in situ methods for monitoring silver nanoparticle sulfidation in simulated waters

Published

September 16, 2016

Author(s)

John M. Pettibone, Jingyu Liu

Abstract

To probe the transformation pathways of metallic nanomaterials, measurement tools capable of detecting and characterizing the broad distribution of products with limited perturbation is ideal. Thus, we employed a suite of in situ measurements (single particle inductively coupled plasma mass spectrometry, SP-ICP-MS, hyphenated asymmetric flow field flow fractionation, A4F, and X-ray scattering measurements) to examine the transformations of extensively studied, commercially available 40 kDa PVP-coated silver nanoparticles (AgNPs) in aerated, sulfide-containing media. The corrosion of two AgNP sizes, 40 nm and 75 nm, were examined as function of increasing sulfide to Ag ratios, excess natural organic matter (fulvic acid, FA), pH, NP concentration and different simulated environmental media (surface and moderately hard reconstituted water). In contrast to previous reports of citrate or PVP-capped AgNP sulfidation that resulted in extensive aggregation, the total Ag mass was preserved in the primary NPs during corrosion under nearly all conditions examined. However, the information gleaned from the combined measurements was necessary to capture a more complete picture of the contributing factors to transformation that were systematically evaluated. SP-ICP-MS demonstrated the mass retainment in the primary NP population based on mass distribution and number concentration in both the absence and presence of FA. Validated hyphenated A4F techniques probe a broader mass distribution, including the NP sizes that are below the SP-ICP-MS detection limit, and exhibited a population of small Ag species that persisted in corrosive environments. The contribution from sub-5 nm species has not been well characterized due to difficulties inherent in commonly used measurement techniques, but a preponderance of evidence for their formation and persistence is developing. SAXS measurements corroborated their presence and persistence with high size resolution.

Citation

Environmental Science and Technology

Pub Type

Journals

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DOI Link

Keywords

Nanoparticles, transformation, in situ measurements, NanoEHS, sulfidation, field flow fractionation, ICP-MS

Citation

Pettibone, J. and Liu, J. (2016), in situ methods for monitoring silver nanoparticle sulfidation in simulated waters, Environmental Science and Technology, [online], https://doi.org/10.1021/acs.est.6b03023 (Accessed April 23, 2024)