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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-Lsup-1/sup 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 minsup-1/sup) with oxygen as the sparge gas. Ozone alone decomposed alachloras quickly as sonication at 1071 kHz (k ozone = 0.045 0.004 minsup-1/sup). The fastest decompositionachieved was with the combination of ozone and sonication at either 358 or 618 kHz (average k= 0.229 0.006 minsup-1/sup). 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.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 19 File Size: 1 file , 470 KB