Efficient
degradation of organic pollutants by oxidative radicals
is challenging in the complex soil environment because of the invalid
consumption of radicals by nontarget background substances and the
generation of secondary halogenated organic pollutants. Nonradical-based
oxidation is a promising pollutant removal method due to its high
selectivity and environmental adaptability. Herein, a biochar-supported
sheetlike CuO (e-CuO@BC) was developed, which exhibited efficient
activation of peroxydisulfate (PDS) via nonradical pathways. The activation
mechanisms were identified as (i) formation of surface-bonding active
complexes via an outer-sphere interaction between e-CuO@BC and PDS
and (ii) the continuous generation of 1O2 by
the cycling of the Cu(I)/Cu(II) redox couple. In addition, the activation
of PDS primarily occurred at the crystal facet (001) of e-CuO occupied
by Cu atoms and was well facilitated by the Cu–O–C bond,
which induced electron-rich centers around CuO. Two oxidative species
from PDS activation, including surface-bonding active complexes and 1O2, showed a highly selective degradation toward
electron-rich pollutants. Moreover, a highly efficient mineralization
of organic pollutants and an effective inhibition on the generation
of toxic byproducts (i.e., halogenated organics) was indicated by
the intermediate and final degradation products. This study provides
a comprehensive understanding of the heterogeneous activation process
of PS by the e-CuO@BC catalyst for electron-rich organic pollutant
removal.
The bimetallic spinel oxides have broad application prospects in pollution control by advanced oxidation processes. However, despite extensive efforts, the available commercial catalysts for soil contaminant degradation still suffer from inferior activity, low selectivity and poor longevity. Herein, we proposed an efficient strategy for boosting the intrinsic activities of sulfur-doped CuFe2O4/BC by defect engineering of dual vacancies. It is experimentally demonstrated that both the pseudo first-order rate constant and longevity of the sulfur-doped CuFe2O4/BC+PDS system for organics degradation have been promoted twice. Moreover, this system exhibits strong selective adsorption-oxidation capability towards hydrophobic organic contaminants. Theoretical calculations revealed that the incorporation of S-doping into the system plays a substantial role in the regulation of interface energetics and the enhancement of Fe-O covalency. This effectively facilitates electron transfer between metal redox pairs, culminating in high PDS utilization efficiency. This work offers an insightful understanding for collaboratively stimulating the intrinsic activity of the catalyst for soil remediation.
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