Central Role of Bicarbonate Anions in Charging Water/Hydrophobic Interfaces Auteur(s): Yan Xibo, Delgado Marco, Aubry Julien, Gribelin Olivier, Stocco A., Boisson-da Cruz Fernande, Bernard Julien, Ganachaud Francois (Article) Publié: Journal Of Physical Chemistry Letters, vol. 9 p.96-103 (2018) Texte intégral en Openaccess : Ref HAL: hal-02010370_v1 DOI: 10.1021/acs.jpclett.7b02993 WoS: 000419750900016 Exporter : BibTex | endNote 16 Citations Résumé: Aqueous interfaces are ubiquitous in Nature and play a fundamental role in environmental or biological processes or modern nanotechnologies. These interfaces are negatively charged, and despite several decades of research, the rationale behind this phenomenon is still under debate. Two main controversial schools of thought argue on this issue; the first relies on the adsorption of hydroxide anions on hydrophobic surfaces, whereas the second one supports a self-rearrangement of water molecules at the interface bearing hydronium ions. Here, we report on two series of independent experimental studies (nanoprecipitation and interfacial tension measurements) that demonstrate that in the pH 5–10 range the negative interfacial charge of the colloids mostly stems from bicarbonate ions, whereas at lower and higher pH, protons and hydroxide ions contribute, with bicarbonate ions, to the interfacial charging. This new interpretation complies with previous studies and opens new perspectives to this striking physical chemical issue. |