Preparation Of Hydrophobic P-BN@β-PbO₂ Composite Electrode And Its Electrocatalytic Degradation Of Antibiotics

Electrocatalytic oxidation is considered as one of the most promising advanced oxidation technologies in the field of antibiotic wastewater treatment because of its advantages of simple operation,high degradation efficiency,wide application and environmental friendliness.Anode material plays an important role in electrocatalytic oxidation process.Anode material directly determines the oxidation process,the final oxidation product and the removal rate of target antibiotics.β-PbO₂has become a hot topic in the research of electrocatalytic materials because of its low resistivity,high hardness and high oxygen evolution potential.In this study,a new type ofβ-PbO₂ anode without matrix was prepared by high pressure plastic plate method,and its degradation effect on doxymycin hydrochloride and cefazolin sodium was investigated.The degradation mechanism of p-BN@β-PbO₂ anode on two antibiotics was explored,so as to provide theoretical guidance for the development of electrode materials in new electrocatalytic oxidation method.The main research results are as follows:1.A novelβ-PbO₂ anode without substrate was prepared by high pressure plastic plate method.The 10%（p-BN/C）@β-PbO₂ electrode with the best electrocatalytic activity was selected by electrochemical workstation characterization.Combined with the SEM and XRD test results of p-BN@β-PbO₂ electrode,the agglomeration of the electrode surface will lead to the formation of the gap,which is conducive to the exchange of electrolyte solutes.The contact Angle test shows that the addition of hydrophobic outer layer improves the hydrophobic performance of the electrode,increases the lifetime of the electrode and reduces the occurrence of side reactions.2.10%（p-BN/C）@β-PbO₂ was used for linear sweep voltammetry test of anode material.The test results show that 10%（p-BN/C）@β-PbO₂electrode modified by PTFE hydrophobic outer layer has higher oxygen evolution potential,and the possibility of side reaction is greatly reduced,and the reaction efficiency is improved.The electrochemical reaction rate and current efficiency of 10%（p-BN/C）@β-PbO₂electrode are the most outstanding.CV results showed that there was no direct electron transfer between the target antibiotic and the electrode,and the reaction process was indirect oxidation.It was found that the CV curve integral area of no.（2）electrode was the largest and the voltammetry charge was the most prominent(q*=4.19×10^-2),indicating that it had higher electrochemical active area and electrocatalytic activity.3.The results of 8 cycles show that the prepared 10%（p-BN/C）@β-PbO₂ electrode has the ability of long-term stable operation.In one degradation experiment cycle（120 min）,the concentration of lead ion leached from the system was 279.18 ug/L.The effects of main experimental parameters on the degradation effect and kinetics of doxycycline hydrochloride and cefazolin sodium were investigated.The removal rate of 30 mg/L doxycycline hydrochloride was 92.69%and the removal rate of cefazolin sodium was 82.47%under the optimal degradation conditions of 120 min.4.The active species,complex products and intermediate products in the degradation of doxymycin hydrochloride and cefazolin sodium were analyzed by UV spectrophotometry and High performance liquid chromatography tandem mass spectrometer.It was found that indirect oxidation of 10%（p-BN/C）@β-PbO₂played a key role in the degradation of the two antibiotics.Explain the process of doxycycline hydrochloride（346 nm）and cefazolin sodium（272 nm）at the maximum absorption wavelength corresponding absorbance was gradually reduced to close to zero and with redshift,maximum absorption peak to long wave direction,ultraviolet region of the baseline,that target antibiotics to take off the group reaction in the process of degradation,the conjugate structure destroyed by quickly,And may be broken down into smaller molecular pieces.Finally,the intermediates of degradation of two antibiotics in the reaction system were speculated according to the literatures.5.The optimal reaction conditions are roughly the same,but the degradation rates of the two antibiotics are quite different.The degradation rates of doxycycline hydrochloride and cefazolin sodium were 96.29%and82.47%,respectively.Therefore,it is inferred that the active substance produced by the electrode system has high selectivity to the structure of tetrabenzene and the-NH₂ branch chain,but low reactivity to the C-S bond in the six-membered ring and N-C bond in the four-membered ring.