Sonolysis of organic liquid: effect of vapour pressure and evaporation rate

Abstract

Various kinds of organic liquids, such as hydrocarbons, ethers, ketones and alcohols, were subjected to ultrasonic irradiation and the effects of vapour pressure and evaporation rate of the liquids on decomposition rates and the distribution of decomposition products were investigated. The main decomposition products from hydrocarbons were hydrogen, methane, ethylene and acetylene, and hydrogen, methane, ethylene, carbon monoxide and aldehydes from alcohols. The decomposition rates of organic liquids were generally faster than that of water, and the reaction would proceed via gas-phase chain reactions in the high temperature site by comparison of the product with pyrolysis data in the literature and by considering the results of DPPH experiments. In the relationship between decomposition rate and vapour pressure, different features were observed in alcohols and other liquids. The hydrocarbons most efficiently decomposed under conditions in which their vapour pressures ranged from 0.1 to 0.5 Torr. On the other hand, the most efficient vapour pressure for alcohol sonolysis was about 15 Torr. The deviations became smaller when the evaporation rate was employed instead of vapour pressure, and as the reactive index of sonolysis of organic liquids, evaporation rate may be a better probe than vapour pressure, which is often chosen as the index.