Theoretical investigation of the effect of ambient pressure on bubble sonochemistry: Special focus on hydrogen and reactive radicals production

The effect of static pressure (P-infinity) on bubble sonochemistry (i.e. hydrogen and reactive species production) is investigated on a range of ambient bubble sizes (R-0) for argon-saturated water. The used ambient pressure ranges from 0.3 to 2 atm, where its impact is shown for frequencies of 355, 500 and 1000 kHz. It is found that for each ambient pressure, the change of bubble temperature and its chemical yield profiles vs. R-0 follow a Gaussian tendency, where optimal values are inferred from these curves. Optimum pressures of 0.7 and 0.5 atm are obtained at 355 and 515 kHz for both, the bubble temperature and the production of hydrogen. The range of R-0 for active bubbles varies sensitively with P-infinity and frequency variation. The yield of H-2, O and H center dot is promoted in the regions of R-0 where the average bubbles temperature is similar to 8500 K, conversely to the production of center dot OH, which is favored at relatively lower temperatures (similar to 5500 K).

Automated summary

The study investigated the effect of static pressure on bubble sonochemistry in argon-saturated water, showing optimal values can be inferred from curves that demonstrate a Gaussian tendency. Optimal pressures for bubble temperature and hydrogen production are found at specific frequencies, indicating a sensitive variation in active bubble size range with pressure and frequency.