A novel strategy of pulsed electro-assisted pyrite activation of peroxymonosulfate for the degradation of tetracycline hydrochloride

Abstract In order to overcome the complexity and high cost of preparation of iron-based modified catalyst, a novel process of natural pyrite (FeS2) superimposed pulsed electro-assisted activation peroxymonosulfate (PMS) for contamination treatment was developed. Tetracycline hydrochloride (TCH) was selected as the target pollutant because of its persistence and high drug-resistance toxicity. Firstly, the optimum parameters (pulse current intensity, duty cycle, pH, PMS concentration) were determined by different conditional experiments. Then, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize pyrite before and after the reaction. And electron spin resonance (ESR) and quenching experiment were used to discern the active species in the reaction processes. The results showed that pyrite could effectively activate PMS to degrade into hydroxyl radicals ( OH) and sulfate radicals (SO4 −) to treatment contamination. In addition, the pulsed electro-assisted addition could weaken concentration polarization, improve TCH removal efficiency to 93%, and reduce energy consumption. More importantly, pulsed current was better than the direct current for converting S O 4 2 - to S O 4 · - . And Fe(III) can be converted to Fe(II) through the action of electrons and S22− in the pulse electro-assisted pyrite activation of PMS process. These findings provide new insights into PMS activation by iron-based catalyst and electrochemistry.