title: Synthesis of magnetic rattle-type nanostructures for use in water treatment.
abstract: A hydrothermal technique to simultaneously remove a SiO2 template and crystallize a TiO2 outer layer was used to create magnetically separable, hollow rattle-type nanoparticles consisting of a magnetic Fe3O4 core contained within a hollow TiO2 shell. Fe3O4 cores approximately 240 nm in diameter were synthesized, subsequently coated by SiO2 and finally coated with TiO2. This was followed by a hydrothermal treatment to selectively etch the silica, resulting in rattle-type particles with a final outer shell diameter of approximately 390 nm. The product of hydrothermal treatment were rattle-type particles with increased crystallinity and a 68% increase in surface area. Characterization confirmed the ability to etch a hard SiO2 template through use of a simple and benign thermal treatment with pure water, while simultaneously introducing a crystalline phase into the TiO2 active layer. The potential of the particles to be employed as a catalyst in UV induced advanced water treatment for removal of organic contaminants was evaluated through a colorimetric photocatalytic degradation assay using methylene blue as a model contaminant. The ability of the particles to be magnetically separated from solution after treatment and recycled for consecutive treatment cycles was then demonstrated. This technique for selectively removing a hard SiO2 template while simultaneously crystallizing a TiO2 shell avoids the use of hazardous chemical etchants or complex processing, rendering the synthesis of hierarchical, multimaterial, hollow, porous rattle-type particles a simple, attractive, and environmentally friendly "one-pot" technique for potential industrial application.
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Stuart
authors.initials: S
authors.lastname: Linley
authors.forename: Timothy
authors.initials: T
authors.lastname: Leshuk
authors.forename: Frank X
authors.initials: FX
authors.lastname: Gu
mesh_terms: D002384:Catalysis; D052203:Ferrosoferric Oxide / Q000737:chemistry; D055772:Green Chemistry Technology; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008751:Methylene Blue / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry; D010316:Particle Size; D059027:Recycling; D012822:Silicon Dioxide / Q000737:chemistry; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays; D018508:Water Purification
chemical_list: D058185:Magnetite Nanoparticles; C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium; D008751:Methylene Blue; D052203:Ferrosoferric Oxide