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 off, and the simulated maximumfof 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-SO4- 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.