Destruction of carbon disulfide in aqueous solutions by sonochemical oxidation

Carbon disulfide (CS2) is toxic to animals and aquatic organisms, and can also decompose to carbonyl sulfide (OCS) and hydrogen sulfide (H2S) in aqueous environment. The kinetics of the sonochemical degradation of aqueous CS2 was studied in a batch reactor at 20 kHz and 20°C, and the effects of process parameters (e.g. concentration, ultrasonic intensity, irradiating gas) investigated. The concentrations of unbuffered CS2 solutions used were (6.4-7.0) × 10-4, 10.5 × 10-4 and (13.2-13.6) × 10-4 M and the intensities were varied from 14 to 50 W. The reaction rate was found to be zero-order and the rate constant for the degradation at 20°C and 14 W in air was 21.1 μM/min using the largest initial concentration range studied. At the same initial concentration range but at 50 W (39.47 W/m2) the degradation rate of CS2 was 46.7 μM/min, more than two times that at 14 W (11.04 W/m2). The rate of CS2 sonochemical degradation in the presence of the different gases was in the order of He > air ≥ N2O > Ar; the rate with helium was found to be about three times that of argon. The formation of sulfate (SO42-) as reaction product with air as the irradiating gas was enhanced in the presence of hydrogen peroxide (H2O2) and inhibited in the presence of 1-butanol. The sonochemical oxidation of CS2 may prove to be an efficient and environmentally benign way for the removal of this hazardous pollutant from natural water and wastewater. © 2002 Elsevier Science B.V. All rights reserved.