title: High-pressure liquid dispersion and fragmentation of flame-made silica agglomerates.
abstract: The influence of primary particle diameter and the degree of agglomeration of flame-made silica agglomerate suspensions in aqueous solutions is studied by high-pressure dispersion (up to 1500 bar) through a nozzle with a 125 microm inner diameter. These particles were produced (4-15 g/h) by oxidation of hexamethyldisiloxane (HMDSO) in a coflow diffusion flame reactor. Their average primary particle size (10-50 nm) and degree of agglomeration were controlled by varying the oxygen and precursor flow rates. The particles were characterized by nitrogen adsorption, electron microscopy, and small-angle X-ray scattering. Hydrodynamic stresses break up soft agglomerates and yield hard agglomerate sizes in the range of 100-180 nm, as characterized by dynamic light scattering. Soft agglomerates exhibited decreasing light scattering diameters with increasing dispersion pressure, while hard agglomerates were insensitive.
authors.affiliation: Institute for Mechanical Process Engineering and Mechanics, Universität Karlsruhe (TH), D-76128 Karlsruhe, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Wengeler
authors.forename: Alexandra
authors.initials: A
authors.lastname: Teleki
authors.forename: Markus
authors.initials: M
authors.lastname: Vetter
authors.forename: Sotiris E
authors.initials: SE
authors.lastname: Pratsinis
authors.forename: Hermann
authors.initials: H
authors.lastname: Nirschl