Impact of green synthesized iron oxide nanoparticles on the distribution and transformation of As species in contaminated soil

• Published in: Environmental pollution (1987) Vol. 258; p. 113668
• Main Authors: Su, Binglin, Lin, Jiajiang, Owens, Gary, Chen, Zuliang
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-03-2020
• Subjects: Arsenic; As speciation; Environmental Pollution; Ferric Compounds - chemistry; Green Chemistry Technology; Green synthesis; Iron oxide nanoparticles; Nanoparticles; Soil; Soil Pollutants; Soil stabilization; Soil stabilization; Green synthesis; Iron oxide nanoparticles; As speciation
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2019.113668

Iron nanoparticles (Fe NPs) have often been used for in situ remediation of both groundwater and soil. However, the impact of Fe NPs on the distribution and transformation of As species in contaminated soil is still largely unknown. In this study, green iron oxide nanoparticles synthesized using a euphorbia cochinchinensis leaf extract (GION) were used to stabilize As in a contaminated soil. GION exhibited excellent As stabilization effects, where As in non-specifically-bound and specifically-bound fractions decreased by 27.1% and 67.3% after 120 days incubation. While both arsenate (As (V)) and arsenite (As (III)) decreased after GION application, As (V) remained the dominant species in soil. X-ray photoelectron spectroscopy (XPS) confirmed that As (V) was the dominant species in specifically-bound fractions, while As (III) was the dominant species in amorphous and poorly-crystalline hydrous oxides of Fe and Al. Correlation analysis showed that while highly available As fractions were negatively correlated to oxalate and DCB extractable Fe, they were positively correlated to Fe2+ content, which indicated that Fe cycling was the main process influencing changes in As availability. X-ray fluorescence (XRF) spectroscopy also showed that the Fe2O3 content increased by 47.9% following GION soil treatments. Overall, this work indicated that As would be transformed to more stable fractions during the cycling of Fe following GION application and that the application of GION, even in small doses, provides a low-cost and ecofriendly method for the stabilization of As in soil.
XPS spectra of As and Fe with GION (a, c) and without GION (b, d) in the specifically-bound fraction (F2) and As and Fe with GION (e, g) and without GION (f, h) in the amorphous and poorly-crystalline hydrous oxides of Fe and Al fraction (F3). [Display omitted]
•GION was used to immobile As in the contaminated soil.•Arsenate (As (V)) and arsenite (As (III)) decreased after GION used.•As (V) was the dominant species in soil was observed.•As (III) dominated in amorphous and poorly-crystalline.
When added to an As contaminated soil green synthesized iron nanoparticles changed the distribution of As species and increased their transformation to more immobile fractions.