Photo-generation of mercury cold vapor mediated by graphene quantum dots/TiO2 nanocomposite: On line time-resolved speciation at ultra-trace levels

Tipo
Artigo
Data de publicação
2020
Periódico
Analytica Chimica Acta
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7
Autores
Miranda-Andrades J.R.
Letichevsky S.
Gonzalez Larrude D.R.
Aucelio R.Q.
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© 2020 Elsevier B.V.Mercury speciation was achieved using a nanocomposite, consisting of graphene quantum dots (GQDs) and TiO2 nanoparticles, to mediate photo-degradation of mercurial species into the Hg cold vapor detected by atomic spectrometry. Sample solution (containing Hg2+, CH3CH2Hg, and CH3Hg at hundreds of ng L−1) was placed in quartz tube containing formic acid solution (2% v/v) and microliter aliquot of GQDs/TiO2 nanocomposite dispersion (0.6 mg of nanocomposite). The tube was placed inside a photochemical reactor then, adapted to the mercury-dedicated spectrometer. Quantitative speciation was achieved taking advantage of the differences in UV photodegradation kinetics: Hg2+ (5 min), CH3CH2Hg (9 min) and CH3Hg (13 min). Gas-chromatography cold vapor atomic fluorescence spectrometry was used to confirm the evolution of the reactions over time during photo-reaction. The limits of detection were 10 ng L−1 for CH3CH2Hg and 7 ng L−1 for Hg2+ and CH3Hg.
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Atomic fluorescence spectrometry , Atomic spectrometry , Limits of detection , Mercury speciations , Nanocomposite dispersions , Photochemical reactor , Photodegradation kinetics , Ultra-trace levels
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