Characteristics and Mechanisms of Pb(II) Sorption onto Fe-rich waste Water Treatment Residue (WTR): A potential sustainable Pb immobilisation technology for soils

Findlay, Nina C.; Peacock, Caroline L.; Hudson-Edwards, Karen A.; Johnson, Karen L.

Abstract

Pb contamination of soils is a global problem. This paper discusses the ability of an Fe-rich waste, water treatment residual (WTR), to adsorb Pb(II). This was investigated using batch sorption experiments, X-ray diffraction, electron microprobe microanalysis, PHREEQC modelling and Extended X-ray Absorption Fine Structure (EXAFS) analysis. The WTR is composed of approximately 23 wt. % natural organic matter (NOM), 70 wt. % ferrihydrite and <10 wt. % silicate material. Pb(II) sorption to WTR was dependent on initial Pb(II) load, particle size, time and pH, but not on ionic strength. EXAFS analysis at the Pb LIII-edge confirmed that Pb(II) sorbed to WTR by co-existing bidentate edge-sharing and monodentate or corner-sharing complexes, with 2 O at ∼2.31–2.34 Å, 1 Fe at ∼3.32–3.34 Å, 2 Fe at ∼3.97–3.99 Å and 1 Pb at ∼3.82–3.85 Å. Linear combination showed that the Pb(II)-sorbed spectra were best fit with a ∼0.9 ± 0.1 and 0.1 ± 0.1 contribution from Pb(II)-sorbed ferrihydrite and Pb(II)-sorbed humic acid end members, respectively. Overall, we show that Pb(II) sorbs via strong inner-sphere complexation of Pb(II) to the ferrihydrite component of the WTR, which itself is stable over a wide pH range. Therefore, we suggest that Fe-rich WTR wastes could be used as effective adsorbents in Pb(II)-contaminated soils to help ensure sustainable terrestrial ecosystems.

Citation

Findlay, N. C., Peacock, C. L., Hudson-Edwards, K. A., & Johnson, K. L. (2021). Characteristics and Mechanisms of Pb(II) Sorption onto Fe-rich waste Water Treatment Residue (WTR): A potential sustainable Pb immobilisation technology for soils. Journal of Hazardous Materials, 402, Article 123433. https://doi.org/10.1016/j.jhazmat.2020.123433

• Journal Article Type: Article
• Acceptance Date: Jul 6, 2020
• Online Publication Date: Jul 8, 2020
• Publication Date: Jan 15, 2021
• Deposit Date: Jul 9, 2020
• Publicly Available Date: Jul 8, 2021
• Journal: Journal of Hazardous Materials
• Print ISSN: 0304-3894
• Electronic ISSN: 1873-3336
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 402
• Article Number: 123433
• DOI: https://doi.org/10.1016/j.jhazmat.2020.123433
• Public URL: https://durham-repository.worktribe.com/output/1266852