Investigation of the efficacy of graphite-sulfur iron tailing composite catalysts for activation of peroxydisulfate for rhodamine B degradation

Herein, a novel graphite/sulfur iron tailing composite was applied as a peroxydisulfate (PDS) activator for rhodamine B (RhB) degradation in the water. The superior catalytic efficiency of graphite/sulfur iron tailing was achieved through radical (SO₄^•− and •OH) and non-radical (¹O₂) processes according to the radical quenching experiments and electron paramagnetic resonance analysis. The carbonyl group and Fe species were the main active sites on the surface of graphite/sulfur iron tailing, which was demonstrated by combining Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and reaction kinetic experiments, and a possible degradation mechanism was also proposed. Overall, activated with 0.30 g/L of C-1, PDS achieved a 94.8% removal rate for RhB and maintained a removal rate of over 85% even after five consecutive operation cycles, and this study will benefit the application of iron/carbon composite materials in practical water treatment.