title: Importance of acoustic shielding in sonochemistry.
abstract: It is well known that sonochemistry is less efficient at high acoustic intensities. Many authors have attributed this effect to decoupling losses and shielding of the acoustic wave. In this study we investigate both phenomena for a 20 kHz ultrasound field with an intensity ranging from 40 to 150 W/cm2. Visualization of the bubble cloud has demonstrated that the void fraction below the ultrasound horn increases more than proportional with increasing power input. Nevertheless, the energy coupling between the horn and the liquid remains constant; this implies that decoupling losses are not reinforced for larger bubble clouds. On the contrary, microphone measurements have shown that due to the larger bubble cloud a substantial part of the supplied energy is lost at high power inputs. In striving towards more efficient sonochemistry, reduction of shielding appears as one of the major challenges.
authors.affiliation: Process Development Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Maikel M
authors.initials: MM
authors.lastname: van Iersel
authors.affiliation: Process Development Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. Electronic address: n.e.benes@tue.nl.
authors.forename: Nieck E
authors.initials: NE
authors.lastname: Benes
authors.affiliation: Process Development Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Jos T F
authors.initials: JTF
authors.lastname: Keurentjes
mesh_terms: D000465:Algorithms; D002151:Calorimetry; D002621:Chemistry / Q000295:instrumentation*; D008027:Light; D010084:Oxidation-Reduction; D011193:Potassium Iodide / Q000737:chemistry / Q000528:radiation effects; D012542:Scattering, Radiation; D014465:Ultrasonics
chemical_list: D011193:Potassium Iodide