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    Interactions between surfactants and silver nanoparticles of varying charge

    Year: 2012

    Journal: Journal of Colloid and Interface Science, Volume 369, Issue 1, 1 March 2012, Pages 193–201, 20120618

    Authors: J. Hedberg a, M. Lundin a, b, T. Lowe a, b, E. Blomberg a, c, S. Wold b, I. Odnevall Wallinder a

    Last authors: I. Odnevall Wallinder

    Organizations: •a KTH Royal Institute of Technology, School of Chemical Science and Technology, Surface and Corrosion Science, SE-100 44 Stockholm, Sweden •b KTH Royal Institute of Technology, School of Chemical Science and Technology, Applied Physical Chemistry, SE-100 44 Stockholm, Sweden •c Institute for Surface Chemistry, P.O. Box 5607, SE-114 86 Stockholm, Sweden

    Country: Sverige, Sweden

    The interaction between silver nanoparticles (Ag NPs) of different surface charge and surfactants relevant to the laundry cycle has been investigated to understand changes in speciation, both in and during transport from the washing machine. Ag NPs were synthesized to exhibit either a positive or a negative surface charge in solution conditions relevant for the laundry cycle (pH 10 and pH 7). These particles were characterized in terms of size and surface charge and compared to commercially laser ablated Ag NPs. The surfactants included anionic sodium dodecylbenzenesulfonate (LAS), cationic dodecyltrimethylammoniumchloride (DTAC) and nonionic Berol 266 (Berol). Surfactant–Ag NP interactions were studied by means of dynamic light scattering, Raman spectroscopy, zeta potential, and Quartz Crystal Microbalance. Mixed bilayers of CTAB and LAS were formed through a co-operative adsorption process on positively charged Ag NPs with pre-adsorbed CTAB, resulting in charge reversal from positive to negative zeta potentials. Adsorption of DTAC on negatively charged synthesized Ag NPs and negatively charged commercial Ag NPs resulted in bilayer formation and charge reversal. Weak interactions were observed for nonionic Berol with all Ag NPs via hydrophobic interactions, which resulted in decreased zeta potentials for Berol concentrations above its critical micelle concentration. Differences in particle size were essentially not affected by surfactant adsorption, as the surfactant layer thicknesses did not exceed more than a few nanometers. The surfactant interaction with the Ag NP surface was shown to be reversible, an observation of particular importance for hazard and environmental risk assessments.