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Showing 1 to 20 of 25 for “"hydrophobic force"”.
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Modeling Flotation from First Principles Using the Hydrophobic Force as a Kinetic Parameter
… In flotation, a desired mineral is rendered hydrophobic by surfactant coating as a means to destabilize the TLFs, so that they can be attached to the hydrophobic air bubbles. A TLF ruptures when the disjoining pressure (or surface forces per unit area) of the film becomes negative, i.e., Π < …
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Surface Forces in Foam Films
Fundamental studies of surface forces in foam films are carried out to explain the stability of foams and froths in froth flotation. The thin film pressure balance (TFPB) technique was used to study the surface forces between air bubbles in water from equilibrium film thickness and dynamic film …
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Creating long-range hydrophobic forces by coadsorption of ionic and neutral surfactants
A Mark IV surface force apparatus was used to measure surface forces between mica surfaces in dodecylamine hydrogen chloride (DAHCI) solutions at pH 5.7 in the presence and absence of long-chain alcohols. With DAHCI alone, only "short-range" hydrophobic forces were observed with decay lengths of …
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Hydrophobic Forces in Flotation
An atomic force microscope (AFM) has been used to conduct force measurements to better understand the role of hydrophobic forces in flotation. The force measurements were conducted between a flat mineral substrate and a hydrophobic glass sphere in aqueous solutions. It is assumed that the …
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Effect of Non-Ionic Surfactants and Nano-Particles on the Stability of Foams
… the van der Waals-dispersion and double-layer forces to the disjoining pressure of the film. The discrepancy may be attributed to the presence of hydrophobic force, the magnitude of which has been estimated using the Reynolds lubrication approximation. It has been found that the attractive …
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Studies of Thin Liquid Films Confined between Hydrophobic Surfaces
Surface force measurements previously conducted with thiolated gold surfaces showed a decrease in excess film entropy (£GSf), suggesting that hydrophobic force originates from changes in the structure of the medium (water) confined between hydrophobic surfaces. As a follow-up to the previous study, …
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AFM surface force measurements between hydrophobized gold surfaces
… measurements of a hitherto unknown attractive force between two mica surfaces hydrophobized in cetyltrimethylammonium bromide (CTAB) solutions. Follow-up experiments conducted by many investigators confirmed their results, while others suggested that the "hydrophobic force" is an artifact due …
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Studies of Bitumen Aeration
… by considering the contributions from the hydrophobic and steric forces in addition to the classical DLVO forces. It has been found that the hydrophobic force increases with increasing temperature, which corroborates well with contact angle data. Dynamic contact angle measurements show that …
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Application of Extended DLVO Theory: Modeling of Flotation and Hydrophobicity of Dodecane
… by considering both hydrodynamic and surface forces involved in the process. A stream function was used to estimate the kinetic energies for thinning the water films between bubbles and particles, which were compared with the energy barriers, created by surface forces, to determine the …
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Modeling bubble-particle interactions in flotation using hydrophobic solid surfaces
An atomic force microscope (AFM) was used to measure surface forces between a glass sphere and a flat fused silica plate under a number of conditions. Hydrophobic surfaces exhibiting contact angles ranging from 0 to 109° were prepared by reacting silica with octadecyltrichlorosilane (OTS). Contact …
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Validation and Application of a First Principle Flotation Model
… interaction and by increasing the hydrophobic force in wetting films. The former is controlled by energy dissipation rate (𝜀), while the latter is controlled by collector additions. The model consists of a series of analytical equations to describe bubble generation, bubble-particle …
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Surface Forces in Thin Liquid Films of H-Bonding Liquids Confined between Hydrophobic Surfaces
Hydrophobic interaction plays an important role in biology, daily lives, and a variety of industrial processes such as flotation. While the mechanisms of hydrophobic interactions at molecular scale, as in self-assembly and micellization, is relatively well understood, the mechanisms of macroscopic …
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Hydrophobic Forces in Free Thin Films of Water in the Presence and Absence of Surfactants
… different system were studied to investigate the forces interacting in thin liquid films. In the former, direct force measurements were conducted with bitumen-coated mica surfaces using a Mark IV surface force analyzer. Besides long-range electrostatic repulsive forces at separation distances …
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Development of a turbulent flotation model from first principles
… suspension (pulp), so that bubbles coated with hydrophobic particles rise to the top and form a froth phase while hydrophobic particles stay in suspension. The selectivity of the flotation process is determined by the hydrophobicity of the particulate materials involved, while the kinetics of …
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Direct Force Measurement between Surfaces Coated with Hydrophobic Polymers in Aqueous Solutions and the Separation of Mixed Plastics by Flotation
… process is based on rendering a selected mineral hydrophobic using an appropriate hydrophobizing reagent (collector), so that it can selectively attach onto the surfaces of a rising stream of air bubbles. Thus, controlling the hydrophobicity of the minerals to be separated from each other is of …
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Hydrophobic Forces in Wetting Films
… however, both the double-layer and dispersion forces are repulsive, which makes it difficult to model the rupture of the wetting films using the DLVO theory. In the present work, we have measured the kinetics of film thinning between air bubble and flat surfaces of gold and silica. The former …
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Surface and Hydrodynamic Forces in Wetting Films
… other is to directly determine the interaction forces using the force apparatus for deformable surfaces (FADS) developed in the present work. The former is designed to obtain spatiotemporal profiles of unstable wetting films by recording the optical interference patterns. The kinetic information …
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Interfacial Phenomena and Surface Forces of Hydrophobic Solids
At the molecular level the entropic “hydrophobic effect” is responsible for high interfacial energies between hydrophobic solids and aqueous liquids, the low solubility of apolar solutes in aqueous solvents, and self-assembly in biological processes, such as vesicle formation and protein folding. …
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Surface Forces between Silica Surfaces in CnTACl Solutions and Surface Free Energy Characterization of Talc
… methods. <i>One</i> is to directly measure the forces between two interacting surfaces in media. <i>The other</i> is to study the interfacial surface free energies of the particles in suspension. Direct surface force measurements were conducted between silica surfaces in …
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Modeling Bubble Coarsening in Froth Phase from First Principles
… nm, the disjoining pressure created by surface forces in the films also begins to control the film drainage rate and affect the waves motions at the air/water interfaces. If the disjoining pressure is negative, both the film drainage and the capillary wave motion accelerate. When the TLF thins …
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