Cation adsorption in TiO$_2$ nanotubes : implication for water decontamination

Selmani, Atiđa (author), Siboulet, Bertrand (author), Špadina, Mario (author), Foucaud, Yann (author), Dražić, Goran (author), Radatović, Borna (author), Korade, Karla (author), Nemet, Ivan (author), Kovačević, Davor (author), Dufrêche, Jean-François (author), Bohinc, Klemen (author)

TiO$_2$ nanotubes constitute very promising nanomaterials for water decontamination by the removal of cations. We combined a range of experimental techniques from structural analyses to measurements of the properties of aqueous suspensions of nanotubes, with (i) continuous solvent modeling and (ii) quantum DFT-based simulations to assess the adsorption of Cs$^+$ on TiO$_2$ nanotubes and to predict the separation of metal ions. The methodology is set to be operable under realistic conditions, which, in this case, include the presence of CO$_2$ that needs to be treated as a substantial contaminant, both in experiments and in models. The mesoscopic model, based on the Poisson−Boltzmann equation and surface adsorption equilibrium, predicts that H$^+$ ions are the charge- determining species, while Cs$^+$ ions are in the diffuse layer of the outer surface with a significant contribution only at high concentrations and high pH. The effect of the size of nanotubes in terms of the polydispersity and the distribution of the inner and outer radii is shown to be a third-order effect that is very small when the nanotube layer is not very thick (ranging from 1 to 2 nm). Besides, DFT-based molecular dynamics simulations demonstrate that, for protonation, the one-site and successive association assumption is correct, while, for Cs$^+$ adsorption, the size of the cation is important and the adsorption sites should be carefully defined.

• Language: English
• Keywords: adsorption, charge inhomogeneities, nanotubes, potentiometric acid−base titration, surface charge, ions, oxides, titration
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: ZF - Faculty of Health Sciences
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: Str. 12711-12725
• Numbering: Vol. 6, iss. 14
• PID: 20.500.12556/RUL-152641
• UDC: 544.723
• ISSN on article: 2574-0970
• DOI: 10.1021/acsanm.3c00916
• COBISS.SI-ID: 159591171
• Publication date in RUL: 01.12.2023

Record is a part of a journal

• Title: ACS applied nano materials
• Shortened title: ACS appl. nano mater.
• Publisher: American Chemical Society
• ISSN: 2574-0970
• COBISS.SI-ID: 32649255

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: adsorpcija, nehomogenosti naboja, nanocevke, potenciometrična kislinsko-bazična titracija, površinski naboj