BoneChar Mediated Dechlorination of Trichloroethyleneby Green Rust
Figshare documentation (Figshare (United Kingdom))(2020)
摘要
Biochars
function as electron transfer mediators and thus catalyze
redox transformations of environmental pollutants. A previous study
has shown that bone char (BC) has high catalytic activity for reduction
of chlorinated ethylenes using layered Fe(II)–Fe(III) hydroxide
(green rust) as reductant. In the present study, we studied the rate
of trichloroethylene (TCE) reduction by green rust in the presence
of BCs obtained at pyrolysis temperatures (PTs) from 450 to 1050 °C.
The reactivity increased with PT, yielding a maximum pseudo-first-order
rate constant (k) of 2.0 h–1 in
the presence of BC pyrolyzed at 950 °C, while no reaction was
seen for BC pyrolyzed at 450 °C. TCE sorption, specific surface
area, extent of graphitization, carbon content, and aromaticity of
the BCs also increased with PT. The electron-accepting capacity (EAC)
of BC peaked at PT of 850 °C, and EAC was linearly correlated
with the sum of concentrations of quinoid, quaternary N, and pyridine-N-oxide
groups measured by XPS. Moreover, no TCE reduction was seen with graphene
nanoparticles and graphitized carbon black, which have high degrees
of graphitization but low EAC values. Further analyses showed that
TCE reduction rates are well correlated with the EAC and the C/H ratio
(proxy of electrical conductivity) of the BCs, strongly indicating
that both electron-accepting functional groups and electron-conducting
domains are crucial for the BC catalytic reactivity. The present study
delineates conditions for designing redox-reactive biochars to be
used for remediation of sites contaminated with chlorinated solvents.
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关键词
dechlorination
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