title: Effects of pH and phosphate on CeO2 nanoparticle dissolution.
abstract: As the result of rapidly grown nanotechnology industries, release of engineered nanoparticles (ENPs) to environment has increased, posing in a serious risk to environmental and human health. To better understand the chemical fate of ENPs in aquatic environments, solubility of CeO2 NPs was investigated using batch dissolution experiments as a function of pH (1.65-12.5), [phosphate] and particle size (33 and 78 nm). It was found that CeO2 dissolution was only significant at pH<5 and inversely proportional to surface area. After 120 h, the release of Ce was ∼3 times greater in large NPs than that in small NPs that is likely contributed by the difference in exchangeable Ce(III) impurity (small: 0.3 mM kg(-1), large: 1.56 mM kg(-1)). When 100 μM of phosphate was added, the dissolution rate of CeO2 NPs was decreased in small NPs by 15% at pH 1.65 and 75% at pH 4.5 and in large NPs by 56% at pH 1.65 and 63% at pH 4.5. The inner-sphere surface complexation of P that is revealed by the zeta potential measurements is effectively suppressing the CeO2 NP dissolution. Predicting the fate and transport of CeO2 NPs in aquatic environment, pH and P ligands might play important roles in controlling the solubility of CeO2 NPs.
authors.affiliation: Clemson University, School of Agricultural, Forest and Environmental Sci., Clemson, SC 29634, USA.
authors.forename: Jessica T
authors.initials: JT
authors.lastname: Dahle
authors.affiliation: The Integrated Imaging Center/HRAEM Facility, Departments of Earth and Planetary Sci., Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Livi
authors.affiliation: Department of Natural Resources and Environmental Sci., University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. Electronic address: yarai@illinois.edu.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
mesh_terms: D000327:Adsorption; D002563:Cerium / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry*; D005583:Fourier Analysis; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D010710:Phosphates / Q000737:chemistry* / Q000494:pharmacology; D012995:Solubility / Q000187:drug effects; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D010710:Phosphates; D002563:Cerium; C030583:ceric oxide
keywords: CeO(2); Cerium nanoparticle; Cerium oxide; Dissolution; Nanoparticle; Phosphate sorption