The presence of tetracycline (TC) has been detected in the human living environment, and its complex structure makes it difficult to degrade. The green and efficient utilization of electroactivated persulfate advanced oxidation technology for the degradation of tetracycline remains a challenge. In this study, N-doped reduced graphene oxide (N-rGO) was prepared using a hydrothermal treatment method with urea as the nitrogen source. Four different mass ratios of graphene oxide (GO) to urea were synthesized, and the optimal mass ratio was determined through degradation experiments of tetracycline. The N-rGO/EC/PMS three-dimensional electrocatalytic system was constructed, and the influence of the experimental data on TC degradation, such as initial pH, PMS dosage and voltage, was determined. Characterization analysis using scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and other methods was conducted. The efficient catalytic ability of N-rGO was demonstrated through the generation of hydrogen peroxide ( H2O2) and consumption of peroxymonosulfate (PMS). The superiority of the three-dimensional (3D) electrochemical advanced oxidation process was proposed by combining different systems. Furthermore, the presence of hydroxyl radicals (.OH), persulfate radicals ( SO4 ·−), and singlet oxygen (1O2) was identified using electron spin resonance (ESR) technology. The utilization of N-rGO as a three-dimensional electrode, coupled with the advantages of PMS activation and electrochemical oxidation processes, is a promising method for treating organic pollutants in wastewater.

Nitrogen-doped reduced graphene oxide (N-rGO) three-dimensional electrode electrochemically activates persulfate for the degradation of tetracycline
    Abstract
    1 Introduction
    2 Experimental
        2.1 Chemicals and materials
        2.2 Synthesis of nitrogen-doped graphene
        2.3 Procedure
        2.4 Analytical methods
    3 3. Results and discussion
        3.1 3.1. Characterization
            3.1.1 SEM analysis
            3.1.2 FT-IR analysis
            3.1.3 XPS analysis
            3.1.4 XRD analysis
        3.2 The removal of TC
        3.3 Comparison of different processes for TC removal
        3.4 Influence of operating parameters
            3.4.1 Mass ratio of urea to GO
            3.4.2 Applied voltage
            3.4.3 PMS dose
            3.4.4 Initial pH
        3.5 Performance of different oxidation systems
            3.5.1 Activate PMS capability
            3.5.2 Activate H2O2 capability
        3.6 Reaction mechanism discussion
            3.6.1 Identification of active species
            3.6.2 Mechanisms for degradation
    4 Conclusion
    Acknowledgements 
    References

• Xin Liu(State Key Laboratory of Separation Membranes and Membrane Processes, Tiangong University, Tianjin 300387, China, School of Environmental Science and Engineering, Tiangong University, Tianjin 300387, China)
• Yonggang Zhang(State Key Laboratory of Separation Membranes and Membrane Processes, Tiangong University, Tianjin 300387, China, School of Environmental Science and Engineering, Tiangong University, Tianjin 300387, China)