title: Modeling the effects of surfactant, hardness, and natural organic matter on deposition and mobility of silver nanoparticles in saturated porous media.
abstract: This study aims to provide insights into the mechanisms governing the deposition and retention of silver nanoparticles (AgNPs) in saturated porous media. Column experiments were conducted with quartz sand under saturated conditions to investigate the deposition kinetics of AgNPs, their mobility at different groundwater hardnesses (10-400 mg/L as CaCO3), and humic acid (HA, 0-50 mg/L as dissolved organic carbon [DOC]). An anionic surfactant, sodium dodecyl sulfate (SDS), was used as a dispersing agent to prepare a SDS-AgNPs suspension. The deposition kinetics of AgNPs were highly sensitive to the surfactant concentration, ionic strength, and cation type in solution. The breakthrough curves (BTCs) of SDS-AgNPs suggested that the transport and retention were influenced by groundwater hardness and HA. At low water hardness and high HA, high mobility of SDS-AgNPs was observed in saturated conditions. However, the retention of SDS-AgNPs increased substantially in very hard water with a low concentration of HA, because of a decreased primary energy barrier and the straining effect during the course of transport experiments. A modified clean-bed filtration theory and a two-site kinetic attachment model showed good fits with the BTCs of SDS-AgNPs. The fitted model parameters (katt and kstr) could be used successfully to describe that the retention behaviors were dominated by electrostatic and electrosteric repulsion, based on extended Derjaguin-Landau-Vaerwey-Overbeek calculations.
authors.affiliation: Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, SC, 29208, USA.
authors.forename: Chang Min
authors.initials: CM
authors.lastname: Park
authors.affiliation: Department of Civil and Environmental Engineering, Korea Army Academy at Young-Cheon, 495 Hogook-ro, Kokyungmeon, Young-Cheon, Gyeongbuk, 38900, South Korea.
authors.forename: Jiyong
authors.initials: J
authors.lastname: Heo
authors.affiliation: Department of Civil and Environmental Engineering, Korea Army Academy at Young-Cheon, 495 Hogook-ro, Kokyungmeon, Young-Cheon, Gyeongbuk, 38900, South Korea.
authors.forename: Namguk
authors.initials: N
authors.lastname: Her
authors.affiliation: Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, SC, 29208, USA.
authors.forename: Kyoung Hoon
authors.initials: KH
authors.lastname: Chu
authors.affiliation: Department of Environmental Engineering, Kwangwoon University, 447-1 Wolgye-Dong, Nowon-Gu, Seoul, South Korea.
authors.forename: Min
authors.initials: M
authors.lastname: Jang
authors.affiliation: Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, SC, 29208, USA. Electronic address: yoony@cec.sc.edu.
authors.forename: Yeomin
authors.initials: Y
authors.lastname: Yoon
mesh_terms: D006244:Hardness; D053758:Nanoparticles; D016062:Porosity; D012822:Silicon Dioxide; D012834:Silver; D013501:Surface-Active Agents
chemical_list: D013501:Surface-Active Agents; D012834:Silver; D012822:Silicon Dioxide
keywords: Collision; Hardness; Humic acid; Retention; Silver nanoparticle; Transport