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The fabrication of the carboxyl-modified CNT electrode was described. The electroanalytical investigation of sulfadiazine has been conducted in alkaline aqueous solution at the CNT electrode by voltammetry. Highly reproducible and well-defined cyclic voltammograms were obtained for sulfadiazine with a very good signal to background (S/B) ratio. However, no fouling of the electrode was observed at the CNT electrode within the experimental period of several hours, which illustrated that the CNT electrode was much better than traditional electrodes. Meanwhile, the detection of trace sulfadiazine in milk was also conducted by cyclic voltammetry with satisfactory ratio of recovery, indicating that the nanotube electrode can be used in routine monitoring of sulfadiazine residues in food.

To improve the activation efficiency of PMS to efficiently degrade antibiotic sulfadiazine (SD), herein, a Co@MoS₂ catalyst was prepared by a one-step hydrothermal process. The unique petal-like structure of MoS₂ enables the transition metal Co to achieve high dispersion and avoid agglomeration. Mo(IV) and unsaturated S accelerate the electron transfer between Co${}^{2+}$ and Co${}^{3+}$ to improve the cycling efficiency and thus realize the efficient activation of PMS. The results of active substance quenching experiment and ESR analysis show that the main active substance for the efficient degradation of SD by Co@MoS₂ is the non-radical ¹O₂, while the other three radicals $\cdot {\mathrm{\text{O}}}_2^{-}$, ⋅OH and ${\mathrm{\text{SO}}}_4^{•-}$ contribute significantly to the efficient degradation of SD. And after 5 cycles, the degradation could still be as high as 90%. The strong consolidation of Co on the petal-shaped sheet of MoS₂ ensures the stability of Co@MoS₂ catalyst.

The adsorption behavior of sulfadiazine (SDZ) onto hydrous manganese dioxide (HMO) is systematically investigated in this study. SDZ removal is highly pH dependent and ionic strength has slightly effect on the uptake of SDZ. The Webber-Morris equations model shows that SDZ adsorption by HMO is controlled jointly by the film-diffusion and intraparticle-diffusion. The adsorption isotherms at varied temperatures are well described by Langmuiir model, and thermodynamic parameters (∆H>0, ∆S>0 and ∆G<0) reveal that the adsorption of SDZ on HMO is spontaneous and endothermic process. The uptake process of SDZ by HMO is mainly ascribed to the hydrogen bonding between the nitrogen (N) of aniline and the surface hydroxyl groups of HMO.