Polyhydroquinone-Coated Fe3O4 Nanocatalyst for Degradation of Rhodamine B based on Sulfate Radicals

In this study, the polyhydroquinone/Fe3O4 (PHQ/Fe3O4) was synthesized as a heterogeneous catalyst to activate persulfate to effectively degrade Rhodamine B (RhB). The synthetic PHQ/Fe3O4 nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) nitrogen adsorption, and Fourier-transform infrared (FTIR) spectra. PHQ/Fe3O4 shows better catalytic performance and excellent reusability than PHQ and Fe3O4. The results indicated that PHQ/Fe3O4 maintains quinone units and the presence of the quinone moieties successfully accelerates the degradation compared to Fe3O4, owing to the role of quinone assisting the redox cycling of Fe. Effects of PHQ/Fe3O4 addition, persulfate concentration, pH, and temperature on the degradation efficiency of RhB by persulfate are examined in batch experiments. Increasing the temperature may significantly accelerate the RhB degradation, and the degradation is found to follow the pseudo-first-order kinetic model. On the basis of these findings, the possible mechanism of RhB degradation was proposed.