title: Effect of Size-Selective Retention on the Cotransport of Hydroxyapatite and Goethite Nanoparticles in Saturated Porous Media.
abstract: Attributable to their nanoscale size and slow phosphorus (P) release kinetics, hydroxyapatite nanoparticles (HANPs) are increasingly advocated as a promising P nanofertilizer. Additionally, HANPs have been extensively used to remediate soils, groundwater, and nuclear wastewaters contaminated with metals and radionuclides. Increasing application of HANPs for agronomic and environmental advantages will expedite their dissemination in subsurface environments. Because the biogeochemical cycling of P is intimately coupled with iron, it is anticipated that HANPs and released P from HANPs interact with iron oxides, particularly naturally occurring goethite nanoparticles (GNPs) because of their nanoscale size and high reactivity toward P. Here, we investigated the cotransport and retention of HANPs and GNPs in water-saturated sand columns under environmentally relevant transport conditions (pH and natural organic matter type and concentration). Our results indicated that the "size-selective retention", i.e., preferential retention of larger particles near the column inlet and elution of smaller particles occurred during cotransport of HANPs and GNPs, and the cotransport of both NPs is highly sensitive to solution chemistry that determines NPs dissolution, homo- and heteroaggregation, and co- and competitive-retention. These findings have important insights into application of HANPs as a promising P nanofertilizer and an in situ amendment for contaminated site remediation.
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Dengjun
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Yan
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Deb P
authors.initials: DP
authors.lastname: Jaisi
mesh_terms: D017886:Durapatite / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D005308:Fertilizers; D060587:Groundwater; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry*; D007700:Kinetics; D008903:Minerals / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry; D016062:Porosity; D012822:Silicon Dioxide; D012987:Soil
chemical_list: D005290:Ferric Compounds; D005308:Fertilizers; D058085:Iron Compounds; D008903:Minerals; D012987:Soil; C094886:goethite; C000499:ferric oxide; D010758:Phosphorus; D012822:Silicon Dioxide; D017886:Durapatite; D007501:Iron