The Strengthening Method Research Of Electro-fenton Technology To Enhance The Degradation Performance Of Phthalic Acid And Azo Dyes

A large number of refractory chemicals and dye enter into the water with the development of industry,and some of the organic pollutants can damage the ecological system and threaten the human health,so the new method of more green and efficient should be developed to eliminate the chemicals pollution problem.Recently,E-Fenton process has become a research focus in the field of refractory organic wastewater treatment.There are two key factors as follows:?1?E-Fenton can generate H₂O₂ in situ to eliminate the risk of H₂O₂ in the transportation and storage.?2?It can realize the efficient recycle of Fe²⁺/Fe³⁺to reduce iron sludge quantity and secondary pollution.However,cathode materials should not only consider the rate of diffusion and mass transfer on their surface,but also concerns their electrochemical properties,because of the limit of dissolved oxygen in water phase.In addition,the restrictive traditional electrode apparent area leads to the weaker interaction between electrode and solution and lower electrolytic efficiency.Hence,reinforcing E-Fenton reaction interface to improve the current efficiency of H₂O₂ and the degradation rate of refractory organic,is a significant research subject of the basic theory.The detailed research work of this paper are listed as follows:1.Rapidly enhanced electro-Fenton efficiency by in situ electrochemistry-activated graphite cathodeFor the development of a highly active and energy-effective electro-Fenton process,a simple and efficient electrochemical method was used to modify the nitrogen-doped graphite in situ.Scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?and contact angle results showed that through ammonium nitrate electroactivation,this process could provide?I?a higher surface area,?II?more hydrophilicity,?III?much higher electrocatalytic activity toward the oxygen reduction reaction,and?IV?more nitrogen-containing functional groups.In this study,the H₂O₂accumulation concentration reaches the optimized value at-0.6 V vs SCE at the applied cathode potential.The reduction of oxygen to generate H₂O₂ was promoted,and the current efficiency of the electro-Fenton process was also upgraded from 57.96%to83.76%over 15 min.The apparent rate constant for the dye Brilliant Red X3B by electrochemisty is 0.178 min^-1,much higher than that of the Raw(0.073 min^-1).The dimethyl phthalate?DMP?and the diethyl phthalate?DEP?had the same results.Hydroxyl?·OH?radicals were identified as the main reactive oxygen species,which clearly increased after electroactivation.Moreover,the comparison with other commonly used solutions confirms the effectiveness of ammonium nitrate electroactivation for the electro-Fenton cathode.2.The solid superacid CeO₂-ZrO₂/SO₄^2-concerted catalysis with enhanced E-Fenton activity for oxidation degradation.We used CeO₂-ZrO₂/SO₄^2-as the catalyst to research the effect of catalysts-oxygen interface on E-Fenton in this chapter.The effects of different ratios of cerium and zirconium on the catalytic effect were studied.Scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?,Zeta potential and H₂O₂ detection testing results showed that the surface charge of composite catalyst became negatively charged in Na₂SO₄ electrolytes at pH 3.0,which was advantageous to the electrocatalysis producing H₂O_2.The best degradation of refractory organic condition was cerium:zirconia=1:2 for E-Fenton.Raman,EPR and NH₃-TPD results showed that the introduction of zirconium is conducive to the production of oxygen vacancies and the acid sites of solid superacid.Therefore,solid super acid CeO₂-ZrO₂/SO₄^2-can strengthen the interface between oxygen and catalyst under the action of electric field and improve the efficiency of electro-Fenton degradation.3.The effect of CeO₂/SO₄^2-synthesis method and morphology on the oxidation of catalytic Fenton oxidation.In this chapter,two different morphologies of CeO₂ were successfully prepared by hydrothermal method and microwave method.And we modified CeO₂ by hydrothermal with a surfactant.The effects of different preparation methods such as morphology,BET and Raman were investigated on the catalytic performance.The efficiency of degradation of refractory organic matter was also compared.The apparent rate constant for the dye Brilliant Red X3B by hydrothermal with a surfactant is 0.130 min^-1,much higher than that of the Raw(0.102 min^-1).The catalyst has good stability.After 6 cycles,the removal rate of X3B is also 92.13%.