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- Title
Evaluation by Means of Electrochemical Impedance Spectroscopy of the Transport of Phosphate Ions through a Heterogeneous Anion-Exchange Membrane at Different pH and Electrolyte Concentration.
- Authors
Rotta, Eduardo Henrique; Martí-Calatayud, Manuel César; Pérez-Herranz, Valentín; Bernardes, Andréa Moura
- Abstract
Electrodialysis is an innovative technique to reclaim phosphates from municipal wastewater. However, chemical reactions accompany the transport of these ions through ion-exchange membranes. The present study investigates the dependence of these phenomena on the initial pH and concentration of the phosphate-containing solution using a heterogeneous anion-exchange membrane. Linear sweep voltammetry, electrochemical impedance spectroscopy, and chronopotentiometry experiments were conducted for different phosphate-containing systems. For the most diluted solution, two limiting current densities (ilim) have been observed for pH 5 and 7.2, while only one ilim for pH 10, and correlated with the appearance of Gerischer arcs in EIS spectra. For pH 7.2, sub-arcs of Gerischer impedance were separated by a loop, indicating the involvement of the membrane functional groups. Increasing the phosphate concentration changed the system's characteristics, reporting a single ilim. In the EIS spectra, the absence of Gerischer elements determined the attenuation of chemical reactions, followed by the development of a diffusion boundary layer, as indicated by the finite-length Warburg arcs. Chronopotentiometry clarified the mass transport mechanism responsible for distorting the diffusion boundary layer thickness at lower concentrations. The obtained results are expected to contribute to the phosphates recovery using electrodialysis in the most varied conditions of pH and concentration available in the environment.
- Subjects
IMPEDANCE spectroscopy; ION-permeable membranes; ELECTRODIALYSIS; CHEMICAL reactions; BOUNDARY layer (Aerodynamics); FUNCTIONAL groups
- Publication
Water (20734441), 2023, Vol 15, Issue 1, p9
- ISSN
2073-4441
- Publication type
Article
- DOI
10.3390/w15010009