumption was reduced by 72.60%.The electrosynthesis of ferrate with gas diffusion electrodes has a very significant energy-saving effect,and thus has industrial application prospects.(4)Electrochemical analysis shows that the ferrate undergoes a complex intermediate reaction process during the generation process,in which a passive Fe2O3 film is produced.Therefore,it is possible to further improve the current efficiency of electrosynthesis of ferrate through the improvement of the anode.(5)The Fe-Fe3O4 composite anode with high density and low resistance was prepared by mixing,tableting,sintering the mixture of iron and ferric oxide under argon atmosphere.Parameter optimization shows that the composite anode doped with 10%Fe3O4 has the best electrosynthesis ferrate.The current efficiency was higher than pure iron at a current density of 7.5-15 mA/cm2,and the power consumption was less than pure iron.With the addition of more Fe3O4,the Fe-Fe3O4 composite anode overcome the problem that the surface of the pure iron plate is more easily passivated at a higher current density to some extent,The Fe-Fe3O4 is more suitable for the electrosynthesis of ferrate at a high current density...