title: Solubility and batch retention of CeO2 nanoparticles in soils.
abstract: There is a paucity of information on the environmental fate of cerium oxide nanoparticles (CeO2 NPs) for terrestrial systems that may be exposed to CeO2 NPs by the application of biosolids derived from wastewater treatment systems. Using ultrafiltration (UF), dissolution, and nonequilibrium retention (Kr) values of citrate-coated (8 nm diameter) CeO2 NPs and partitioning (Kd) values of dissolved Ce(III) and Ce(IV) were obtained in suspensions of 16 soils with a diversity of physicochemical properties. Dissolution of CeO2 NPs studied in solutions was only significant at pH 4 and was less than 3.1%, whereas no dissolved Ce was detected in soils spiked with CeO2 NPs. Kr values of CeO2 NP were low (median Kr=9.6 L kg(-1)) relative to Kd values of dissolved CeIII and CeIV (median Kd=3763 and 1808 L kg(-1), respectively), suggesting low CeO2 NP retention in soils. Surface adsorption of phosphate to CeO2 NP caused a negative zeta potential, which may explain the negative correlation of log Kr values with dissolved phosphate concentrations and the significant reduction of Kr values upon addition of phosphate to soils. The positive correlation of Kr values with clay content suggested heterocoagulation of CeO2 NPs with natural colloids in soils. Co-addition of CeO2 NPs with biosolids, on the other hand, did not affect retention.
authors.affiliation: School of Agriculture, Food and Wine, University of Adelaide, SA 5005 Adelaide, Australia. geert.cornelis@adelaide.edu.au
authors.forename: Geert
authors.initials: G
authors.lastname: Cornelis
authors.forename: Brooke
authors.initials: B
authors.lastname: Ryan
authors.forename: Mike J
authors.initials: MJ
authors.lastname: McLaughlin
authors.forename: Jason K
authors.initials: JK
authors.lastname: Kirby
authors.forename: Douglas
authors.initials: D
authors.lastname: Beak
authors.forename: David
authors.initials: D
authors.lastname: Chittleborough
mesh_terms: D002563:Cerium / Q000032:analysis / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry; D053768:Metal Nanoparticles / Q000032:analysis / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*; D012995:Solubility; D014865:Waste Disposal, Fluid
chemical_list: D010710:Phosphates; D012987:Soil; D012989:Soil Pollutants; D019343:Citric Acid; D002563:Cerium; C030583:ceric oxide