The sonolytic decomposition of NHCs(Nitrogen Heterocyclic Compounds), such as atrazine[6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], simazine(6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine), trietazine(6-chloro-N,N,N'-triethyl-1,3, 5-triazine-2,4-diamine), in water was investigated at a ultrasound frequency of 200kHz with an acoustic intensity of 200W under argon and air atmospheres. The concentration of NHCs decreased with irradiation, indicating pseudo-first-order kinetics. The rates were in the range 1.06∼2.07(×10−2min−1) under air and 1.30∼2.59(×10−2min−1) under argon at a concentration of 200μM of NHCs. The rate of hydroxyl radicals(∙OH) formation from water is 19.8μMmin−1 under argon and 14.7μMmin−1 under air in the same sonolysis conditions. The sonolysis of NHCs is effectively inhibited, but not completely, by the addition of t-BuOH(2-methyl-2-propanol), which is known to be an efficient ∙OH radical scavenger in aqueous sonolysis. This suggests that the main decomposition of NHCs proceeds via reaction with ∙OH radical; a thermal reaction also occurs, although its contribution is small. The addition of appropriate amounts of Fenton's reagent [Fe2+] accelerates the decomposition. This is probably due to the regeneration of ∙OH radicals from hydrogen peroxide, which would be formed from recombination of ∙OH radicals and which may contribute a little to the decomposition.

• Yasuaki Maeda(Graduate School of Engineering, Osaka Prefecture University)
• Young Eok Yoo(College of Education, Daegu University) Corresponding Author