Removal of Rhodamine B during the corrosion of zero valent tungsten via a tungsten species-catalyzed Fenton-like system

Abstract

• The nZVW/H 2 O 2 system effectively degraded RhB. • The stepwise oxidation of nZVW can generate low valence tungsten species. • The corrosion of nZVW can produce H 2 O 2. • ·OH was produce via Fenton-like system between tungsten species and H 2 O 2. • RhB degradation pathways were proposed based on the variation of intermediates. Rhodamine B (RhB) removal in a tungsten species-catalyzed Fenton-like system using nanoscale zero valent tungsten (nZVW) was investigated. The nZVW system can effective remove RhB in oxygenated water, and the nZVW/H 2 O 2 system significantly enhances the RhB removal. Mechanism investigation shows that hydroxyl radical (·OH) is the primary reactive oxidant for removing RhB in both systems. The stepwise oxidation of nZVW can release reactive tungsten species and produce H 2 O 2 by electron transfer from W 0 or low valent tungsten species to O 2 , and ·OH was then formed via a Fenton-like reaction between low valent tungsten species and H 2 O 2 . The addition of H 2 O 2 in the nZVW/H 2 O 2 system can increase the RhB removal ratio by accelerating nZVW corrosion and enhancing the Fenton-like reaction. Moreover, higher pH inhibits the RhB removal due to the consumption of reactive tungsten species by OH − , and both higher nZVW and H 2 O 2 dosages can enhance the RhB removal. RhB degradation pathways in the nZVW/H 2 O 2 system are proposed involving N-de-ethylation, chromophore cleavage, ring open, and mineralization. In addition, the present study puts forward a new water treatment technique and contributes to understand the role of tungsten species in advanced oxidation processes.