The oxidation study of N,N-diethyl-meta-toluamide in dual frequency ultrasonic reactor

Authors : Zeynep EREN, Kevin O`SHEA

Pages : 94-101

Doi:10.35208/ert.749236

View : 18 | Download : 10

Publication Date : 2020-09-30

Article Type : Research Paper

Abstract :With the increasing concern of emerging contaminants insert ignore into journalissuearticles values(ECs);, advanced oxidation processes insert ignore into journalissuearticles values(AOPs); have been widely investigated to fulfill the drinking water quality because of the potential adverse health effects of ECs. Accordingly, N,N-diethyl-meta-toluamide insert ignore into journalissuearticles values(DEET); is selected as a model compound belonging ECs to monitor its ultrasonic oxidation which is one of the most popular AOPs in a dual frequency ultrasonic reactor insert ignore into journalissuearticles values(DFUR); using low-frequency probe insert ignore into journalissuearticles values(20 KHz); and high-frequency transducer insert ignore into journalissuearticles values(640 KHz); type sources. DFUR was calorimetrically optimized in terms of power densities of both ultrasonic sources in order to provide the highest sonochemical yield with efficient energy output. Pseudo-first order kinetic equation was applied to results by measuring the concentration decreasing during the oxidation reactions. The pseudo-first-order rate constants, k, increased from 7.8x10 -3 min -1 insert ignore into journalissuearticles values(640 kHz, R 2 =0.930); to 13.5x10 -3 min -1 insert ignore into journalissuearticles values(DFUR, R2=0.990);, by contrast, the rate constant was only 0.7x10 -3 min -1 insert ignore into journalissuearticles values(R 2 =0.281); for 20 kHz low-frequency ultrasonic source. DEET oxidation was evaluated with the presence of different gas saturation insert ignore into journalissuearticles values(Ar, Air, O 2 , and N 2 );; addition of hydrogen peroxide insert ignore into journalissuearticles values(PO);, persulfate insert ignore into journalissuearticles values(PS); and monoperoxysulfate insert ignore into journalissuearticles values(MPS); and PO concentration effect insert ignore into journalissuearticles values(molar ratio of DEET:PO; 1:1, 1:2, 1:5, 1:10 and 1:20);. The DEET oxidation rate was calculated as 35.8 x10 -3 min -1 insert ignore into journalissuearticles values(R 2 =0.994); in the presence of Argon gas saturation, while it was 13.5 x10 -3 min -1 insert ignore into journalissuearticles values(R 2 =0.990); when no gas bubbling. Therefore, the main degradation pathway was predicted as pyrolysis taking place inside the cavitation bubble where DEET molecules can reach. On the other side, a lower degradation rate in the presence of PO, PS, and MPS than that of no additives has indicated that the bulk phase degradation pathway for some part of DEET molecules are still occurred.
Keywords : DEET, dual frequency ultrasound, emerging contaminants ECs,