Effect of goethite doping using elements with different preferential oxidation states for improved reversible phosphate adsorption

Journal Article (2023)
Author(s)

C. Belloni (TU Delft - RST/Fundamental Aspects of Materials and Energy, Wetsus, European Centre of Excellence for Sustainable Water Technology)

L. Korving (Wetsus, European Centre of Excellence for Sustainable Water Technology)

Geert Jan Witkamp (King Abdullah University of Science and Technology, TU Delft - BT/Environmental Biotechnology)

E.H. Brück (TU Delft - RST/Fundamental Aspects of Materials and Energy)

A.I. Dugulan (TU Delft - RST/Fundamental Aspects of Materials and Energy, TU Delft - RID/TS/Instrumenten groep)

Research Group
RST/Fundamental Aspects of Materials and Energy
Copyright
© 2023 C. Belloni, L. Korving, G.J. Witkamp, E.H. Brück, A.I. Dugulan
DOI related publication
https://doi.org/10.1016/j.jece.2023.110505
More Info
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Publication Year
2023
Language
English
Copyright
© 2023 C. Belloni, L. Korving, G.J. Witkamp, E.H. Brück, A.I. Dugulan
Research Group
RST/Fundamental Aspects of Materials and Energy
Issue number
5
Volume number
11
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Abstract

Phosphorus (P) removal from freshwater bodies to ultra-low concentrations is fundamental to prevent eutrophication, while its recovery is necessary to close the P usage cycle. Iron oxide-based adsorbents seem promising candidates, being abundant, cheap, and easy to synthesize compounds, with good affinity for P. Affinity is the key parameter when targeting ultra-low concentrations. Also, adsorbent regeneration and re-use is fundamental for the economic viability, hence the adsorbent stability is important. Goethite, (α-FeOOH), is one of the most stable iron (Fe3+) (hydr)oxide species, with higher affinity, but lower adsorption capacity (per kg) compared to other species. Doping could change goethite surface properties, to boost the adsorption capacity, while preserving the high stability and affinity for P. In this work, pure goethite was compared to goethite doped (5%at.) with different elements of different preferential oxidation states: Zn2+, Mn3+, and Zr4+. Doping was successfully achieved for all elements, albeit Zr showed a lower Fe substitution than targeted. Zn doping increased the goethite point of zero charge and adsorption capacity (per mass and per surface area), preserving the high affinity, while Mn- and Zr- doping displayed a decrease in all the parameters. These could be explained with surface protonation as a charge compensation mechanism in Zn2+-for-Fe3+ substitution. The regeneration test showed improved P recovery for Zr- and Zn-doped goethite. All samples remained stable throughout the whole process. This work provides promising insights on doping as a strategy to manipulate iron oxides surface properties and for developing a highly performing and long-lasting goethite-based adsorbent.