H₂O₂ Electro-synthesis And Pre-treatment Of Refractory Wastewater By Electro-Fenton

Electro-Fenton?EF? oxidation technology as environmentally friendly water treatment technology has been widely attention,its core technology is the electro-synthesis of H₂O₂by oxygen reduction reaction?ORR?.However,currently there is a problem of low hydrogen peroxide yield,it is extremely important to develop a catalyst with high hydrogen peroxide yield.The catalyst is used in the pretreatment of bio-refractory wastewater by EF to improve the biodegradability of wastewater,which provides a reliable theoretical basis for the industrial application of low-energy electro-Fenton pretreatment of refractory wastewater.This paper carried out the following work:?1?Six carbon-based catalysts were prepared by a series of modifications of CNTs,and their electrochemical characterization were recorded.The CV curves shows that each catalyst has an obvious oxygen reduction peak,indicating that these catalysts are active for ORR.RRDE test results showed that the ring current of O-CNTs was the largest and H₂O₂selectivity was the highest,with good 2e oxygen reduction performance.The FTIR and Raman spectroscopy of O-CNTs and CNTs were recorded,analysis showed that some hydrophilic groups were introduced to the surface of O-CNTs,which increased the defect density of carbon materials and provided more active site for the ORR,so O-CNTs has high H₂O₂selectivity.?2?In order to reduce the mass transfer diffusion limitations of oxygen,gas diffusion electrodes?GDE?was prepared to electrogeneration H₂O₂.The process parameters were optimized,the results showed that the ratio of CB to PTFE in the diffusion layer was 1:5,the ratio of O-CNTs to PTFE in the catalytic layer was 2:1,the constant current density was 14 m A/cm²,the electrolyte p H was 3,and the gas flow rate was 0.6 L/min.After the electrolysis for 120 min,the cumulative concentration of H₂O₂reached 610 mg/L,and the current efficiency was 77%.The difference of current efficiency of two kinds of H₂O₂electro-synthesis was explored,and results showed that CE_GDEwas almost greater than CE_RRDE,indicating that sufficient oxygen supply played an important role in electro-synthesis H₂O₂.The difference between the performance of pure CNTs and O-CNTs as the GDE catalytic layer for H₂O₂electro-synthesis were investigated,the results showed that the performance of O-CNTs-GDE was better than CNTs-GDE.?3?Using EF technology to treat RhB simulated wastewater,to explore the effects of different operating conditions on the Rh B removal rate,COD removal rate and energy consumption.The results showed that the[Fe²⁺]was 14 m A/cm²,the initial concentration of Rh B was 200 mg/L,and the above optimized conditions for degradation 60 min,the removal rate of Rh B and COD were 99%and 88%,respectively,and the energy consumption was 9 k Wh/kg _COD.Three kinds of refractory wastewater were pretreated by electro-Fenton technology for 15 min,their biodegradability was evaluated results showed that the biodegradability of the three kinds of wastewater was improved,which confirmed the universal applicability of short-term electro-Fenton treatment to improve biodegradability.The recyclability of GDE was evaluated,and the result showed that the energy consumption increased slightly after 7 cycles,indicating that GDE had good stability.