Preparation Of GA-Based Cathode And Its Study On Degradation Of Organic Wastewater

The electro-Fenton oxidation is an advanced oxidation technology that has emerged in recent years.However,the catalytic performance of the traditional electro-Fenton cathode material is limited,the regeneration of Fe?II?is difficult and the pH range is narrow.Therefore,the cathode material has attracted wide attention.Due to the graphene aerogels owing low density,high porosity rate,high specific surface area,good mechanical properties and different conductivity characteristics.In this paper,graphene aerogel?GA?was prepared by reduction self-assembly method and freeze-drying method.The GA was used as a carrier to carry out doping with Fe,Cu and Fe/Cu,respectively.Fe-doped graphene aerogel?Fe-GA?,Cu-doped graphene aerogel?Cu-GA?and Fe/Cu co-doped graphene aerogel?Fe/Cu-GA?wereprepared by hydrothermal reduction method and natural drying method.The microstructure and mechanical properties of GA and modified GA were characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,Raman spectroscopy,X-ray photoelectron spectroscopy?XPS?,et al.The results show that GA and metal doping GA have an excellent catalytic performance.The prepared GA,Fe-GA,Cu-GA and Fe/Cu-GA as the electro-Fenton cathode,respectively,using the GA has the electro-adsorption properties,and the synergy between metals to obtain high catalytic activity of electricity cathode materials,and the ultimate goal was to improve modified GA electrode on the application of pH value in the traditional electro-Fenton,expand the H₂O₂ yield and reform the mineralization ability.The results showed that 1)when the GA was used as a cathode material for electro-Fenton treatment of rhodamine B,the degradation rate reached 98%when the pH was 3,the current density was 30 mA/cm²and the concentration of Fe²⁺was 15 mmol/L,the COD removal rate reached 79%.Under the same conditions,the degradation rate of ciprofloxacin reached 90%,and the COD removal rate reached 73%.During the continuous degradation of Rhodamine B by electro-Fenton,the degradation rate decreased only from 98%to 93%after 6 times degradation,indicating the excellent stability of GA cathode.2)When Rhodamine B was treated with modified Fe-GA as electro-Fenton cathode material,the degradation rate could reach 99%at pH=3,and the degradation rate reached 96%at pH=8.During the continuous degradation of electro-Fenton,the degradation rate decreased from 99%to 91%after degradation for 8 times.3)When the modified Cu-GA was treated as the cathode material of electro-Fenton process,the degradation rate of Rhodamine B reached 97%at the optimum pH=3,and the degradation rate reached93%at pH=8.After 8 successive degradation,the degradation rate dropped from 97%to 85%.By changing the doping metal to copper,the problem of producing iron sludge in the electro-Fenton system can be improved effectively.4)The modified Fe/Cu-GA has an excellent oxidation efficiency to Rhodamine B in the pH range of 3-8,and its degradation rate up to more than 99%at the optimum pH value of 3.The strong oxidation efficiency due to the strengthening of Cu?II?in electro-Fenton system.Due to the doped Cu?II?and Fe?II?reacted with the H₂O₂ produced by the cathodic reaction in situ,and Cu?II?/Cu?I?and Fe?III?/Fe?II?had a synergistic effect in Fenton process.Compared with Fe-GA and Cu-GA,not only the Cu?II?/Cu?I?reacted with H₂O₂ produced·OH.but also promoted the cycling of Fe?III?/Fe?II?.In the Fenton system,the Fe?II?cycle accelerated,and the release rate of·OH was increased,so that the rate of oxidation degradation of organic matter was relatively high.