title: Spontaneous Detachment of Colloids from Primary Energy Minima by Brownian Diffusion.
abstract: The Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy profile has been frequently used to interpret the mechanisms controlling colloid attachment/detachment and aggregation/disaggregation behavior. This study highlighted a type of energy profile that is characterized by a shallow primary energy well (i.e., comparable to the average kinetic energy of a colloid) at a small separation distance and a monotonic decrease of interaction energy with separation distance beyond the primary energy well. This energy profile is present due to variations of height, curvature, and density of discrete physical heterogeneities on collector surfaces. The energy profile indicates that colloids can be spontaneously detached from the shallow primary energy well by Brownian diffusion. The spontaneous detachment from primary minima was unambiguously confirmed by conducting laboratory column transport experiments involving flow interruptions for two model colloids (polystyrene latex microspheres) and engineered nanoparticles (fullerene C60 aggregates). Whereas the spontaneous detachment has been frequently attributed to attachment in secondary minima in the literature, our study indicates that the detached colloids could be initially attached at primary minima. Our study further suggests that the spontaneous disaggregation from primary minima is more significant than spontaneous detachment because the primary minimum depth between colloid themselves is lower than that between a colloid and a collector surface.
authors.affiliation: Department of Soil and Water Sciences, China Agricultural University, Beijing, 100193, China.|College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning, 110866, China.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware, 19716, United States of America.
authors.forename: Yan
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Soil and Water Sciences, China Agricultural University, Beijing, 100193, China.
authors.forename: Chongyang
authors.initials: C
authors.lastname: Shen
authors.affiliation: Department of Soil and Water Sciences, China Agricultural University, Beijing, 100193, China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Soil and Water Sciences, China Agricultural University, Beijing, 100193, China.
authors.forename: Yuanfang
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Soil and Water Sciences, China Agricultural University, Beijing, 100193, China.
authors.forename: Baoguo
authors.initials: B
authors.lastname: Li
mesh_terms: D003102:Colloids / Q000737:chemistry*; D004058:Diffusion; D015416:Maillard Reaction; D008956:Models, Chemical; D010316:Particle Size; D013499:Surface Properties
chemical_list: D003102:Colloids