Zero-valent tungsten boosted Fenton-like oxidation (Fe(III)/ peroxydisulfate) towards long-lasting oxidation of carbamazepine: Performance and mechanism

The slow conversion of the Fe(III)/Fe(II) redox couple arising from Fe(III) accumulation strongly restricts the ongoing generation for reactive oxygen species (ROS) in Fenton/Fenton-like systems. Hereby, micron zero-valent tungsten (& mu;ZVW) was applied as a co-catalyst to boost Fe(III) reduction for promoting the Fenton-like activation of peroxydisulfate (PDS), and the oxidation capacity and reaction mechanism of & mu;ZVW/Fe(III)/PDS system are investigated with carbamazepine (CBZ) as the target pollutant. The results show that CBZ can be completely degraded by the & mu;ZVW/Fe(III)/PDS system within 30 min, & mu;ZVW exhibits exceptionally high stability for long -lasting CBZ oxidation during 10 cycling tests. According to a mechanistic analysis, the main ROS responsible for CBZ oxidation include high-valent iron (Fe(IV)), hydroxyl radicals, and sulfate radicals, meanwhile, & mu;ZVW can rapidly reduce Fe(III) into Fe(II) and further boost Fenton-like activation of PDS. Fe(III) and PDS can speed up the stepwise oxidation of & mu;ZVW to steadily release low-valence tungsten species, which can induce reduction of dissolved oxygen to produce H2O2 and donate electrons to cleave peroxide O-O bonds of H2O2 and PDS to produce ROS. In addition, the self-cleaning function of & mu;ZVW makes it efficient to remove CBZ was discovered. Therefore, the finding of this study proposes a novel co-catalyst to boost Fenton-like activation of PDS, which can promote the scientific advances in enhanced Fenton-like oxidation towards realistic use in water remediation.