Stability and dissolution of silver nanoparticles in sediment-laden water: Influence of suspended sediment and associated dissolved organic matter

The released silver nanoparticles (AgNPs) will inevitably interact with suspended sediment (SS), because of the ubiquity and abundance of SS in aquatic systems. However, the effect mechanism of SS on the transformation of AgNPs remains unknown and unpredictable. This research investigated the effect of SS on the aggregation, settling, and dissolution of polyvinylpyrrolidone-coated (PVP) AgNPs under environmentally diverse salinity conditions. By determining the morphology of AgNP–SS heteroaggregates and using the DLVO analysis, we revealed that the heteroaggregation between AgNPs and SS was dependent on ionic strength. The formation of AgNP-SS heteroaggregates eventually lead to the rapid settling of AgNPs. Besides, the interactions of sediment-associated dissolved organic matter (SS-DOM) with AgNPs interfered the dissolution of AgNPs under different NaCl concentrations. The fate (i.e., aggregation, dissolution and settling) of AgNP in sediment-laden water has been found to be strongly dependent on the presence of SS, SS-DOM and ionic strength. This work provides novel insight into the interaction between suspended particulate matter and AgNPs as well as its effect on AgNP physicochemical transformation in aquatic environment.