Study On The Electrochemical Degradation Of PFOA Wastewater By Home-made Gas Diffusion Electrodes Of LaNi_xY_1-xO₃

With the deepening of researches, people have come to realize some characteristics of perfluorinated compounds, such as refractory, environmental persistence and bioaccumulation in recent years. Perfluorooctanoate (PFOA) is the typical representative of perfluorinated compounds, which has reproductive toxicity, developmental toxicity and toxic mutagenic toxicity, and PFOA, as Persistent Organic Pollutants (POPs), is currently the most difficult to degrade. The present relevant research processes about PFOA were still in the development stage, this paper is in use of electrochemical methods, combined with advanced oxidation degradation,and the purpose of this paper is providing an idea of efficient degradation of PFOA wastewater in the future.In the paper, at the terms of preparation of gas diffusion electrodes, the perovskite catalyst LaNixY1-xO3(Y=Fe, Cu, Co, Sr) electrodes, doping different metal elements, carried on experiments about parameter optimization by analyzing the characterization; At the terms of application of gas diffusion electrodes of perovskite catalyst, experiments by self-made electrode as ca thode, ordinary graphite electrode as an anode, carried on degrading perfluorooctanoic acid wastewater. It was exploring the optimal degradation conditions in the use of single factor experiments, in addition, discussing the degradation mechanisms and degradation pathways.LaNiO3 have been widely used in the field of metal catalysts in the field of perovskite, catalyst B site is doping for preparation of different metal ions perovskite LaNixY1-xO3 by employing sol-gel method, additionally, employing a variety of characterization methods such as Cyclic Voltammetry (CV), methylene blue characterization, Transmission Electron Microscope (TEM), Scanning Electron Microscopy (SEM), thermogravimetry analysis, X-ray diffraction (XRD) analyse the corresponding performance of different gas diffusion electrodes, The experimental results showed it was at the condition of La:Sr:Co=1:0.8:0.2 that electrochemical properties greatly enhanced,750℃ calcination. The best ratio of graphite, PTFE, calcination temperature and calcination times of electrodes had been analyzed with orthogonal method. The experimental results also told it was at the condition of graphite 5.4g, PTFE 3.0g, calcination temperature 330℃ and calcination time 120 min that gas diffusion electrodes showed wonderful electrochemical performance.PFOA wastewater was degraded with LaNi0.8Y0.2O3 gas diffusion electrode.the best degradation conditions were discussed in this paper. It will achieve the best efficiency of degradation when the current density was 20 mA/cm2, pH 5,100 mg/L of the initial concentration, and 150 min of degradation time. The current density and PFOA of the initial concentration meet the first order reaction kinetics equation in the degradation process. The degradation products were analyzed by High Performance Liquid-Mass Spectrometer (HPLC-MS) in order to launch the possible degradation pathways. The results show that PFOA could be reacted in the joint action of HO· and O2, removing CF2 group one by one step, degrading into F- and CO2 ultimately.The research objective of this paper is intended to explore the most cost-effective parameters of PFOA wastewater degradation in electrochemical oxidation areas, providing an idea for effective degradation of perfluorinated compounds enrich the research and development process of perfluorooctanoic acid.