Mobility of capped silver nanoparticles under environmentally relevant conditions

Area of Science:

• Environmental Science
• Nanotechnology
• Surface Chemistry

Background:

• Silver nanoparticles (Ag NPs) are increasingly used, raising concerns about their environmental fate.
• Understanding nanoparticle behavior in aquatic systems is crucial for risk assessment.

Purpose of the Study:

• To investigate the mobility and deposition of capped Ag NPs on silica surfaces.
• To evaluate the influence of pH, ionic strength, and capping agents on Ag NP behavior.

Main Methods:

• Characterization of Ag NP and silica surface charge across various pH and ionic strength conditions.
• Assessment of deposition rates in different water matrices (seawater, freshwater).
• Evaluation of capping agents (citrate, PVP) and natural organic matter effects.

Main Results:

• Capped Ag NPs and silica surfaces were predominantly negatively charged, leading to electrostatic repulsion.
• Steric repulsion from capping agents significantly reduced aggregation and deposition.
• Natural organic matter further decreased Ag NP deposition on silica.
• Ag NPs exhibited high mobility with minimal deposition under tested environmental conditions.

Conclusions:

• Capped Ag NPs are highly mobile in aquatic environments, with limited deposition on silica.
• Capping agents and natural organic matter play key roles in mitigating Ag NP deposition.
• Findings are critical for assessing the environmental risks of silver nanoparticles.