Ultrasound-enhanced atomization of polymer solutions and applications to nanoparticles synthesis

In this paper we report the experimental results that show ultrasound-enhanced atomization of viscoelastic liquids such as gel-forming xanthan gum (Xan) solutions, and applications to nanoparticles synthesis. Contrary to the conventional view that viscoelastic liquids are more difficult to atomize than Newtonian liquids, we found that the aerodynamic conditions required to form uniform drops are less severe for some viscoelastic liquids than for liquids. Under similar aerodynamic conditions using ultrasound-modulated two-fluid (UMTF) atomization at 54 kHz, 40-/spl mu/m-diameter uniform drops were obtained for Xan solutions, but not for Newtonian aqueous glycerol of same viscosity. When sprayed into a tubular reactor under pyrolysis conditions, the drops generated by UMTF atomization yielded spherical particles which are free from holes, and also smaller and more uniform in size than those by conventional ultrasonic atomization.