The understanding of nanoparticle dissolution and behavior in aquatic environments is essential in environmental chemistry since it can directly affect the aquatic ecosystem and human health. Different parameters, such as nanoparticle size, aquatic pH and ionic strength among others, can affect the stability of nanoparticles in terms of dissolution and aggregation. Recently, MoO3 nanoparticles have shown photocatalytic properties under visible light making them capable of degrading water contaminants. In this study, we investigate the physiochemical properties and pH-dependency of MoO3 nanoparticles with different sizes and morphologies (nanorods, nanowires, and nanosheets). Furthermore, we examine the aggregation behavior of the MoO3 nanoparticles in the presence of monovalent or divalent salt solutions and the applicability of Derjaguin, Landau-Verwey-Overbeek (DLVO) theory in predicting the range of critical coagulation concentrations for these nanoparticles (CCC). The solubility at different pH values showed that at basic pH, the dissolution of the nanoparticles is higher than at acidic pH. We have also shown that depending on the pH, the production of reactive oxygen species can vary. Additionally, the aggregation rates can vary drastically depending on the nanoparticle size and structure. The presence of natural organic matter as well as changes in pH can have different effects on particle stability depending on the particle’s morphology. While CCC values between the different structures are similar, size and morphology dependent differences can be observed. Furthermore, we observed a weak trend between the solubility of the nanoparticles and resulting CCC. Despite the complexity of nanoparticle dissolution and kinetic behavior in water, we found that DLVO theory can be used to approximate the CCCs for the different salt solutions allowing us to predict particle behavior in a variety of water chemistries.

Changes in the physiochemical properties of MoO3 nanoparticles in aquatic systems

2019 Fall National Meeting

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