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.

Metal‐based nanoparticles in soil: Fate, behavior, and effects on soil invertebrates

“…Conversely, Al 2 O 3 NPs (50 nm) with adsorbed phosphate, producing a net negative charge, showed reduced sorption to soil and hence higher mobility [73]. A similar effect of phosphate on CeO 2 NPs has also been noted [56]. The ionic strength of the soil solution also influences the tendency of particles to sorb to the soil.…”

“…Approximately 10 to 17% of Ag NPs (30-50 nm) were found to be transformed to Ag(I) after 28 d, suggesting oxidative dissolution to ions [55]. The dissolution of CeO 2 NPs has been shown to be very low in different types of soil [56]. The dissolution (or dispersion) of Ag and CeO 2 NPs has been shown to vary with soil composition [57].…”

Environmental Stresses Increase Photosynthetic Disruption by Metal Oxide Nanomaterials in a Soil-Grown Plant

“…TiO 2 is known to be highly insoluble in water and CeO 2 is similarly insoluble at pHs similar to those found in the potting soil used here (5.7). 60 Additionally, both ENMs have been found to be taken up into a variety of plant species in nanoparticulate form. 4,42,52,61 However, the Cu(OH) 2 ENM used here is known to undergo partial dissolution under acidic conditions 30,31 and will likely be at least partially present either as ionic Cu 1þ /Cu 2þ or as part of a complex with ions from the surrounding media.…”

Environmental release, fate and ecotoxicological effects of manufactured ceria nanomaterials

“…64 Contrary to some other manufactured nanoparticles (such as Ag, ZnO, CuO), nanoceria have an inherently low solubility. Negligible solubility was reported; e.g.…”