Study On Modification Of Graphite Felt And Its Catalytic Degradation Of Organic Pollutants

Wet air oxidation is a typical advanced oxidation technology,which can use oxygen in the air（O₂）to oxidize pollutants under high temperature and pressure conditions.This technology has achieved satisfactory results in the conversion of toxic or refractory organic pollutants into intermediates with high oxidation states,and ultimately into carbon dioxide and water.However,its reaction is strongly dependent on high temperature and pressure,which can lead to excessive energy consumption and make operation difficult.Carbon materials have been widely concerned in the aspect of electrochemistry because of their good physical and chemical properties.Carbon materials can be used as catalysts for catalytic reactions,and can also be used as carrier supported catalysts for catalytic reactions.In this paper,electro-assisted wet air oxidation（ECWAO）system was established to explore the catalytic degradation of organic pollutants by anode materials through modification of carbon materials as anode materials and construction of electro-assisted wet air oxidation（ECWAO）system at room temperature and pressure.The main research work of this paper is as follows:The metal-free Nitrogen-doped graphite felt（N-GF）material was successfully prepared by hydrothermal method with different nitrogen sources.N-GF material was used as anode to catalyze the degradation of Rhodamine B in ECWAO system.The results showed that the degradation of rhodamine B was the best under+1.0V potential when GF was pretreated with 2%H₂O₂ and disodium ethylenediamine tetraacetic acid as nitrogen source.N-GF electrode showed stable catalytic degradation effect in a wide p H range of 3.0 to 6.7,and the catalytic degradation effect was slightly worse in p H range of6.7 to 11.0 than in neutral condition.LC-MS analysis of rhodamine B on N-GF showed that the degradation of rhodamine B on N-GF was firstly caused by the destruction of the color structure through N-deethylation,then through the process of deethylation,dehydroxyl,dealdehyde,ring-opening,and finally decomposed into small molecular acids.Expansive experiments showed that N-GF anode material could degrade six other pollutants,including methylene blue,sulfamethoxazole,basic fuchsin,triclosan and bisphenol A,in ECWAO reaction system.The Ni@NiO/GF composite anode material was prepared by impregnation method and pyrolysis method.The degradation of 10 pollutants represented by dyes,drugs and care products was studied in the ECWAO reaction system.Through the analysis of a series of degradation intermediates detected in the degradation process of various pollutants and the calculation of density functional theory,it is shown that the degradation path of pollutants in the ECWAO reaction system depends on the different chemical structures of various pollutants.After being treated by ECWAO reaction system,the toxicity of organic pollutants is greatly reduced and their biodegradability is significantly enhanced.The average specific energy consumption（SEC）of ECWAO reaction system for treating different pollutants is only 4.51-12.98 k Wh kg-TOC^-1,which is much lower than the SEC value of traditional electrooxidation system.Therefore,the ECWAO reaction system is expected to be applied to the pretreatment before biological treatment.