Aqueous Aggregation and Surface Deposition Processes of Engineered Superparamagnetic Iron Oxide Nanoparticles for Environmental Applications

Abstract

Engineered, superparamagnetic, iron oxide nanoparticles (IONPs) have significant potential as platform materials for environmental sensing, imaging and remediation due to their unique size, physicochemical and magnetic properties. To this end, controlling the size and surface chemistry of the materials is crucial for such applications in the aqueous phase, and in particular, for porous matrixes with particle-surface interaction considerations. In this study, superparamagnetic, highly monodispersed 8 nm IONPs were synthesized and transferred into water as stable suspensions (remaining monodispersed) by way of an interfacial oleic acid bilayer surface. Once stabilized and characterized, particle-particle and model surface interactions (deposition and release) were quantitatively investigated and described systematically as a function of ionic strength (IS) and type with time-resolved dynamic light scattering (DLS), zeta potential, and real-time quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. The critical coagulation concentration (CCC) for oleic acid bilayer coated iron oxide nanoparticles (OA-IONPs) were determined to be 710 mM for NaCl (matching DLVO predictions) and 10.6 mM for CaCl2, respectively. For all conditions tested, surface deposition kinetics showed stronger, more favorable interactions between OA-IONPs and polystyrene surfaces compared to silica, which is hypothesized to be due to increased particle-surface hydrophobic interactions (when compared to silica surfaces).

Deposition behavior of residual aluminum in drinking water distribution system: Effect of aluminum speciation

“…For Al 13 and Al 30 , with direct inspection, the slope of ΔD to Δf exhibited a linear relationship, which meant that no conformational alternation occurred during the deposition process (Che et al, 2014). With respect to Al o , the slope became larger with increasing | Δf | , which meant that the film became more loosely attached to the surface (Li et al, 2014).…”

“…The viscoelastic properties and conformational changes of the deposited layers could be evaluated by the ΔD-Δf plot, as shown in Fig.7a (Li et al, 2014). The slope of ΔD to Δf was steepest with Al o , followed by Al 30 and Al 13 , which indicated that the deposited layer of Al 13 was the most rigid and a most soft dissipative film was formed for Al o .…”

Self-Assembly of Magnetic Iron Oxide Nanoparticles Into Cuboidal Superstructures

“…Such strategies are used in oil-field rocks and contaminated geological systems. [7] Many technical applications are based on ferrofluids, which consist of magnetic nanoparticles in a non-magnetic solvent. Examples are damping devices or magnetic seals for rotating shafts.…”

QCM-D study of nanoparticle interactions

“…Meanwhile, the hydrophobicity of QCM-D sensor plays an important role in controlling the nanoparticle deposition. The deposition of OA-IONPs on polystyrene-coated sensor surfaces, on the other hand is stronger than on hydrophilic silica sensor surfaces as a result of increasing surface hydrophobicity as compared withunmodified silica sensor surfaces [136]. These results cannot be adequately described by the classic DLVO theory.…”