Effects of pH and phosphate on CeO2 nanoparticle dissolution

Area of Science:

• Environmental Science
• Nanotechnology
• Materials Science

Background:

• Engineered nanoparticles (ENPs) are increasingly released into the environment.
• Understanding the environmental behavior of ENPs is crucial for risk assessment.
• Cerium oxide nanoparticles (CeO2 NPs) are widely used and their aquatic fate requires investigation.

Purpose of the Study:

• To investigate the solubility of CeO2 NPs in aquatic environments.
• To determine the influence of pH, phosphate concentration, and particle size on CeO2 NP dissolution.
• To predict the environmental fate and transport of CeO2 NPs.

Main Methods:

• Batch dissolution experiments were conducted.
• Solubility was measured as a function of pH (1.65-12.5), phosphate concentration, and particle size (33 nm and 78 nm).
• Zeta potential measurements were used to understand surface interactions.

Main Results:

• CeO2 NP dissolution was significant only at pH < 5 and inversely proportional to surface area.
• Larger NPs showed approximately 3 times greater Ce release than smaller NPs after 120 h.
• Phosphate addition significantly decreased CeO2 NP dissolution, especially at lower pH, due to inner-sphere surface complexation.

Conclusions:

• The solubility and dissolution of CeO2 NPs are strongly influenced by environmental factors.
• pH and phosphate ligands play critical roles in controlling CeO2 NP solubility in aquatic systems.
• These findings are important for predicting the environmental fate and transport of CeO2 NPs.