Novel NiCo2S4/CS membranes as efficient catalysts for activating persulfate and its high activity for degradation of nimesulide

In recent years, sulfate radicals-based advanced oxidation process becomes an effective and common technique for elimination of emerging organic contaminants. In this study, novel NiCo2S4/CS composite was synthesized through hydrothermal method, with the physicochemical properties being characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microcopy (TEM), Brunauer-Emmett-Teller (BET) and Fourier Transform infrared spectroscopy (FT-IR). Then, NiCo2S4/CS composite acted as catalyst to activate PS for nimesulide degradation. The results showed that NiCo2S4/CS composite owned the highest activity compared with pure NiCo2S4 and carbon sphere (CS), achieving 92% nimesulide degradation in 10 min with 0.1 g/L catalyst and 0.4 g/L persulfate. Furthermore, the NiCo2S4/CS membrane was fabricated by vacuum filtration, and 94% and 80% above nimesulide degradation were realized for the first time and after six times repeated experiment, which demonstrated that the catalyst was convenient to achieve recovery and reusability. In addition, the radical quenching experiment, XPS and the electrochemical methods (LSV and EIS) were measured to investigate the possible mechanism pathway, the results of which showed that both the non-radical pathway and radical pathway might attribute to nimesulide degradation, while the SO4− remained the dominant species. This research provided a novel sulfide NiCo2S4/CS membrane for the oxidative technique for emerging organic contaminants in water treatment.