Due to the rise of nanotechnology in industry, the concentrations of engineered metal oxide nanoparticles being released to the environment are increasing daily. Popular applications of CeO2 nanoparticles are of concern because of the increasing demand in pharmaceutical (antiemetic and antithrombic drugs) and industries (mischmetal for metallurgical purposes, abrasives). To understand the chemical interactions of CeO2 nanoparticles post-environmental release (e.g., water treatment plants), the dissolution of small (10 � 30 nm) and large (50 � 105 nm) manufactured CeO2 NPs was studied as a function of pH and ionic strength in the absence and presence of organic ligands (e.g., acetate, fulvic acid). In the absence of organic ligands, it was found that the dissolution of CeO2 nanoparticles was negligible at pH > 7 and was only significant at pH < 5. The rate constant in small NPs decreased from 0.045 to 0.025 mM Ce/CeO2 kg�hr. with increasing pH 1.65 and 4.45. Similarly, the rate constant in large NPs decreased from 0.061 to 0.022 mM Ce/CeO2 kg�hr when pH was increased from 1.65 to 4.45. When >100 �M organic acids (e.g., acetate) was present, dissolution of CeO2 NPs was enhanced at pH <5. While the organic ligands might play an important role in controlling the Ce release from CeO2 NPs, it was also postulated that Ce(III) impurity could contribute the initial dissolution process. Overall dissolution mechanisms and processes will be discussed via the results of kinetic models and physicochemical characterization of CeO2 nanoparticles.

Influence of pH, organic ligands, ionic strength on dissolution kinetics of CeO<sub>2</sub> nanoparticles

246th National Meeting (2013)

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Influence of pH, organic ligands, ionic strength on dissolution kinetics of CeO2 nanoparticles

Influence of pH, organic ligands, ionic strength on dissolution kinetics of CeO₂ nanoparticles