Multi-catalysis of glow discharge plasma coupled with FeS2 for synergistic removal of antibiotic.

Fe-based composites improved the energy utilization efficiency of plasma for removing contaminants through multi-catalysis have received much attention. However, the energy efficiency and catalytic activity are compromised by the slow transformation from Fe (Ⅲ) to Fe (Ⅱ). Here, given the electron-donating ability of reducing sulfur species, as well as the acidic environment generated by FeS2, single FeS2 was introduced into the glow discharge plasma (GDP) reactor for the removal of tylosin (TYL). The results showed that a significant synergistic effect between FeS2 and GDP improved the energy efficiency of plasma and the removal efficiency of TYL (99.7%). FeS2 boosted the generation of radicals (·OH, ·O2-) and nonradicals (h+, e-) rather than H2O2 and O3, which played an important role in TYL abatement. Moreover, the electrons donating sulfur and iron species from FeS2 can accelerate the conversion of Fe(III) to Fe(II), which was conducive to the generation of radicals. Besides, acid solution self-adjustment resulted from the oxidation of FeS2 improved heterogeneous Fenton reaction, the oxidation potential of ·OH and adsorption of positive charged TYL. The plausible degradation pathways of TYL were proposed in GDP/FeS2 system. In summary, enhanced removal of TYL was mainly attributed to the catalytic pathway altered by FeS2 through high-energy electrons, photocatalysis, heterogeneous Fenton and O3 catalysis in the GDP system simultaneously. The strategy of integrating GDP with FeS2 proposed in this work is expected to offer a feasible and potential technique for organic wastewater treatment.