Degradation of tetracycline hydrochloride in aqueous via combined dielectric barrier discharge plasma and Fe-Mn doped AC

Abstract

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 Fe₂-Mn₁/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 Fe₂-Mn₁/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 O₃ might be catalyzed by Fe-Mn/AC catalyst to produce more ·OH. And more H₂O₂ 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.

Keywords: Degradation efficiency; Fe–Mn/AC; Non-thermal plasma; TCH; Wastewater.