Clarification of regimes determining sonochemical reactions in solid particle suspensions

Abstract

Highlights Effect of particle size and concentration on sonochemical yields were examined. The site-increasing regime and the sound-damping regime are clarified. Adding microparticles changed from being enhancing to inhibiting at ∼ 1 vol%.

Joint effects of gas bubbles and solid particles on sonochemical inhibition in sonicated aqueous solutions

“…I 3 − production linearly increased with ultrasonic irradiation time in the test solution containing either silica particles or argon gas bubbles, as well as in the single-phase case ( Fig. 5 ), which is well aligned with the results of past studies [45] , [52] . This indicates that the formation rate of I 3 − , r f (I 3 − ), defined as the increase in I 3 − concentration per unit time, was independent of the irradiation time (≤25 min).…”

“…They ascribed this to additional nucleation sites, as well as titania’s catalytic activity [42] . Her et al [43] found that ⋅OH yields in 3–12-vol% glass bead suspensions were lower than those in water, and decreased with increasing solids fraction, which tallied with the results of other studies [44] , [45] . In more concentrated suspensions, gas/vapor diffusing through the bubble wall would be harder, which would in turn make it harder for bubbles to oscillate or collapse [46] .…”

“…(c) The presence of large amounts of solid particles and gas bubbles in the immediate vicinity of the ultrasonic horn (especially near the horn tip surface) could produce decoupling losses, minimizing the transfer of energy into the solution and decreasing the energy for the cavitation events [50] . (d) When ultrasound propagated in gas–solid–liquid mixtures, the gas and solid phases could also result in increased energy dissipation, attenuating the ultrasound and leaving even less energy available for acoustic cavitation [45] , [52] .…”

Tetracycline degradation by dual-frequency ultrasound combined with peroxymonosulfate

“…Fig. 12 displays the measurement findings, and we performed a linear fit to the results, and the slope of the fitted straight line is the production rate of H 2 O 2 ( ), μM/min) [39] , which would be used in the following section to estimate the number of active bubbles. was 0.27 μM/min or 0.06 μM/min under 20 kHz ultrasound (210 W/L) or 80 kHz (85.4 W/L) ultrasound, respectively.…”

Critical Roles of Impurities and Imperfections in Various Phases of Materials

“…Hydrophobic particles work more effectively as cavitation nuclei compared to hydrophilic particles [ 98 , 99 ]. In summary, the number, size, and hydrophobicity of impurity particles determine the acoustic cavitation threshold (or number of cavitation bubbles) [ 100 ].…”