Voltammetric Characteristics of Hydrous Fe(III) Oxide Embedded into Nafion and Immobilised onto a Screen Printed Carbon Electrode: Binding of Arsenate versus Phosphate

Thulase Sivasothy, Nche George Ndifor-Angwafor , Frank Marken

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Nafion offers microporous channels of typically 1–4-nm diameter for cation exchange. Recently, it has been shown that these cation exchanger properties can be inverted to allow anion binding by pre-filling the hydrophilic channel structure. Here, pre-filling is performed with hydrous iron oxide and sensitivity towards anionic phosphate and arsenate analytes is investigated. After a period of phosphate/arsenate accumulation, the voltammetric response in aqueous 1 M NaNO 3 is obtained based on the Fe(III/II) redox process. The position of the peak at distinct potentials clearly reveals the presence of either phosphate or arsenate, presumably present in the form of FePO 4 and FeAsO 4. In the presence of mixtures of phosphate and arsenate, a competition of FePO 4 versus FeAsO 4 nucleation (within the Nafion microporous host) is suggested to result in a switch of phosphate detection at higher concentrations (ca. > 500 μM, solubility controlled) towards arsenate detection at lower concentrations (ca. < 500 μM, nucleation controlled). This phenomenon is suggested to be linked to the Ostwald step rule. [Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)3059-3067
Number of pages9
JournalJournal of Solid State Electrochemistry
Volume22
Issue number10
Early online date12 Jun 2018
DOIs
Publication statusPublished - 1 Oct 2018

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Keywords

  • Arsenate
  • Nafion
  • Nucleation
  • Phosphate
  • Sensor
  • Voltammetry

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Electrochemistry
  • Electrical and Electronic Engineering

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