Three-dimensional (3D) electrochemical oxidation has emerged as a promising advanced oxidation process for wastewater treatment, owing to its high efficiency, environmental compatibility, and operational advantages. In this study, we developed a novel Fe/Mn co-loaded activated carbon (Fe/Mn-AC) particle electrode for the electrochemical oxidation of ammonium nitrogen NH 4 + -N) in wastewater. The as-prepared catalyst was systematically characterized through multiple analytical techniques including SEM-EDS, XRD, FTIR, XPS, and BET surface area analysis. Post-impregnation, SEM revealed maintained surface smoothness but reduced pore sizes, while BET measurements confirmed decreased surface area (from 732.38 to 650.83 m 2 /g), pore diameter (from 2.6 to 2.18 nm), and pore volume (from 0.43 to 0.37 cm 3 /g). XRD and XPS analyses identified iron and manganese oxides (Fe 2 O 3 , Fe 3 O 4 , Mn 2 O 3 , Mn 3 O 4 ) as the active phases. FTIR spectra exhibited characteristic bands of O–H (3462 cm −1 ), C–O (1571 cm −1 ), and C–C (1384 cm −1 ) in both AC and Fe/Mn-AC, with observable intensity variations after metal loading. Under optimized conditions (pH = 7, applied voltage = 14 V, Fe/Mn loading = 1 %, initial NH 4 + -N concentration = 100 mg/L), the 3D electrochemical system achieved an NH 4 + -N removal efficiency of 87.64 % with an energy consumption of 6.2 kW h/kg NH4+-N after 8 h of treatment. Radical quenching experiments confirmed the in-situ generation of hydroxyl radicals and electrons during the electrochemical process. The degradation mechanism study revealed that NH 4 + -N was primarily removed through indirect electro-oxidation pathways, with N 2 identified as the dominant end product.
Jian Cheng,Yirui Xie,Ying Wei,Dongrun Xie,Wenbo Sun,Ying Zhang,Menghong Li,Jiutao An
Dielectric barrier discharge (DBD) plasma coupled with Fe–Mn doped AC (Fe–Mn/AC) was used to enhance the degradation of tetracycline hydrochloride (TCH) wastewater. Fe–Mn/AC catalysts with different Fe/Mn molar ratios were prepared by hydrothermal method, and the physical and chemical properties of the samples were explored by different characterization techniques, including XRD, SEM , TEM and XPS. The results showed that the combination of DBD with Fe 2 –Mn 1 /AC system had the highest effect, and the degradation efficiency of TCH could reach 98.8 % after 15 min treatment, which was 25.5 % higher than that of DBD-only. With the increase of discharge voltage and catalyst dosage, the degradation efficiency of TCH promoted. And initial pH had little effect on the degradation of TCH. In the combined system, the Fe 2 –Mn 1 /AC catalyst could retain an excellent stability and reusability. The addition of dimethyl sulfoxide (DMSO) showed that ·OH participated in the TCH degradation. The generated O 3 might be catalyzed by Fe–Mn/AC catalyst to produce more ·OH. And more H 2 O 2 was produced in DBD-only system than that in DBD-catalytic system. Nine main degradation intermediate products in the combined system were detected by HPLC-MS, and three possible degradation pathways were proposed.
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