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High affinity lanthanum doped iron oxide nanosheets for phosphate removal

Lu, Changyong ; Klementiev, Konstantin LU ; Hassenkam, Tue ; Qian, Wenjie ; Ai, Jing and Chr. Bruun Hansen, Hans (2021) In Chemical Engineering Journal 422.
Abstract

Phosphorus induced eutrophication of freshwaters is one of the great global challenges. As the critical threshold concentration for eutrophication is very low, there is a strong need for development of phosphate sorbents with high affinity and selectivity. Single sheet iron oxide (SSI), a nanomaterial prepared from oxidation and exfoliation of layered iron(II)-iron(III) hydroxide (green rust), is a fast reacting and promising sorbent. Phosphate sorption affinity and selectivity may be improved by incorporation of lanthanum (La) in the structure. Lanthanum was added during SSI synthesis resulting in La-SSIs with 0 to 22.5 wt% of La content. XPS and EXAFS showed all La was present as La(OH)3 nanoclusters between iron hydroxide... (More)

Phosphorus induced eutrophication of freshwaters is one of the great global challenges. As the critical threshold concentration for eutrophication is very low, there is a strong need for development of phosphate sorbents with high affinity and selectivity. Single sheet iron oxide (SSI), a nanomaterial prepared from oxidation and exfoliation of layered iron(II)-iron(III) hydroxide (green rust), is a fast reacting and promising sorbent. Phosphate sorption affinity and selectivity may be improved by incorporation of lanthanum (La) in the structure. Lanthanum was added during SSI synthesis resulting in La-SSIs with 0 to 22.5 wt% of La content. XPS and EXAFS showed all La was present as La(OH)3 nanoclusters between iron hydroxide layers and on the surface of SSI. The sorbent showed fast phosphate sorption with 90% completion within 30 min and high stability with minimal La leaching. All La-SSI nanomaterials showed better sorption affinity than non-doped SSI, and the La-SSI with the highest La content showed an extreme affinity with Kd of 105 L/kg at solution concentration of 0.1 mg P/L. The sorption affinity was not seriously affected by pH. The La-SSIs showed high selectivity for phosphate with<10% reduction in phosphate sorption in presence of co-existing solutes (Cl–, NO3–, SO42-, HCO3– and humic acid). Similar high affinity and selectivity was seen for phosphate sorption in real natural waters. The main phosphate sorption mechanism is attributed to inner sphere Fe-O-P and La-O-P surface complexation. In conclusion La doping turns SSI into a high-affinity and selectivity sorbent that has potential for polishing low-phosphate yet eutrophying natural waters such as drainage and lake waters.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Lanthanum coordination, Phosphate bonding, Selectivity, Sorption isotherms, Sorption kinetics
in
Chemical Engineering Journal
volume
422
article number
130009
publisher
Elsevier
external identifiers
  • scopus:85105017825
ISSN
1385-8947
DOI
10.1016/j.cej.2021.130009
language
English
LU publication?
yes
id
55ec025b-2887-494a-9e2b-92798cb4155e
date added to LUP
2021-05-12 11:36:10
date last changed
2022-04-27 01:57:12
@article{55ec025b-2887-494a-9e2b-92798cb4155e,
  abstract     = {{<p>Phosphorus induced eutrophication of freshwaters is one of the great global challenges. As the critical threshold concentration for eutrophication is very low, there is a strong need for development of phosphate sorbents with high affinity and selectivity. Single sheet iron oxide (SSI), a nanomaterial prepared from oxidation and exfoliation of layered iron(II)-iron(III) hydroxide (green rust), is a fast reacting and promising sorbent. Phosphate sorption affinity and selectivity may be improved by incorporation of lanthanum (La) in the structure. Lanthanum was added during SSI synthesis resulting in La-SSIs with 0 to 22.5 wt% of La content. XPS and EXAFS showed all La was present as La(OH)<sub>3</sub> nanoclusters between iron hydroxide layers and on the surface of SSI. The sorbent showed fast phosphate sorption with 90% completion within 30 min and high stability with minimal La leaching. All La-SSI nanomaterials showed better sorption affinity than non-doped SSI, and the La-SSI with the highest La content showed an extreme affinity with K<sub>d</sub> of 10<sup>5</sup> L/kg at solution concentration of 0.1 mg P/L. The sorption affinity was not seriously affected by pH. The La-SSIs showed high selectivity for phosphate with&lt;10% reduction in phosphate sorption in presence of co-existing solutes (Cl<sup>–</sup>, NO<sub>3</sub><sup>–</sup>, SO<sub>4</sub><sup>2-</sup>, HCO<sub>3</sub><sup>–</sup> and humic acid). Similar high affinity and selectivity was seen for phosphate sorption in real natural waters. The main phosphate sorption mechanism is attributed to inner sphere Fe-O-P and La-O-P surface complexation. In conclusion La doping turns SSI into a high-affinity and selectivity sorbent that has potential for polishing low-phosphate yet eutrophying natural waters such as drainage and lake waters.</p>}},
  author       = {{Lu, Changyong and Klementiev, Konstantin and Hassenkam, Tue and Qian, Wenjie and Ai, Jing and Chr. Bruun Hansen, Hans}},
  issn         = {{1385-8947}},
  keywords     = {{Lanthanum coordination; Phosphate bonding; Selectivity; Sorption isotherms; Sorption kinetics}},
  language     = {{eng}},
  month        = {{10}},
  publisher    = {{Elsevier}},
  series       = {{Chemical Engineering Journal}},
  title        = {{High affinity lanthanum doped iron oxide nanosheets for phosphate removal}},
  url          = {{http://dx.doi.org/10.1016/j.cej.2021.130009}},
  doi          = {{10.1016/j.cej.2021.130009}},
  volume       = {{422}},
  year         = {{2021}},
}