Effect of surface hydrophobicity on the hydrodynamic detachment of particles from surfaces

Experiments were performed to evaluate the hydrodynamic force required to d etach colloidal particles from substrates by fluids in simple shear flow, T he role of DLVO and acid-base interactions on the process of adhesion and r emoval of colloidal particles, from model surfaces, in various fluid enviro nments was investigated. Particles and substrates with varying degrees of h ydrophobicity were used. The free energy of interaction between these surfa ces in a number of fluid media was calculated using the acid-base approach. Good qualitative agreement was obtained between calculated values of free energy of interaction using the acid-base approach and the critical hydrody namic force required to detach the particles if long range electrostatic re pulsion is properly accounted for. Results for a range of particles and sub strates of varying hydrophobicity and for a range of solvents can be consis tently explained using this approach.