Neglected but Efficient
Electron Utilization Driven
by Biochar-Coactivated Phenols and Peroxydisulfate: Polyphenol Accumulation
Rather than Mineralization
Posted on 2023-03-18 - 13:03
We report an unrecognized but efficient nonradical mechanism
in
biochar-activated peroxydisulfate (PDS) systems. Combining a newly
developed fluorescence trapper of reactive oxygen species with steady-state
concentration calculations, we showed that raising pyrolysis temperatures
of biochar (BC) from 400 to 800 °C remarkably enhanced trichlorophenol
degradation but inhibited the catalytic production of radicals (SO4•– and •OH) in
water and soil, thereby switching a radical-based activation into
an electron-transfer-dominated nonradical pathway (contribution increased
from 12.9 to 76.9%). Distinct from previously reported PDS* complex-determined
oxidation, in situ Raman and electrochemical results
of this study demonstrated that the simultaneous activation of phenols
and PDS on the biochar surface triggers the potential difference-driven
electron transfer. The formed phenoxy radicals subsequently undergo
coupling and polymerization reactions to generate dimeric and oligomeric
intermediates, which are eventually accumulated on the biochar surface
and removed. Such a unique nonmineralizing oxidation achieved an ultrahigh
electron utilization efficiency (ephenols/ePDS) of 182%. Through biochar molecular
modeling and theoretical calculations, we highlighted the critical
role of graphitic domains rather than redox-active moieties in lowering
band-gap energy to facilitate electron transfer. Our work provides
insights into outstanding contradictions and controversies related
to nonradical oxidation and inspiration for more oxidant-saving remediation
technologies.
CITE THIS COLLECTION
Dou, Jibo; Tang, Yao; Lu, Zhijiang; He, Guangzhi; Xu, Jianming; He, Yan (2023). Neglected but Efficient
Electron Utilization Driven
by Biochar-Coactivated Phenols and Peroxydisulfate: Polyphenol Accumulation
Rather than Mineralization. ACS Publications. Collection. https://doi.org/10.1021/acs.est.3c00022
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AUTHORS (6)
JD
Jibo Dou
YT
Yao Tang
ZL
Zhijiang Lu
GH
Guangzhi He
JX
Jianming Xu
YH
Yan He
KEYWORDS
work provides insightssup >• supsaving remediation technologiesreactive oxygen speciesraising pyrolysis temperaturespolyphenol accumulation rathergraphitic domains ratherefficient nonradical mechanismdominated nonradical pathwaystate concentration calculationsbiochar molecular modelingpreviously reported pdsbiochar surface triggersfacilitate electron transferdriven electron transferbiochar surfacenonradical oxidationtheoretical calculationsthereby switchingstudy demonstratedsitu simultaneous activationpotential differencepolymerization reactionsoutstanding contradictionsoligomeric intermediateslowering bandgenerate dimericgap energyeventually accumulatedelectrochemical resultse determined oxidationcritical rolecontroversies relatedcontribution increasedcatalytic productionbased activationactive moieties182 %.