Insight into mechanism of peroxydisulfate activation by natural pyrite: Participation of Fe(IV) and regulation of Fe(III)/Fe(II) cycle by sulfur species.
Chemosphere
; 314: 137657, 2023 Feb.
Article
in En
| MEDLINE
| ID: mdl-36581120
ABSTRACT
In this study, natural pyrite (NP) was used to activate peroxydisulfate (PDS) for imidacloprid (IMD) degradation. NP was characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Effects of key reaction parameters (NP dosage, PDS concentration and initial pH) and co-existing ions on IMD degradation in the NP/PDS system were investigated. Quenching experiments and electron spin resonance (ESR) tests identified the existence of sulfate radical (SO4â¢-), hydroxyl radical (â¢OH), singlet oxygen (1O2) and superoxide radical (O2â¢-). The cumulative concentration of SO4â¢- and â¢OH were quantified by the formation of benzoquinone (BQ) and p-hydroxybenzoic acid (HBA), respectively. Meanwhile, more than 60% of methylphenyl sulfoxide (PMSO) was selectively converted to methylphenyl sulfone (PMSO2), revealing that Fe(IV) was dominant in the NP/PDS system. The order of contribution of the three reactive species in the NP/PDS system was Fe(IV) > â¢OH > SO4â¢- (contributions of 1O2 and O2â¢- were negligible). Fe(II) released from NP played a crucial role in PDS activation, and sulfur species in NP could also boost Fe(III)/Fe(II) cycle and contribute to the generation of reactive species. Further, the possible degradation pathways of IMD have been proposed based on the detected intermediates using high-performance liquid chromatography-mass spectrometry (HPLC-MS), and the toxicity (including acute toxicity, developmental toxicity and mutagenicity) of these intermediates have been predicted using Toxicity Estimation Software Tool (T.E.S.T). Moreover, NP/PDS system was applied in four natural water bodies and IMD degradation efficiency reached more than 97% after adjusting the pH to 3. The fluorescence excitation-emission matrix (EEM) spectra showed that in addition to IMD, NP/PDS system could also remove other impurities.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Sulfur
/
Ferric Compounds
Language:
En
Journal:
Chemosphere
Year:
2023
Document type:
Article
Publication country:
ENGLAND
/
ESCOCIA
/
GB
/
GREAT BRITAIN
/
INGLATERRA
/
REINO UNIDO
/
SCOTLAND
/
UK
/
UNITED KINGDOM