Decomposition of 2‐chlorophenol by sonolysis in aqueous solution saturated with various dissolved gases

Abstract

The effect of several operating factors on the decomposition of 2‐chlorophenol in aqueous solution by sonolysis was investigated in this study. Experiments conducted with the purge of Ar/O2 gas mixture of 2:1 molar ratio into aqueous solution yielded noticeably higher decomposition rate for 2‐chlorophenol (k 1 = 0.0060) possibly due to the increased solubility of the gas mixture. Sonochemical decomposition of 2‐chlorophenol was found to be more effective for experiments conducted in acidic and neutral solutions than in alkaline solutions (about 85% decomposition at solution pH 3). The sonication rate constant for the decomposition of 2‐chlorophenol was increased (0.0006 to 0.00516 at pH = 3; 0.00023 to 0.00284 at pH = 9) with sonication intensity applied between 8 and 50W cm–2. The addition of appropriate amounts of ferrous ions could increase the decomposition rate of 2‐chlorophenol by sonolysis, suggesting that Fe2+ ions may react with hydroxyl peroxide to prevent the recombination of hydroxyl free radicals.