Catalytic wet peroxide oxidation of benzoic acid over Fe/AC catalysts: Effect of nitrogen and sulfur co-doped activated carbon

Highlights: • The N, S co-doped AC was prepared by modification with thiourea. • The doped N and S improved the amount of Fe²⁺ on iron oxide surface. • The doped N and S improved the catalytic activity of Fe/AC catalyst. • The doped N and S helped prevent leaching of Fe. • The stability or reutilization of Fe/ACNS catalyst was fairly good. The parent activated carbon (ACP) was modified with urea and thiourea to obtain N-doped activated carbon (ACN) and N, S co-doped activated carbon (ACNS), respectively. Iron supported on activated carbon (Fe/ACP, Fe/ACN and Fe/ACNS) were prepared and worked as catalyst for catalytic wet peroxide oxidation of benzoic acid (BA). The catalysts were characterized by N₂ adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM), and their performance was evaluated in terms of benzoic acid and TOC removal. The results indicated the doped N and S improved the adsorption capacity as well as catalytic activity of activated carbon. Besides, the catalytic activity toward benzoic acid degradation was found to be enhanced by Fe/ACNS compared to that of Fe/ACP and Fe/ACN. The enhanced catalytic performance was attributed to the presence of the nitrogen and sulfur atoms may serve to improve the relative amount of Fe²⁺ on iron oxide surface and also help prevent leaching of Fe. It was also observed that the stability or reutilization of Fe/ACNS catalyst was fairly good.