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Silver speciation and release in commercial antimicrobial textiles as influenced by washing
Citation:
Lombi, E., E. Donner, K. Scheckel, R. Sekine, C. Lorenz, N. Von Goetz, AND B. Nowack. Silver speciation and release in commercial antimicrobial textiles as influenced by washing. J. de Boer and S.A. Snyder (ed.), CHEMOSPHERE. Elsevier Science Ltd, New York, NY, 111:352-358, (2014).
Impact/Purpose:
Reliable information regarding Ag speciation and release during washing is essential knowledge required to decrease the uncertainties related to environmental exposure assessment of nanomaterials. Models that are being developed to predict environmental concentrations of NPs (Gottschalk et al., 2010, 2013) rely on information regarding input parameters as well as release rates, which are controlled by various factors including speciation. In this study, we aimed to significantly expand the knowledge base regarding Ag speciation in commercial textiles by undertaking XANES analysis of 5 commercial textile products. Clearly this knowledge is also relevant in the context of consumer information as manufacturers often provide limited information on their labels and these may not necessarily be correct. Furthermore, the release of Ag from textiles during two different washing procedures was investigated. Finally, the speciation of the washed textiles was also investigated as this provides information regarding the potential for further release from successive washings.
Description:
The use of nanoscale Ag in textiles is one the most often mentioned uses of nano-Ag. It has previously been shown that significant amounts of the Ag in the textiles are released upon washing. However, the form of Ag present in the textiles remains largely unknown as product labelling is insufficient. The aim of this study was therefore to investigate the solid phase speciation of Ag in original and washed silver textile using XANES. The original Ag speciation in the textiles was found to vary greatly between different materials with Ag(0), AgCl, Ag2S, Ag-phosphate, ionic Ag and other species identified. Furthermore, within the same textile a number of different species were found to coexist. This is likely due to a combination of factors such as the synthesis processes at industrial scale and the possible reaction of Ag with atmospheric gases. Washing with two different detergents resulted in marked changes in Ag-speciation. For some textiles the two detergents induced similar transformation, in other textiles they resulted in very different Ag species. This study demonstrates that in functional Ag textiles a variety of different Ag species coexist before and after washing. These results have important implications for the risk assessment of Ag textiles because they show that the metallic Ag is only one of the many silver species that need to be considered.
