Study On Metal-Organic Framework Derived Materials In The Treatment Of Rhodamine B By Electro-Fenton System

Dye wastewater is seriously harming the global ecological environment,and due to the difficult degradability of organic dyes,the organic dyes often enter the human body with the biological chain,causing damage to the body organs such as kidney,brain,liver.However,the traditional water treatment technology is difficult to remove it completely,so there is an urgent need to develop an efficient water treatment technology.Electro-Fenton technology is one of the most effective water treatment technologies,which has received a lot of attention and development from researchers because of its advantages such as in-situ H₂O₂ generation and strong oxidation capacity.However,the electro-Fenton technology still faces problems of low cathodic H₂O₂ yield and narrow application p H range,which limit its practical application.In this thesis,two parts of experiments are designed to address the above problems of electro-Fenton technique.The first part of the experiment is the synthesize of MoO₃/ZIF-67 precursor by hydrothermal method with MoO₃ nanorods as the substrate,followed by high temperature calcination of MoO₃/ZIF-67 under argon atmosphere to prepare a new nanocomposite MoO_3-x/C/Co O,and the material was coated on carbon felt cathode for the study of the removal of organic dye rhodamine B by electro-Fenton system.The material was successfully synthesized as demonstrated by SEM,XPS and XRD characterization.In addition,XPS results showed that MoO_3-x/C/Co O has more oxygen defects compared with MoO₃,and the oxygen defects facilitate the adsorption and activation of oxygen by the cathode,increasing the reactive sites.In addition oxygen defects are more likely to excite electrons,thus improving the overall electrical conductivity and electrochemical properties of the material.The nitrogen adsorption experiments showed the presence of a large number of mesopores in MoO_3-x/C/Co O,and the BET specific surface area was calculated to be 85.8027 m²/g.The CV results showed that the MoO_3-x/C/Co O modified carbon felt(MoO_3-x/C/C/Co O@CF)electrode has a more positive O₂ initial reduction potential and a higher O₂ reduction peak current density compared with the conventional carbon felt（CF）electrode.The EIS results showed that the MoO_3-x/C/Co O@CF electrode has a higher electrical conductivity compared with the CF electrode,and the H₂O₂ generation experiments showed the highest H₂O₂ generation（124.6μmol in 1 h）when the MoO_3-x/C/Co O@CF electrode was used as the cathode.In the electro-Fenton experiment with MoO_3-x/C/Co O@CF electrode as the cathode,78.5%of the organic dye Rhodamine B in water could be removed in 1 h,which was much higher than the control group（37.5%）.In conclusion,MoO_3-x/C/Co O has excellent application prospects in electro-Fenton system.In the second part of the experiment,Fe-BTC was used as the precursor to obtain the MOF derivative Fe₃O₄/C through high-temperature calcination,and Fe₃O₄/C was used as a Fenton reagent in the electric Fenton system for the first time.XRD and SEM results proved that the material was successfully synthesized.Nitrogen adsorption experiments showed the presence of a large number of mesopores in the material,and the BET specific surface area of the material was calculated to be73.3310 m²/g.The magnetic test results proved that the material has a large magnetic property,which makes it easy to be recovered after the electro-Fenton experiments.The results of electro-Fenton experiments showed that even under neutral conditions,the system with Fe₃O₄/C（600°C）as catalyst could still achieve 55.5%removal of Rhodamine B,which was much higher than the conventional Fenton reagent（30.6%）.In addition,the removal rate of Rhodamine B could still reach 49.5%after three cycles of this material,indicating its good reuse capacity.In summary,Fe-BTC-derived Fe₃O₄/C material is a more ideal candidate for Fenton’s reagent.