Organic matter induced mobilization of polymer-coated silver nanoparticles from water-saturated sand

Transport of an Antibiotic Resistance Plasmid through Iron-Oxide-Coated Sand: Influence of the Anionic Hofmeister Effect and Coexisting Kaolinite Colloids

“…The Supporting Information (SI Figure S3) confirmed that such a reducing effect was stronger in Na 2 SO 4 (with a decreasing colloid BTC height from 25% to 15%) than in NaNO 3 (from 8% to 6%) and NaCl (from 7% to 5%). Other relevant work also demonstrated the role of polymer coatings in modulating the particle mobility. , (b) The clay colloids might be less effective in attaching and transporting the plasmid in Na 2 SO 4 than in the other two solutions due to the higher electrostatic repulsion between the plasmid and the clay colloids in Na 2 SO 4 , as confirmed by the zeta potential measurements.…”

“…Iron-oxide-coated sand was used as the column filling material. Quartz sand, with a grain size of 0.2∼0.3 mm, was coated with iron oxide using our established approach . Scanning electron microscopy (SEM) imaging suggests that this approach generated abundant submicrometer-sized clusters of iron oxides on the coated sand grain surfaces, which better represented the surface heterogeneity of natural sand (which usually bears oxide minerals) and functioned as favorable deposition sites for the negatively charged particles .…”

“…Quartz sand, with a grain size of 0.2∼0.3 mm, was coated with iron oxide using our established approach. 26 Scanning electron microscopy (SEM) imaging suggests that this approach generated abundant submicrometer-sized clusters of iron oxides on the coated sand grain surfaces, which better represented the surface heterogeneity of natural sand (which usually bears oxide minerals) and functioned as favorable deposition sites for the negatively charged particles. 26 The sand was sterilized with an autoclave prior to use.…”

Interplay of Natural Organic Matter with Flow Rate and Particle Size on Colloid Transport: Experimentation, Visualization, and Modeling

“…Deposition in the secondary well is a reversible process because a chemical perturbation reducing the well depth may release the retained particles. , Humic acid can convey electrosteric repulsion to the sand surface, resulting in an increasing barrier height and a decreasing well depth. ,, Consequently, the observed nanoparticle release may result from particles retained in the shallow secondary well, due to the NOM modification of the sand surface, as also suggested by other relevant studies using different organic polymers and nanomaterials. , Absence of significant microsphere release is speculated due to the comparatively insignificant steric effect of SRHA on the larger compared with the smaller particles. Other researchers have reported that, unless the polymer layer were sufficiently thick, it would not generate a significant steric effect on larger particles…”

“…29,38,39 Consequently, the observed nanoparticle release may result from particles retained in the shallow secondary well, due to the NOM modification of the sand surface, as also suggested by other relevant studies using different organic polymers and nanomaterials. 10,40 Absence of significant microsphere release is speculated due to the comparatively insignificant steric effect of SRHA on the larger compared with the smaller particles. Other researchers have reported that, unless the polymer layer were sufficiently thick, it would not generate a significant steric effect on larger particles.…”