title: Nanoparticle flotation collectors: mechanisms behind a new technology.
abstract: This is the first report describing a new technology where hydrophobic nanoparticles adsorb onto much larger, hydrophilic mineral particle surfaces to facilitate attachment to air bubbles in flotation. The adsorption of 46 nm cationic polystyrene nanoparticles onto 43 μm diameter glass beads, a mineral model, facilitates virtually complete removal of the beads by flotation. As little as 5% coverage of the bead surfaces with nanoparticles promotes high flotation efficiencies. The maximum force required to pull a glass bead from an air bubble interface into the aqueous phase was measured by micromechanics. The pull-off force was 1.9 μN for glass beads coated with nanoparticles, compared to 0.0086 μN for clean beads. The pull-off forces were modeled using Scheludko's classical expression. We propose that the bubble/bead contact area may not be dry (completely dewetted). Instead, for hydrophobic nanoparticles sitting on a hydrophilic surface, it is possible that only the nanoparticles penetrate the air/water interface to form a three-phase contact line. We present a new model for pull-off forces for such a wet contact patch between the bead and the air bubble. Contact angle measurements of both nanoparticle coated glass and smooth films from dissolved nanoparticles were performed to support the modeling.
authors.affiliation: McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7.
authors.forename: Songtao
authors.initials: S
authors.lastname: Yang
authors.forename: Robert
authors.initials: R
authors.lastname: Pelton
authors.forename: Adam
authors.initials: A
authors.lastname: Raegen
authors.forename: Miles
authors.initials: M
authors.lastname: Montgomery
authors.forename: Kari
authors.initials: K
authors.lastname: Dalnoki-Veress
mesh_terms: D000327:Adsorption; D000388:Air; D005898:Glass / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D011137:Polystyrenes; D014867:Water