title: Influence of natural organic matter on transport and retention of polymer coated silver nanoparticles in porous media.
abstract: Interactions between organic matter (OM) and engineered polymer coatings as they affect the retention of polyvinylpyrrolidone (PVP) polymer-coated silver nanoparticles (AgNPs) were studied. Two distinct types of OM-cysteine representing low molecular weight multivalent functional groups, and Suwannee River Humic Acid (HA) representing high molecular weight polymers, were investigated with respect to their effects on particle stability in aggregation and deposition. Aggregation of the PVP coated AgNPs (PVP-AgNPs) was enhanced by cysteine addition at high ionic strengths, which was attributed to cysteine binding to the AgNPs and replacing the otherwise steric stabilizing agent PVP. In contrast the addition of HA did not increase aggregation rates and decreased PVP-AgNP deposition to the silica porous medium, consistent with enhanced electrosteric stabilization by the HA. Although cysteine also reduced deposition in the porous medium, the mechanisms of reduced deposition appear to be enhanced electric double layer (EDL) interaction at low ionic strengths. At higher ionic strengths, aggregation was favored leading to lower deposition due to smaller diffusion coefficients and single collector efficiencies despite the reduced EDL interactions.
authors.affiliation: Provincial Key Laboratory of Agricultural Environmental Engineering, College of Resources and Environment, Sichuan Agricultural University, No. 211, Huiming Road, Chengdu 611130, Sichuan, China; Department of Civil and Environmental Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, United States; Center for Environmental Implications of NanoTechnology (CEINT), Duke University, Durham, NC 27708, United States; Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences (CAS), Nanjing 210008, Jiangsu, China. Electronic address: yangxinyao@hotmail.com.
authors.forename: Xinyao
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Civil and Environmental Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, United States; Center for Environmental Implications of NanoTechnology (CEINT), Duke University, Durham, NC 27708, United States.
authors.forename: Shihong
authors.initials: S
authors.lastname: Lin
authors.affiliation: Department of Civil and Environmental Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, United States; Center for Environmental Implications of NanoTechnology (CEINT), Duke University, Durham, NC 27708, United States. Electronic address: wiesner@duke.edu.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wiesner
mesh_terms: D003102:Colloids; D004586:Electrophoresis; D007700:Kinetics; D053758:Nanoparticles / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D011205:Povidone; D012834:Silver / Q000737:chemistry*
chemical_list: D003102:Colloids; D009930:Organic Chemicals; D012834:Silver; D011205:Povidone
keywords: Cysteine; Differential organic matter effect; Humic acid; PVP coated silver nanoparticle; Transport in porous medium