Reversible Adsorption Kinetics of Near Surface Dimer Colloids

Abstract

We investigate the effect of shape on reversible adsorption kinetics using colloidal polystyrene dimers near a solid glass surface as a model system. The interaction between colloid and wall is tuned using electrostatic, depletion, and gravity forces to produce a double well potential. The dwell times in each of the potential wells is measured from long duration particle trajectories. The height of each monomer relative to the glass surface is measured to a resolution of <20 nm by in-line holographic microscopy. The measured transition probability distributions are used in kinetic equations to describe the flux of particles to and from the surface. The dimers are compared to independent isolated monomers to determine the effects of shape on adsorption equilibria and kinetics. To elucidate these differences, we consider both mass and surface coverage and two definitions of surface coverage. The results show that dimers with single coverage produce slower adsorption and lower surface coverage in comparison to monomers while dimers with double coverage adsorb faster and result in higher surface coverage.

Heterogeneous Rate Constant for Amorphous Silica Nanoparticle Adsorption on Phospholipid Monolayers

“…In this study, any change in the size of the particle has no significant effect on the activation step, unlike in other studies, 60 and the promotion of the interaction with the lipid layer by hydrated SiO 2 species through H-bonding with the lipid polar groups is entirely consistent with near-reversible adsorption. 61 The partial reversibility effected by silica nanoparticle adsorption is probably more because of a mechanical disturbance of the DOPC surface 15 rather than a strong binding between particles and DOPC. A consolidation of the interaction due to binding between the hydrated SiO 2 species and the hydrated phosphate moieties following the activation step could cause this.…”

Surface Modification of SiC Powder with Sodium Humate: Adsorption Kinetics, Equilibrium, and Mechanism

“…The adsorption kinetics equations have two main models, including the pseudo-first-order kinetics model and the pseudo-second-order kinetics model. − is the saturated form of the pseudo-first-order kinetics model and this model is commonly used to express the linear relationship between ln­( q e – q t ) and t (eq )­ In these equations, q e (mg/g) is the equilibrium adsorption capacity, q t (mg/g) is the adsorption capacity at time t , and k 1 (min –1 ) is the rate constant of the pseudo-first-order kinetics.…”

Effective modelling of adsorption monolayers built of complex molecules

“…Random sequential adsorption of such dimers may model various adsorption experiments [31,32,33], and gains increasing attention of theoretical studies [34,35,36]. In this section, the dependence of saturated packing fraction of dimers on their width-to-height ratio will be discussed [37,26,38].…”