title: Agglomeration of Ag and TiO2 nanoparticles in surface and wastewater: Role of calcium ions and of organic carbon fractions.
abstract: This study aims to investigate factors leading to agglomeration of citrate coated silver (AgNP-Cit), polyvinylpyrrolidone coated AgNPPVP and titanium dioxide (TiO2) nanoparticles in surface waters and wastewater. ENPs (1 mg/L) were spiked to unfiltered, filtered, ultrafiltered (<10 kDa and <1 kDa) samples. Z-average particle sizes were measured after 1 h, 1 day and 1 week. AgNP-PVP was stable in all fractions of the samples and kept their original size around 60 nm over 1 week. Agglomeration of AgNP-Cit and TiO2 was positively correlated with Ca(2+) concentration, but dissolved organic carbon concentrations > 2 mg/L contributed to stabilizing these NP. Moreover, agglomeration of AgNP-Cit in the various organic matter fractions showed that high molecular weight organic compounds such as biopolymers provide stabilization in natural water. A generalized scheme for the agglomeration behavior of AgNP-Cit, AgNP-PVP and TiO2 in natural waters was proposed based on their relation with Ca(2+), Mg(2+) and DOC concentration.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf, Switzerland; Department of Environmental Engineering, Istanbul Technical University, Maslak, Istanbul, 34469, Turkey. Electronic address: topuze@itu.edu.tr.
authors.forename: Emel
authors.initials: E
authors.lastname: Topuz
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf, Switzerland. Electronic address: jacqueline.traber@eawag.ch.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Traber
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf, Switzerland. Electronic address: laura.sigg@eawag.ch.
authors.forename: Laura
authors.initials: L
authors.lastname: Sigg
authors.affiliation: Department of Environmental Engineering, Istanbul Technical University, Maslak, Istanbul, 34469, Turkey. Electronic address: talinli@itu.edu.tr.
authors.forename: Ilhan
authors.initials: I
authors.lastname: Talinli
mesh_terms: D002118:Calcium / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D019343:Citric Acid / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011205:Povidone / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry
chemical_list: D002118:Calcium; D002244:Carbon; D019343:Citric Acid; D011205:Povidone; D012834:Silver; D014025:Titanium; D062065:Wastewater; C009495:titanium dioxide
keywords: Agglomeration; Biopolymers; Molecular weight fractionation; Nanomaterials; Natural water