Synthesis of Fe/Mn Co-doped g-C 3 N 4 heterostructures for synergistic persulfate activation: green, low cost preparation process and the catalytic performance

As global environmental issues grow increasingly severe, ROPs have become a critical challenge in water pollution control. Persulfate-based advanced oxidation processes have garnered wide attention, and g-C3N4-based composites have emerged as a research hotspot in recent years. This study fabricated Fe/Mn co-doped g-C3N4 heterostructures (MnFe2O4/g-C3N4) using ultrasonic-assisted calcination, significantly improving catalytic performance. The results showed the ultrasonic-assisted sample (GCDCS-5) achieved a higher MB degradation efficiency (95.4%) than others. After optimizing the manganese source (MnCl2), calcination temperature (600°C), and precursor ratio (1:50), the MB degradation rate rose to 99.2%. Characterization revealed that MnFe2O4 nanoparticles were uniformly dispersed in g-C3N4 layers, forming a stable heterostructure, and the Fe2+/Mn3+ redox cycle accelerated electron transfer. Additionally, the material retained 85% degradation efficiency after 4 cycles, demonstrating good stability and reusability. Further experiments verified its high efficiency in degrading norfloxacin hydrochloride (84.9%) and rhodamine B (86.6%), confirming broad-spectrum applicability. This study develops a green, low-cost MnFe2O4/g-C3N4 catalyst with excellent cyclic stability, offering an efficient heterogeneous catalytic technology for remediating ROPs-contaminated wastewater. It also lays a theoretical and technical basis for the scale-up application of Fe/Mn-based carbon catalysts in industrial wastewater treatment, addressing the challenges of toxic catalyst leaching and high treatment costs.