MoS2-assisted iron-driven peroxydisulfate activation for green and sustainable water purification

Abstract

Peroxydisulfate (PDS)-based advanced oxidation processes are promising for reclaimed water treatment; however, they are often hindered by high energy demands, costly and complex catalyst synthesis, and the requirement for external energy inputs. Commercially available materials, commercial catalytic iron powder (CCI) and MoS2 were selected to activate PDS (CCI/MoS2/PDS system) for the high-concentration dye wastewater (Acid Orange 7, AO7) degradation within 5 minutes. CCI generates Fe2+ and Fe3+, while MoS2 facilitates the rate-limiting Fe3+/Fe2+ cycle. The reaction rate of CCI/MoS2/PDS system is approximately 2 times higher than without co-catalyst. Therefore, the system can efficiently generate a variety of reactive species (e.g., radicals) for the degradation of organic wastewater. The primary active species responsible for the degradation of AO7 in the CCI/MoS2/PDS system was sulfate radical (SO4•-). Following both a small-scale continuous-flow experiment and a pilot-scale continuous-flow reactor equipped with a catalyst-filled column, the system maintained high efficiency and catalytic activity, enabling long-term, stable, and effective removal of AO7. Remarkably, the CCI/MoS2/PDS system has an operating cost of only US$ 0.16 per ton of wastewater, highlighting its great potential for large-scale industrial applications. This work provides valuable guidance for the development of green, low-cost and efficient PDS-activation systems for industrial wastewater treatment.