Interfacial region, pyrolysis

Kotronarou et al. (1991) detected temperatures on the order of 2000 K at the gas/liquid interfacial region. Sonochemical reactions are characterized by the simultaneous occurrence of pyrolysis and radical reactions, especially at high solute concentrations. Any volatile solute will participate in the former reactions because of its presence inside the bubbles during the oscillations or collapse of the cavities. In the solvent layer surrounding the hot bubble, both combustion and free radical reactions are possible. 

In the specific case of hydrogen sulfide gas dissolved in water, bodi pyrolysis in the vapor phase of die collapsing bubbles and hydroxyl radical attack in the quasi liquid interfacial region occur simultaneously as follows ... 

Hua et al. (1995) proposed a supercritical water region in addition to two reaction regions such as the gas phase in the center of a collapsing cavitation bubble and a thin shell of superheated liquid surrounding the vapor phase. Chemical transformations are initiated predominantly by pyrolysis at the bubble interface or in the gas phase and attack by hydroxyl radicals generated from the decomposition of water. Depending on its physical properties, a molecule can simultaneously or sequentially react in both the gas and interfacial liquid regions. 

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