Sonolytic Destruction of Trihalomethanes by Ultrasonic Irradiation

Abstract

Ultrasonic irradiation was employed for the degradation of trihalomethanes (THMs) CHCl 3 , CHBrCl 2 , CHBr 2 Cl, CHBr 3 , and CHI 3 . The effects of various reaction and sonication conditions on the sonodegradation of THMs were examined and explained by the principles of sonochemistry. Batch experiments were conducted at an ultrasonic frequency of 20 kHz and power of 18.4 W. The sonodegradation rate of the THMs increased with increasing the solution temperature or the acoustic intensity, whereas aqueous solution pH, solute concentration up to 10 mg/L, and water quality did not affect the sonolytic destruction of the THMs. Ultrasonic removal of CHCl 3 , CHBrCl 2 , CHBr 2 Cl, and CHBr 3 was not affected by the presence of other compounds as a mixture in the aqueous solution, while CHI 3 sonolysis was enhanced. Hydrogen peroxide, nitrate, chloride, bromide, and iodide were identified and quantified as the reaction inorganic products. Degradation rates and efficiencies followed the decreasing order of: CHCl 3 > CHBrCl 2 > CHBr 2 Cl > CHBr 3 > CHI 3 , while the electrical energy consumed per liter of contaminated aqueous solution treated was found to be in inverse order.