1 research outputs found
Enhanced Oxidative and Adsorptive Removal of Diclofenac in Heterogeneous Fenton-like Reaction with Sulfide Modified Nanoscale Zerovalent Iron
Sulfidation of nanoscale zerovalent
iron (nZVI) has shown some
fundamental improvements on reactivity and selectivity toward pollutants
in dissolved-oxygen (DO)-stimulated Fenton-like reaction systems (DO/S-nZVI
system). However, the pristine microstructure of sulfide-modified
nanoscale zerovalent iron (S-nZVI) remains uncovered. In addition,
the relationship between pollutant removal and the oxidation of the
S-nZVI is largely unknown. The present study confirms that sulfidation
not only imparts sulfide and sulfate groups onto the surface of the
nanoparticle (both on the oxide shell and on flake-like structures)
but also introduces sulfur into the Fe(0) core region. Sulfidation
greatly inhibits the four-electron transfer pathway between Fe(0)
and oxygen but facilitates the electron transfer from Fe(0) to surface-bound
FeÂ(III) and consecutive single-electron transfer for the generation
of H<sub>2</sub>O<sub>2</sub> and hydroxyl radical. In the DO/S-nZVI
system, slight sulfidation (S/Fe molar ratio = 0.1) is able to nearly
double the oxidative removal efficacy of diclofenac (DCF) (from 17.8
to 34.2%), whereas moderate degree of sulfidation (S/Fe molar ratio
= 0.3) significantly enhances both oxidation and adsorption of DCF.
Furthermore, on the basis of the oxidation model of S-nZVI, the DCF
removal process can be divided into two steps, which are well modeled
by parabolic and logarithmic law separately. This study bridges the
knowledge gap between pollutant removal and the oxidation process
of chemically modified iron-based nanomaterials