AWWA WQTC60784

The sonochemical decomposition of alachlor in a batch reactor was investigated.Alachlor was irradiated with ultrasound at an input power of 128 Watts with oxygen or ozone (1mg-L^-1 in solution) as a sparge gas. The frequency of ultrasonic irradiation was varied between205, 358, 618, and 1071 kHz. A frequency of 358 kHz gave the highest degradation rateconstant (0.098 ± 0.003 min^-1) with oxygen as the sparge gas. Ozone alone decomposed alachloras quickly as sonication at 1071 kHz (k ozone = 0.045 ± 0.004 min^-1). The fastest decompositionachieved was with the combination of ozone and sonication at either 358 or 618 kHz (average k= 0.229 ± 0.006 min^-1). The addition of humic acids to the system slightly inhibited thedecomposition of alachlor. Several organic intermediates of alachlor sonolysis were identifiedby GC/MS, including 2,6-diethylaniline and 2-chloro-2',6'-diethylacetanilide. Chlorine recoverywas approximately 70 % when sonication and ozonation were combined, indicating thatmineralization of the chlorinated portion of alachlor was faster than with either technology alone. Includes 35 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

19

File Size:

1 file , 470 KB