Application of Mo2C for enhancement of co-catalytic performance of Fe3+/PS based fenton-like reaction in degrading tetracycline hydrochloride

In this work, molybdenum carbide (Mo2C) was innovatively introduced into the trivalent iron/sodium persulfate (Fe3+/PS) based Fenton-like process for tetracycline hydrochloride (TC) degradation, and its co-catalytic performance was compared with three typical metal sulfides (tungsten disulfide (WS2), molybdenum sulfide (MoS2), and cobalt disulfide (CoS2)). Results indicated that the Mo2C/Fe3+/PS system had significantly higher rates of TC removal (0.3054 min−1) and Fe(III) reduction (1.6622 min−1) compared to the three metal sulfide systems. The Mo2C/Fe3+/PS system could be adapted to a wide pH range (2.7–8.5), and Mo2C still had excellent co-catalytic performance after five cycles. X-ray photoelectron spectroscopy demonstrated the presence of Mo(II) and Mo(IV) on the surface of Mo2C, which can directly reduce Fe3+, thus significantly improving the reaction efficiency. Quenching and Electron Paramagnetic Resonance experiments demonstrated that four oxidative species were involved in Mo2C/Fe3+/PS system. The continuous reduction of Fe(III) by Mo2C contributed to the significant enhancement of PS activation in the Mo2C/Fe3+/PS system. Moreover, the presence of water matrix such as chloride ions (Cl−), nitrate ions (NO3−), and humic acid (HA) had almost no significant effect on TC degradation, indicating that the Mo2C/Fe3+/PS system can work effectively under complex conditions. In summary, this study provides a novel and efficient strategy to accelerate the Fe(III)/Fe(II) cycle and activate PS for TC degradation, which is expected to advance the development of the Fenton-like process.