Deposition of silver nanoparticles from suspensions containing tannic acid

• Deposition kinetics of silver nanoparticles in the presence of tannin was evaluated.
• Influence of organic contaminants on silver particle deposition was confirmed.
• The results enable to improve the biocidal activity of silver particles.

Deposition of charge-stabilized silver nanoparticles, from suspensions containing tannic acid (tannin), on mica covered by the poly(allylamine hydrochloride) (PAH) supporting layer was studied. Initially, the size distribution, stability and electrokinetic properties of the silver particles were determined using transmission electron microscopy (TEM), dynamic light scattering method (DLS) and microelectrophoretic measurements. Analogously, the physicochemical properties of tannin were thoroughly determined, especially its electrokinetic charge and the adsorption isotherm at PAH-covered mica substrate. Afterwards, the kinetics of silver particle deposition in the presence of controlled quantities of tannin was measured at ionic strength of 10−2 M. An abrupt decrease in the maximum coverage of silver particle monolayers was observed from 0.28 (in the absence of tannin) to 0.03 for 50 mg L−1 at 3 × 10−5 M of tannin in the suspension. These results were interpreted using the random sequential adsorption model (RSA), according to the competitive adsorption of tannin. Obtained results confirmed crucial influence of trace amounts of organic contaminants on the deposition of silver nanoparticles at solid substrates. Besides significance for basic science, this finding has practical consequences enabling to improve the biocidal activity of silver nanoparticles.

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