As a result of their unique size-dependent physical and chemical properties and their broad-spectrum toxicity to organisms, silver nanoparticles (AgNPs) have received an increased attention in the past decade. The environmental release of AgNPs is of concern and thus, it is of fundamental importance to investigate their fate and transport. This research examines the mobility of selected uncoated AgNPs as well as AgNPs coated with different capping agents in quartz sand (QS), ferrihydride coated sand (FcS) and kaolin coated sand (KcS). These AgNPs are 1) electrostatically stabilized (uncoated H2-AgNP and citrate coated AgNPs (Citrate-AgNPs)), 2) Sterically stabilized (Polyvinylpyrrolidone coated AgNPs (PVP-AgNPs)) and 3) electrostatically stabilized (branched polyethyleneimine coated AgNPs (BPEI-AgNPs)). The impact of natural organic matter (NOM) on the mobility of the selected AgNPs was also examined. The results show that physicochemical interactions were the dominant filtration mechanisms for the AgNPs in all porous media investigated except for the electrostatically stabilized AgNPs in KcS media where straining was the major deposition mechanism. The electrostatically stabilized AgNPs (H2-AgNPs and Citrate-AgNPs) exhibited higher deposition in KcS as compared to FcS media and were readily mobile in QS. The sterically stabilized PVP-AgNPs followed the same deposition order as the electrostatically stabilized AgNPs. Minimal deposition was exhibited by the electrosterically stabilized BPEI-AgNPs regardless of the porous media investigated. The presence of humic acid enhanced the mobility of all investigated AgNPs regardless of the stabilization mechanism (resulted from the capping agent) or soil reactivity.

Transport of silver nanoparticles in porous media: Surface chemistry, porous media reactivity and natural organic matter as key factors controlling mobility

243rd National Meeting (2012)

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