TESFA, Marawit; DIA, Aline; MAHÉ, Fabrice; JANOT, Noémie; MARSAC, Rémi

doi:10.1021/acs.est.3c04965

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TESFA, Marawit
Géosciences Rennes [GR]

DIA, Aline
Géosciences Rennes [GR]

MAHÉ, Fabrice
Institut de Recherche Mathématique de Rennes [IRMAR]

Langue

Article de revue

Ce document a été publié dans

Environmental Science and Technology. 2023-08-15, vol. 57, n° 32, p. 12053-12062

American Chemical Society

Résumé en anglais

Spectrophotometric acid–base titration is a simple and powerful technique to evaluate the properties of proton binding sites of natural organic matter (NOM) at environmentally relevant concentrations. However, it is challenging to quantify the chemical charges (Q) carried by NOM at these concentrations. Based on a previous work, which relates the variation of Q with the specific UV–vis differential absorbance (ΔAλ,pH) at a given wavelength (λ) and pH of a dissolved NOM sample, the present work proposes a method to investigate any NOM sample. It determines specific features in the absorbance spectra attributed to proton-inert chromophores (A0,λ) and to the deprotonation processes of carboxylic (A1,λ) and phenolic groups (A2,λ). It enables to select sample-specific wavelength (λmid), where both these functional groups significantly contribute to the variation of absorbance with pH. The linear regression analysis of Aλmid,pH vs Q for various NOM reference samples evidenced that the sample-specific slope (SNOM) and intercept (INOM) were related to the intrinsic spectroscopic properties of the sample (A0,λmid, A1,λmid, and A2,λmid). This approach can thus be used to approximate the Q values of the NOM samples at environmentally relevant concentrations: a pre-requisite for predicting the fate and behavior of metal ions in natural systems.< Réduire

Mots clés en anglais

natural organic matter

acid−base functional groups

proton titration

absorbance spectra

URI

https://oskar-bordeaux.fr/handle/20.500.12278/195087

DOI

http://dx.doi.org/10.1021/acs.est.3c04965

Projet Européen

FEDER

Project ANR

Le devenir des contaminants est contrôlé par la spéciation de la matière organique colloïdale - ANR-18-CE01-0008

Origine

Importé de hal

Unités de recherche

Interactions Soil Plant Atmosphere (ISPA) - UMR 1391