Enhanced degradation of Rhodamine B by pre-magnetized Fe0/PS process: Parameters optimization, mechanism and interferences of ions

An efficient heterogeneous catalyst, pre-magnetized Fe 0 (pre-Fe 0 ) could significantly activate persulfate (PS) to remove Rhodamine B (RhB). The effect of pH, Fe 0 and PS dose on the RhB removal in the pre-Fe 0 /PS and Fe 0 /PS processes were investigated, and optimized by response surface methodology (RSM) to analyze the rate constants of the RhB removal in the pre-Fe 0 /PS process and Fe 0 /PS process ( f ). High RhB removal was obtained at low pH and high dose of Fe 0 and PS in both systems. Low Fe 0 and high PS dose and large pH would result in big value of f , and the simulated maximum f of 44.3 was achieved at 2 mM Fe 0 , 16 mM PS and pH 9. The synergetic factor of pre-Fe 0 /PS (45.6) was larger than that of Fe 0 /PS (21.4). The pre-Fe 0 /PS process presented 2.1–37.5 folds enhancement than the Fe 0 /PS process for the degradation of RhB. The RhB removal in the pre-Fe 0 /PS process was 1.5–11.2 folds enhancement than that of the Fe 0 /PS process in the presence of different anions and cations. Scanning Electron Microscope (SEM) results and the larger intensity of DMPO-SO 4 − adduct signal in the Electron Paramagnetic Resonance (EPR) confirmed the primary role of sulfate radicals generated from the reaction of PS with Fe 0 in the contaminant degradation. The pre-Fe 0 /PS process exhibited advantages over other processes to remove RhB in terms of contaminant removal, working pH range and chemical dose. Therefore, the pre-Fe 0 /PS process is a cost-effective approach for degrading RhB.