Scientists clarify key indicator of chemical activity: the correlation between liquid properties and the generation of active bubbles explained.
Active bubbles, also known as acoustic bubbles, show promise in applications ranging from water purification to medicine. These microbubbles are generated through a process called sonication, in which high-intensity ultrasonic waves are applied to liquids.
The energy from these waves heats and pressurizes the bubbles, creating extreme conditions. For instance, when ultrasonic waves cause bubbles in water to collapse adiabatically, temperatures inside the bubbles can exceed several thousand degrees, and pressures can reach several hundred atmospheres.
Researchers at Osaka Metropolitan University have recently identified critical indicators for evaluating the chemical activity and temperature of these microbubbles, advancing their potential use in various fields.
The group led by Professor Kenji Okitsu of the Graduate School of Sustainable System Sciences showed that, when water is undergoing sonication, the amount of hydrogen is a more important indicator of the chemical activity of acoustic bubbles than hydrogen peroxide during thermal decomposition of the water.
Experimental Analysis of Bubble Temperature and Quantity
The team also conducted experiments using an aqueous t-butanol (tertiary alcohol) solution to investigate the temperature and number of active bubbles generated when exposed to ultrasonic waves. As the temperature of the solution and the concentration of inorganic salts increased, the temperature of the active bubbles became lower and the number of active bubbles produced decreased.
“Our research provides new insights into the relationship between bubble temperature and chemical activity,” Professor Okitsu exclaimed. “As the characteristics of active bubbles become clearer, more precise control of chemical reactions will become possible. We expect further applications and progress in water purification technology and nanotechnology, such as the decomposition of persistent organic pollutants and the synthesis of highly functional, high value-added nanomaterials.”
Reference: “Evaluation of H2O2, H2, and bubble temperature in the sonolysis of water and aqueous t-butanol solution under Ar: Effects of solution temperatures and inorganic additives of NaCl and KI” by Yuki Nakata, Yoshiteru Mizukoshi and Kenji Okitsu, 7 November 2024, Ultrasonics Sonochemistry.
DOI: 10.1016/j.ultsonch.2024.107146
The study was funded by the Japan Society for the Promotion of Science.
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