Reaction mechanism and kinetic modeling of DEET degradation by flow-through anodic fenton treatment (FAFT).
ABSTRACT The previously developed batch anodic Fenton treatment (AFT) technology has been successfully applied to degrade various pesticides in aqueous solution. The goal of this work is the development of a flow-through AFT system (FAFT) which is critical to bringing this technology into practical general use in the field. For this purpose, the degradation of DEET (N,N-diethyl-3-methylbenzamide), an insect repellent, and nine model amides was studied. Oxidation products of these compounds in FAFT were identified by GC/MS, and the results revealed that various -OH additions (most likely on the aromatic ring), quinone/keto product formation, and dimerization/bimolecular disproportionation are the major reaction pathways. This proposed overall reaction mechanism was then combined with the basic Fenton's mechanism to model the kinetics of various active species in FAFT including DEET, Fe2+, H2O2, and total iron under different reaction conditions. In addition, both initial and steady-state hydroxyl radical concentrations were measured in FAFT using benzoic acid as a chemical probe; the measured *OH concentrations were best-fitted exponentially. On the basis of the obtained [*OH] trend and the mass balance of the FAFT system, a simple FAFT model was developed to fit all of the degradation data of DEET and the model amides.
- SourceAvailable from: ocean.kisti.re.kr[Show abstract] [Hide abstract]
ABSTRACT: The degradation behavior of berberine is examined using GC-MS to select the fingerprint products that can be used to identify berberine dye in badly faded archaeological textiles. A total of thermal and degradation systems were used to degrade berberine chloride 0.1% solution up to 408 hours. The samples were analyzed using the GC-MS. Dihydroberberine, 2-pteridinamine, 6,7-dimethyl-N-[(trimethylsilyl) oxy]-, and 8-methoxy-11-[3-methylbutyl]-11H-indolo[3,2-c]-quinoline, 5-oxide were detected as the major products of thermal degradation and identified as the fingerprint products for berberine dye at the early stage of degradation. Isobenzofuran-1,3-dione,4,5-dimethoxy-, 9H-fluorene,3,6-bis(2-hydroxyethyl)-,1,3-dioxolo[4,5-g]isoquinolin-5(6H)-one,7,8-dihydro-, and 3-tert-butyl-4-hydroxyanisole were detected as the major products generated by the degradation and identified as the fingerprint products for berberine dye under severe degradation conditions.Journal of the Korean Society of Clothing and Textiles. 12/2009; 33(12).
- [Show abstract] [Hide abstract]
ABSTRACT: Two representative substances of the so-called emerging compounds group (ECs), N,N-diethyl-m-toluamide (DEET) and nortriptyline hydrochloride, were selected to be subjected to ozonation processes, which constitute promising technologies for the removal of hazardous pollutants. The kinetic study provided ozonation rate constants, with an average value of 0.123 ± 0.003 L·mol–1·s–1 for DEET, which remained almost unaffected with the pH; while values varying from 2.40 × 103 to 472 × 103 L·mol–1·s–1 for nortriptyline were deduced in the pH range 2–11. Because of the ionic nature of nortriptyline, the specific rate constants of the protonated and neutral species were determined, the values obtained being 2.1 × 103 and 4.3 × 105 L·mol–1·s–1, respectively. By means of liquid chromatography time-of-flight mass spectrometry analysis, the main byproducts formed in the ozonation reactions were identified (14 for DEET and 27 for nortriptyline), and the evolution of their concentrations with reaction time were established. According to these compounds and their concentration profiles, the reaction mechanisms for the ozonation of both emerging contaminants were proposed and discussed. A decrease in the toxicity was also observed during ozonation of nortriptyline.Industrial & Engineering Chemistry Research 11/2013; 52(48):17064–17073. · 2.24 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Degradation products of the dye extracted from turmeric and the turmeric dyed textiles were examined by using GC-MS after 100 oven (OV) and (PER) treatments for up to 28 days. Throughout the OV degradation times, 2-propenoic acid, 3-(2-hydroxyphenyl)- was found consistently, while isovanillin, and vanillic acid were newly detected. In 28 day PER degradation sample, feruloylmethane, 2-propenoic acid, 3-(2-hydroxyphenyl)-, benzoic acid, and vanillic acid were detected as well as isovanillin. Feruloylrnethane, and 2-propenoic acid, 3-(2-hydroxyphenyl)- were detected from the degraded fabric samples. With the absence of curcuminoids in the GC-MS result, the decreasing pattern of 2-propenoic acid, 3-(2-hydrokyphenyl)- reflect the degradation of curcuminoids in turmeric extraction with the progression of OV degradation times. It is suggested that isovanillin, feruloylmethane, 2-propenoic acid,3-(2-hydroxyphenyl)-, and vanillic acid are the probable fingerprint products for determining the turmeric dye from the badly faded archaeological textiles.Journal of the Korean Society of Clothing and Textiles. 06/2007; 31(6).