A Study of Silica Nanoparticle Adsorption Using Optical Reflectometry and Streaming Potential Techniques

Abstract

The kinetics of adsorption of monodisperse nanosized silica particles (32−190 nm diameter) on silicon wafers modified with an aminopropylsilane have been studied by optical reflectometry under stagnant-flow conditions. The adsorption of negatively charged particles on a positively charged wafer surface is driven by electrical double layer attraction and was not found to be measurably reversible. The initial rate of particle adsorption decreases with increasing particle size while the equilibrium amount adsorbed increases with electrolyte concentration. The effect of particle adsorption on the ζ potential of similarly modified glass slides was measured using streaming potential apparatus. The coverage of particles was varied using electrolyte as indicated by the reflectometry measurements. The results suggest that displacement of the plane of shear is not localized to particle covered areas.

Deposition of silica nanoparticles onto alumina measured by optical reflectometry and quartz crystal microbalance with dissipation techniques

“…The initial deposition rate increased with decreasing particle size and increasing particle concentration [19,20]. They also showed that while the deposited amount of nanoparticles and surface coverage increased with increasing concentration of NaCl, the initial deposition rate remained unaffected [19,20].…”

“…The deposition of nanoparticles can also be studied by optical reflectometry (OR) [16,[18][19][20][21] where the reflecting substrate carries a thin dielectric layer [22]. Böhmer et al used OR to study how the size and concentration of silica nanoparticles and the ionic strength affected the deposition onto polyelectrolyte-coated substrates [19][20][21].…”

“…Böhmer et al used OR to study how the size and concentration of silica nanoparticles and the ionic strength affected the deposition onto polyelectrolyte-coated substrates [19][20][21]. The initial deposition rate increased with decreasing particle size and increasing particle concentration [19,20].…”

“…Böhmer et al used OR to study how the size and concentration of silica nanoparticles and the ionic strength affected the deposition onto polyelectrolyte-coated substrates [19][20][21]. The initial deposition rate increased with decreasing particle size and increasing particle concentration [19,20]. They also showed that while the deposited amount of nanoparticles and surface coverage increased with increasing concentration of NaCl, the initial deposition rate remained unaffected [19,20].…”

Three-Dimensional Structure of Electroosmotic Flow over Heterogeneous Surfaces

“…15,16 In this technique the surface's electrokinetic properties are altered by introducing a heterogeneous region, for example due to protein adsorption, which has a different -potential than the original surface. The introduction of this heterogeneous region induces a change in the surface's average -potential, which is monitored via a streaming potential measurement, and related back to the degree of surface coverage.…”