Aggregation behaviour of engineered nanoparticles in natural waters: characterising aggregate structure using on-line...

Area of Science:

• Environmental Science
• Nanotechnology
• Water Chemistry

Background:

• Engineered nanoparticles (ENPs) behavior in aquatic environments is influenced by natural organic matter (NOM) adsorption, aggregation, and disaggregation.
• While ENP aggregation is studied, fewer investigations focus on the fate and disaggregation of ENP aggregates in natural waters.

Purpose of the Study:

• To develop and demonstrate a simple method for characterizing ENP aggregation behavior and aggregate structure in diverse natural waters.
• To investigate the relationship between environmental factors (DOM, ionic strength) and ENP aggregation and structure.

Main Methods:

• Characterization of ENP aggregation behavior and aggregate structure using a novel, simple method.
• Analysis of the influence of dissolved organic matter (DOM) concentration and ionic strength on ENP aggregation.
• Correlation of aggregate structure with adsorbed DOM and environmental conditions.

Main Results:

• ENP aggregate size and dissolved organic matter (DOM) adsorption capacity strongly correlate with DOM concentration and ionic strength (R(2)>0.97, p<.05).
• Aggregate structure is highly correlated with the amount of DOM adsorbed (R(2)>0.95, p<.05).
• High ionic strength leads to diffusion-governed aggregation, forming less stable, linear aggregates.
• Low ionic strength promotes compact aggregate structures via DOM binding and cation bridging, indicative of reaction-limited aggregation.

Conclusions:

• A straightforward method effectively characterizes ENP aggregation and structure in natural waters.
• DOM concentration and ionic strength are key determinants of ENP aggregate size, DOM adsorption, and structural characteristics.
• Aggregate structure is intrinsically linked to the extent of DOM adsorption and environmental conditions, influencing ENP fate in aquatic systems.