High-Efficiency Simultaneous Oxidation of Organoarsenic
and Immobilization of Arsenic in Fenton Enhanced Plasma System
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Abstract
Roxarsone
(ROX), an organoarsenic compound serving as a common
feeding additive, is heavily utilized in the agricultural field and
brings about the potential risks of toxic inorganic arsenic contamination
in the ambient environment. In this study, the applicability of glow
discharge plasma (GDP) for simultaneous oxidation of organoarsenic
and immobilization of arsenic is unprecedentedly evaluated. The results
show that ROX can be effectively oxidized to inorganic arsenic, and
this performance is evidently dependent on energy input. Adding Fe(II)
can significantly enhance the oxidation of ROX mainly because of the
additional production of <sup>•</sup>OH via Fenton reaction
in GDP, accompanied by which the generated arsenic can be simultaneously
immobilized in one process. The immobilization of arsenic can be favorably
obtained at pH 4.0–6.0 and Fe(II) concentration ranging from
500 to 1000 μM. On the basis of the mineral compositions and
analysis (XRD/FTIR/XPS) of precipitate, a mechanism can be proposed
that the oxidation of Fe(II) by H<sub>2</sub>O<sub>2</sub> generated
in situ in GDP significantly accelerates ROX transformation to the
ionic As(V), which can immediately precipitate with Fe(III) ions or
be adsorbed on the ferric oxyhydroxides, forming amorphous ferric
arsenate-bearing ferric oxyhydroxides. As such, the present study
offer a new recipe for rapid decontamination of organoarsenic pollutants,
in which the hypertoxic species can be effectively removed from the
wastewater