Electrode Materials Development And Electrochemical Process For Advanced Treatment Of Livestock Wastewater

In recent years,China's livestock industry has developed rapidly and the treatment of livestock wastewater is imminent.The traditional biological treatment process is effective in high-concentration livestock wastewater but ineffective in low-concentration livestock wastewater treatment.The electrochemical cathode electro-Fenton and anode oxidation technology,as a new type of pollution-free advanced oxidation technology,has shown good performance in terms of advanced treatment of wastewater and biodegradability improvement.The wastewater treatment efficiency of electrochemical process is depended on the selection of electrode materials and the preparation of the electrodes.Therefore,to develop new electrode materials and preparation methods with good performance is a hot spot in this field.In this paper,the effect and mechanism of carbon nanotube loaded CeO₂ and added pore former NH₄HCO₃ on wastewater treatment were studied and the effect and mechanism of 2-ethylanthraquinone?EAQ?-modified graphite felt cathode coupled with PbO₂ anode oxidation on wastewater treatment were studied,the main conclusions are as follows:The carbon nanotubes were loaded with CeO₂,and the electrode holes were made with NH₄HCO₃.Transmission electron microscopy?TEM?and scanning electron microscopy?SEM?showed that a large amount of CeO₂ nanoparticles were attached to the surface of the modified carbon nanotubes,and the electrode pores were obvious.X-ray diffraction image?XRD?analysis confirmed that the material supported on the surface of the carbon nanotube was CeO₂.X-ray photoelectron spectroscopy?XPS?results analysis showed that the doping of CeO₂ shifted the binding energy of carbon nanotubes in the negative direction.Linear sweep voltammetry?LSV?analysis showed that the modified carbon nanotubes had stronger catalytic oxygen reduction activity.Cathode H₂O₂ accumulation experiments showed that when the ratio of carbon nanotubes,CeO₂ and NH₄HCO₃ is 6:1:1,the performance of the electrode is best and when the cathode potential is-0.75 V?relative to the saturated calomel electrode?,the pH of the electrolyte is 3,the cathode O₂ is saturated,the system has the best performance of accumulating H₂O₂,that is,the accumulated content of H₂O₂ is 180.1mg/L after 80 min electrolysis.The wastewater treatment experiments showed that when the concentration of cathode Fe²⁺was 0.3 mM,the effect of cathode Fenton treatment of wastewater was best.The removal rate of COD_Cr was 71.5%after 80 min electrolysis,and the BOD₅/COD_Cr of wastewater increased from 0.08 to 0.45.Ultra Performance Liquid Chromatography Coupled with Q-Exactive Orbitrap Mass Spectrometry?LC-MS/MS?analyzed the substances in the wastewater under different electrolysis times and the results indicated that some biodegradable refractory chemicals such as oxytetracycline,aminopyrine,oxadiazolyl and 3-methyl-2-quinoxalinecarboxylic acid can be removed by electro-Fenton,especially oxytetracycline within 20 min,the degradation rate was 100%.The?EAQ?-modified graphite felt electro-Fenton oxidation coupled with PbO₂ anode oxidation system was used in the advanced treatment of livestock wastewater.The SEM results showed that the surface of?EAQ?-modified graphite felt was rougher,and the surface of the prepared PbO₂ electrode was mainly pyramid-shaped?-PbO₂ crystal.XRD analysis showed that the surface size of the prepared PbO₂ anode was smaller.XPS analysis showed that the content of oxygen-containing functional groups on the surface of the?EAQ?-modified graphite felt increased.Hydrophilic performance test results showed that the hydrophilic properties of the graphite felt after modification increased.The results of LSV analysis showed that the?EAQ?-modified graphite felt has lower oxygen reduction potential and stronger catalytic oxygen reduction performance.The prepared PbO₂ anode has higher oxygen evolution potential and better catalytic oxidation of organic matter.When the electrolytic cell voltage was 2.8 V,Fe²⁺concentration was 0.3mM,and cathode O₂ was saturated,the system had the best effect on wastewater treatment,that was,the removal rate of COD_Cr was 71.5%after 90 min of electrolysis,and the BOD₅/COD_Cr of wastewater increased from 0.084 to 0.42.The.OH produced in the system was successfully captured by the electron paramagnetic resonance spectrometer?EPR?.