Application of DLVO Energy Map To Evaluate Interactions between Spherical Colloids and Rough Surfaces

摘要

This study theoretically evaluated interactions between sphericalncolloids and rough surfaces in three-dimensional space using Derjaguin−Landau−nVerwey− Overbeek (DLVO) energy/force map and curve. The rough surfaces werenmodeled as a flat surface covered by hemispherical protrusions. A modified Derjaguinnapproach was employed to calculate the interaction energies and forces. Results shownthat more irreversible attachments in primary minima occur at higher ionic strengths,nwhich theoretically explains the observed hysteresis of colloid attachment andndetachment during transients in solution chemistry. Secondary minimum depths cannbe increased significantly in concave regions (e.g., areas aside of asperities or betweennasperities) due to sidewall interactions. Through comparing the tangential attractivenforces from asperities and the hydrodynamic drag forces in three-dimensional space,nwe showed that attachment in secondary minima can be located on open collectornsurfaces of a porous medium. This result challenges the usual belief that thenattachment in secondary minima only occurs in stagnation point regions of the porous medium and is absent in shear flownsystems such as parallel plate flow chamber and impinging jet apparatus. Despite the argument about the role of secondarynminima in colloid attachment remained, our study theoretically justified the existence of attachment in secondary minima in thenpresence of surface roughness. Further, our study implied that the presence of surface roughness is more favorable for attachmentnin secondary minima than in primary minima under unfavorable chemical conditions.