Transport of cerium oxide nanoparticles in saturated silica media: influences of operational parameters and aqueous chemical conditions

Abstract

This paper aimed to investigate the influences of operational parameters and aqueous chemical conditions on transport behaviors of cerium oxides nanoparticles (CeO2-NPs) in saturated silica media. Results indicated that increasing rates of attachment efficiency (α) were related with cationic types, and critical deposition concentration (CDC) for divalent cation (Ca2+ and Mg2+) were more than 31-fold of that for monovalent cation (Na+ and K+). Increase or reduction of electrolyte pH could both promote the mobility of CeO2-NPs in glass beads, while influence was more evident at alkaline conditions. α increased linearly with NPs concentrations, while decreased linearly with flow velocity in the column, and effects were related with electrolyte contents. Presence of surfactants could sharply decreased α, and SDS was more effective to facilitate CeO2-NPs transport than Triton X–100. With DOMs concentrations increasing, α firstly kept constant, then sharply declined, and finally reduced very slowly. The influence of DOMs on NPs deposition was in order of SA > HA > TA > BSA. Overall, this study revealed that aqueous chemical conditions was crucial to NPs transport in porous media, and would provide significant information for our understanding on the fate and transport of nanoparticles in natural environment.

Colloid Systems and Interfaces Stability of Cerium Oxide Nanoparticles in Aqueous Environments: Effects of pH, Ionic Composition, and Suwanee River Humic and Fulvic Acids

“…The strongly positively charged surface of CeO 2 NPs at pH < pH PZC resulted in the predominated role of electrostatic repulsion over attraction; thus the stability of CeO 2 NPs was enhanced. Similarly, due to the same mechanism above, the low pH enhanced the CeO 2 NP mobility, a result that is attributable to the increased stability of the CeO 2 NPs [40]. The similar influence of electrolyte on the stability of CeO 2 NPs was also noted in that the CeO 2 NPs were stable at low NaCl concentrations (<10 mM) and unstable at higher NaCl concentrations (>10 mM).…”

“…The transport of CeO 2 NPs in natural porous media (e.g., soil and aquifer systems) and in engineered porous media (e.g., sand filtration systems) was also the subject of study [35][36][37][38][39][40]. In terms of the physicochemical parameters, CeO 2 NP transport in saturated sand-packed columns was hindered in the presence of NaCl with high ionic strength (IS) values (larger than 10 mM) at pH 3 [37].…”

Delineating the Relationship between Nanoparticle Attachment Efficiency and Fluid Flow Velocity

“…Intuitively, attachment efficiency can be expected to be negligible (constant) or even decrease with increasing flow velocity as hydrodynamics can hinder attachment. ,,, Computationally, Bai and Tien proposed a predictive framework for attachment efficiency in terms of flow velocity. , In their model, the hydrodynamic torque (from lift and drag forces) releases the deposited particles, resulting in decreasing attachment efficiency. Supporting this, several previous studies yielded results that were consistent with Bai and Tien’s predictions of decreasing attachment efficiency with respect to the flow. − However, there have been a number of conflicting observations recently reported. ,− An empirical attachment efficiency model (correlating 80 data sets), developed by Phenrat et al, implies that the attachment efficiency increases as a function of the flow velocity, contrary to the model of Bai and Tien. , For the Phenrat empirical model, only NPs that were surface-encapsulated with organic coatings were considered. Based on this work, the role of organic coating material(s) seems significant but is not specifically delineated.…”

Coupled impact of proteins with different molecular weights and surface charges on TiO2 mobility

“…41 Protein was found to interact with NPs, which largely increased NP stability and transport through steric repulsive interaction, especially in high salt solutions. [42][43][44][45] In addition, the surface charge and molecular weight of proteins vary because of biogeochemical factors, which may lead to different interaction mechanisms with NPs. 29,46 Due to the complexity of the natural environment, there are many various types of proteins with different molecular weights and surface charges in natural water and soil systems.…”