Performance Of Boron-doped Graphene Aerogel Modified Gas Diffusion Electrode For In-stiu Metal-free Electrochemical Advanced Oxidation Of Bisphenol A

With the continuous improvement of industrial technology in modern society,water pollution has become the focus of global attention.In the production activities,a large number of organic pollutants are discharged into the water,causing great harm to the water environment.In particular,some difficult to degrade pollutants present long-term accumulation in the water environment,resulting in a serious threat to human health.In recent years,scholars at home and abroad have carried out lots of research on wastewater treatment technology.The traditional physical and chemical methods possess low efficiency in the treatment of organic wastewater.In contrast,electrocatalysis technology has been widely concerned because of its advantages of simple operation,high efficiency and environmental friendliness.In-depth study shows that electrode materials play a key role in the electrocatalytic process,which determines the pollutants removal efficiency.Therefore,the preparation of electrode materials with high catalytic performance is the key to study the removal of refractory organic pollutants in wastewater.In this paper,bisphenol A(BPA),a refractory endocrine disruptor,was selected as the research object to explore the application of high-efficiency metal-free electrode in the advanced electrochemical oxidation process(EAOPs).Firstly,the novel boron-doped graphene aerogel(BGA)modified gas diffusion electrode(GDEs)was synthesized and employed for bisphenol A(BPA)degradation in nonmetallic EAOPs.The physical and chemical performances of BGA were characterized by adsorption experiments and the characterization techniques,such as SEM,XRD,XPS,Raman and BET.The electrocatalytic activities on catalyst-free electrode,graphene aerogel modified gas diffusion electrode(GA-GDEs)and BGA-GDEs in EAOPs were investigated.The result displayed that BPA was almost completely degraded within 60 min on BGA-GDEs,while the removal efficiency with GA-GDEs and catalyst-free electrode were 88.92%and 61.35%,respectively.It can be proved that boron doping could improve the catalytic performance of the electrode.The effect of the BGA doping contents and pH on BPA degradation was evaluated in the metal-free EAOPs process,and compared with the traditional EF system.It was found that 2.4%of BGA mass was beneficial to obtain an optimal degradation efficiency.The metal-free EAOPs on BGA-GDEs manifested smaller change in reaction rate(0.0952 min-1)compared with that of traditional Electro-Fenton process(0.19115 min-1)when the initial pH increased from 3.0 to 9.0,revealing that the catalytic activity of this metal-free system exhibited excellent stability over a wide pH range.After the fifth reuse,the degradation efficiency of BP A still attained about 90%,and TOC removal can reach 89.68%,which proved that BGA-GDEs possessed excellent stability.The main BPA degradation process in metal-free EAOPs is:The O2 produced H2O2 by 2e-ORR,which was attributed to the enhancement of H2O2 in-situ decomposition to ·OH to degrade BPA.The intermediate products of degradation were identified by LC-MS.Eventually,the in-situ metal-free electrocatalysis on BGA-GDEs could be considered as an environment-friendly pollutant removal technique without risk of metal contamination.