High retention of silver sulfide nanoparticles in natural soils

Min Li; Ben K Greenfield; Luis M Nunes; Fei Dang; Hai-Long Liu; Dong-Mei Zhou; Bin Yin

doi:10.1016/j.jhazmat.2019.06.012

High retention of silver sulfide nanoparticles in natural soils

J Hazard Mater. 2019 Oct 15:378:120735. doi: 10.1016/j.jhazmat.2019.06.012. Epub 2019 Jun 5.

Authors

Min Li¹, Ben K Greenfield², Luis M Nunes³, Fei Dang⁴, Hai-Long Liu¹, Dong-Mei Zhou⁵, Bin Yin⁶

Affiliations

¹ Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
² Department of Environmental Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA.
³ University of Algarve, Civil Engineering Research and Innovation for Sustainability Center, Faro, Portugal.
⁴ Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China. Electronic address: fdang@issas.ac.cn.
⁵ Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
⁶ State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China. Electronic address: byin@issas.ac.cn.

PMID: 31203124
DOI: 10.1016/j.jhazmat.2019.06.012

Abstract

Silver, either in ionic or nanoparticulate form, is widely used in consumer products. However, silver sulfide (Ag₂S) are more likely to be the form that Ag enters the environment. The retention of silver sulfide nanoparticles (Ag₂S-NPs) in natural soils is critical for bioavailability and toxicity but remains unclear. Here, we examined the retention of Ag₂S-NPs in 11 natural soils with varying properties using batch assays. More than 99% of Ag₂S-NPs were retained in soil solids, irrespective of soil properties. Such high retention of Ag₂S-NPs, at least partially, explained the distinct differences in phytoavailability performed in soil vs. liquid media in the literature. Nanoparticles containing Ag and S were identified in representative soil solids by high resolution transmission electron microscopy equipped with an energy dispersive X-ray spectrometer. Iron-rich acidic soil had a high dissolution of Ag₂S-NPs ranging from 47.1% to 61.7% in porewater. In contrast to Ag₂S-NPs, silver nanoparticles (AgNPs) and Ag⁺ in these soils were less retained (as described by Freundlich model) and the retention was closely associated with soil properties. These findings highlight the unique behaviors of Ag₂S-NPs in natural soils.

Keywords: Retention; Silver speciation; Silver sulfide nanoparticles; Soil property; Transformation.

Publication types

Research Support, Non-U.S. Gov't