In Situ Preparation Of H₂O₂ By Air Electrode Electro Fenton Treatment Technology And Its Study Of Difficult To Degrade Organic Pollutants

The in situ preparation of H₂O₂ electro-Fenton technology is considered as one of the feasible technologies for the treatment of refractory organic pollutants.Among them,cathode materials and reactor devices are the research hotspots of electro-Fenton technology and the key to the maximum performance of the technology.This thesis focuses on the screening and modification of cathode materials,the optimisation of electrode preparation conditions and the construction of a new air electrode reactor.The relationship between electrode structure and electrode performance is explored,and the performance of the new air electrode reactor in producing H₂O₂ and degrading pollutants is evaluated.The best performance of VCX-72R carbon black（CB）material was selected among various carbon materials,and the results of the comparison study between nitric acid and sodium dodecylbenzene sulfonate surfactant modification of CB carbon materials showed that the nitric acid modified electrode had better performance,and the H₂O₂ yield was about 146 mg/L after 120 min of electrolysis.The structural characterisation of the carbon material showed that the pore structure and surface wettability of the carbon material had a greater influence on the electrode performance than the functional group structure;suitable pore structure distribution and pore surface area can provide more electrochemical active sites for oxygen adsorption and transfer;the surface hydrophobicity prevented the electrolyte from immersing into the electrode and causing structural damage.The surface hydrophobicity can prevent the electrolyte from penetrating into the electrode and causing structural damage,thus improving the performance of the electrode.The results can provide a reference for the preparation and screening of electrode materials.The electrode preparation conditions were optimised by varying the CB/PTFE mass ratio,calcination temperature and doping with other compounds（e.g.cerium dioxide,polyaniline and covalent organic framework）,and it was found that the best electrode performance was achieved with a CB/PTFE mass ratio of 5:4,calcination temperature of350°C and no doping with other compounds.A new air electrode reactor was constructed,in which the optimum electrolysis conditions for the single-cathode air electrode reactor were:p H=7,electrolyte concentration 0.075 mol/L Na₂SO₄,current density 10 m A/cm²,rotational speed 150r/min,plate spacing 4.5 cm,and its H₂O₂ yield was 180 mg/L,compared to the aeration reactor H₂O₂ yield of 121 mg/L.Compared with the aeration reactor H₂O₂ yield of 121mg/L,the H₂O₂ yield of the single cathode air electrode was increased by about 50%.The air electrode reactor cathode construction study also found that the H₂O₂ yield of single cathode air electrode reactors constructed with single-sided cathodes and double-sided cathodes was essentially the same,and when the number of single-sided cathodes was increased to two to four,the H₂O₂ yield of the air electrode reactor increased from 310mg/L to 518 mg/L,with a significant increase in H₂O₂ accumulation.The COD removal rate of phenol and trichlorophenol by the air electrode reactor with four single cathodes could reach 66.4%and 89.6%,which was a further improvement over the COD degradation rate of 57%for phenol by the single cathode air electrode;the COD removal rate for coal-to-oil wastewater was about 48%.