Ionic-strength-dependent effect of suspended sediment on the aggregation, dissolution and settling of silver nanoparticles.

Jian Zhao, Yang Li, Xinjie Wang, Xinghui Xia, Enxiang Shang, Jawad Ali

Environmental pollution (Barking, Essex : 1987) 2021 Jun 15

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Suspended sediment (SS) is ubiquitous in natural waters and plays a key role in the fate of engineered nanomaterials. In this study, the effect of SS on the aggregation, settling, and dissolution of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) was investigated under environmentally relevant conditions. The heteroaggregation of AgNPs with SS was not observed at low ionic strength (≤0.01 M) due to high electrostatic repulsion and steric forces. At higher NaCl concentrations (0.1 and 0.3 M), PVP-AgNPs were found to attach onto the SS surface, and the formation of AgNP-SS heteroaggregates strongly promoted settling of PVP-AgNPs due to the overwhelming gravity force. PVP-AgNP dissolution was reduced after the addition of sediment to ultrapure water because the presence of sediment-associated dissolved organic matter (SS-DOM). The formation of an AgCl layer on PVP-AgNP surface in 0.01 M NaCl solution resulted in the minor effect of SS on AgNP dissolution. After addition of SS, the dissolved silver concentrations of PVP-AgNP increased in 0.1 and 0.3 M NaCl solution. The interactions of SS-DOM with AgNPs under different NaCl concentrations interfered the dissolution of AgNPs in sediment-laden water. This study provides new insight into the fate of AgNPs in sediment-laden water under various environmental conditions. Copyright © 2021 Elsevier Ltd. All rights reserved.

Citation

Jian Zhao, Yang Li, Xinjie Wang, Xinghui Xia, Enxiang Shang, Jawad Ali. Ionic-strength-dependent effect of suspended sediment on the aggregation, dissolution and settling of silver nanoparticles. Environmental pollution (Barking, Essex : 1987). 2021 Jun 15;279:116926