Intensification of sonochemical reactions in solid-liquid systems under fully suspended condition

Abstract

Process intensification of sonochemical reactions due to the addition of solids is studied using very high solids concentrations (up to 0.5 (v/v)). The impacts of particle size, surface roughness, and solids concentration on sonochemical yields were studied experimentally by measuring the concentration of I3− formed in the cavitation of potassium iodide solution in an agitated baffled tank fitted with an ultrasonic generator (20kHz, 131W). Solids used were cation exchange resin (625μm), sand (303μm), and spherical glass beads (207, 551 and 1290μm). It was found that, due to the net effect of wave attenuation and increased number of nucleation sites available, cavitation level initially decreases with increasing solids concentration up to 0.1 (v/v), then increases up to 0.4 (v/v), followed by a further decrease. Cavitation activity increases with increasing particle diameter due to the reduction in the liquid tensile strength in the presence of larger particles, which decrease the cavitation threshold. The cavitation level is found to be enhanced due to an increase in the surface roughness. The results imply that particle size, concentration, and surface roughness all play important roles in the formation and subsequent collapse of cavities, which cumulatively influence sonochemical reaction yields.