Air-cathode
fuel cell (AC-FC) technology provides a facile way
for fabricating Fe3O4/graphite composite by
in situ utilizing the FeII in acid mine drainage (AMD).
Herein, surface modification of the graphite support is suggested
to be an effective strategy to enhance electro-Fenton (EF) catalytic
activity of the Fe3O4/graphite composite prepared
from AMD. Four surface modification methods, including H2O2 treatment, electro-oxidation treatment, KOH treatment,
and N2H4 treatment, are applied on commercial
graphite felt (GF). Structures and properties of the modified GFs
are characterized, and EF catalytic activities of corresponding Fe3O4/GF composites prepared from synthetic AMD are
evaluated. The results demonstrate that surface modification of GF
not only improves the electro-oxidation of FeII in AC-FC
but also promotes the electro-generation of H2O2 in the heterogeneous EF process. Notably, the concentration of H2O2 generated on N2H4-treated
GF (GF-N2H4) is more than three times that generated
on unmodified GF (GF-Raw), and iron content in the prepared Fe3O4/GF-N2H4 composite is more
than twice that in the Fe3O4/GF-Raw composite.
Application of GF-N2H4 to the treatment of real
AMD greatly enhances the recovery efficiency of FeII as
Fe3O4. The Fe3O4/GF-N2H4 composite prepared from real AMD displays high
catalytic activity and good stability in the heterogeneous EF process
for mineralizing a variety of refractory organic contaminants.
The
cleavage of C–O–C linkage is a critical step
in the degradation of diaryl ether contaminants and lignin, which
holds great significance of environmental protection and lignocellulosic
biomass utilization. Traditional chemical cleavage methods require
harsh operation conditions such as using strong acids/bases and/or
at high temperatures. Herein, we report an anodic oxidation process
on the carbon electrode, which displays high efficiency for the selective
electrochemical cleavage of the C–O bond in diaryl ethers under
room conditions. Application of such an electrochemically oxidative
cleavage approach on triclosan, 4-hydroxydiphenyl ether, 4,4′-dihydroxydiphenyl
ether, and rhodamine B demonstrates high reaction selectivity to the
aryl C–O bond. Notably, the production of quinone compounds
as the main products is highlighted to open the opportunity for acquiring
quinone derivatives from diaryl ethers. The anodic oxidation process
is found to apply a direct electrochemical oxidation pattern under
the catalysis of surface oxygenated groups of the carbon electrode.
Enlightened by this finding, a surface modification strategy of the
carbon electrode is proposed to accelerate the oxidative cleavage
of diaryl ethers. The anodic oxidation process not only provides a
novel way to design economic routes for the removal of diaryl ether
contaminants but also has potential application in degrading lignocellulosic
biomass for the production of value-added chemicals.
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