Eur. Phys. J. E (2012) 35: 69
https://doi.org/10.1140/epje/i2012-12069-x

Regular Article

Brownian dynamics simulation of monolayer formation by deposition of colloidal particles: A kinetic study at high bulk particle concentration

¹ Colloids Group, Institute of Chemistry, University of Antioquia, A.A. 1226, Medellin, Colombia
² Biocolloid and Fluid Physics Group, Applied Physics Department, University of Granada, Campus Fuentenueva, 18071, Granada, Spain

^* e-mail: casanova@exactas.udea.edu.co

Received: 23 March 2012
Revised: 30 June 2012
Accepted: 10 July 2012
Published online: 8 August 2012

Abstract

Brownian dynamics simulations (BDS) of sedimentation and irreversible adsorption of colloidal particles on a planar surface were carried out at bulk particle volume fractions (φ) in the range 0.05 to 0.25. The sedimentation and adsorption of colloidal particles were simulated as a non-sequential process that allows simultaneous settling and adsorption of particles. A kinetic model for the formation of particle monolayers based on the available surface fraction (θ _A ) is proposed to predict simulation results. The simulations show a value of 0.625 for the maximum fractional surface coverage (θ _∞) and a monolayer structure insensitive to φ. However, the kinetic order of the monolayer formation process has a strong dependence with φ, changing from a value close to a unit, at low φ, to a value around two at high φ. This change in the kinetic reaction order is associated to differences of particle adsorption mechanism on the surface. At low φ values, the monolayer formation is achieved by independent adsorption of single particles and the reaction order is close to 1. At high φ values, the simultaneous adsorption of two particles on the surface leads to an increase of the reaction order to values close to 2.