CHEMICAL ENGINEERING JOURNAL
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2017
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IF 6.216
Zhongqing Yu,Yabing Sun,Guyu Zhang,Chunxiao Zhang
This study investigated the degradation feasibility of N, N-diethyl-m-toluamide (DEET) in aqueous solution by water falling film dielectric barrier discharge (DBD) plasma under three different operating modes. The results exhibited that bubbling the gas of discharge area into DEET solution at the same time of DEET solution flowing through the discharge area (model-3) achieved better effect, the degradation efficiency and rate constant of 300 mL DEET solution with initial concentration of 20 mg/L could reach 76.8% and 0.0526 min −1 , respectively, after 27 min. In addition, the energy yield of model-3 was highest. The reactive species (H 2 O 2 , O 3 ) generated from the DBD system were measured, and the effects of different radical scavengers were analysed. Meanwhile, the removal efficiency of total organic carbon (TOC) in model-3 was much higher, could reach about 24%. The effects of various parameters such as discharge voltage, initial pH, gas bubbling flowrate and liquid circulation flowrate on the degradation of DEET in model-3 were further examined and it was also observed that higher discharge voltage, lower pH, larger gas bubbling flowrate and larger liquid circulation flowrate could promote the removal of DEET. Finally, the DEET degradation pathway was deduced based on HPLC-MS analysis and Gaussian calculation.
研究领域:
环境科学
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化学工程
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等离子体技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2022
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IF 4.598
Jieqi Feng,Hao Lan,Qibin Tao,Wenqing Chen,Qizhou Dai
In this study, a novel NCNS-Ce-PbO 2 electrode was prepared by electrodeposition method using the rare earth metal Ce and synthesized nitrogen-doped carbon nanosheets (NCNSs). Various characterization and electrochemical performance tests showed that the NCNS-Ce-PbO 2 electrode possessed a denser surface and smaller grains than other NCNS-PbO 2 and Ce-PbO 2 electrodes, with more active surface sites and thus could generate more hydroxyl radicals. N , N -diethyl-m-toluamide (DEET) was selected as the model contaminant to evaluate the electrochemical performance of the novel NCNS-Ce-PbO 2 electrode. The effects of initial pollutant concentration, current density, electrolyte concentration, and initial pH on the removal rates of DEET and chemical oxygen demand (COD) were investigated. Under optimal conditions, after degradation of 150 min, the removal rate of DEET and COD reached 100% and 80.52%, respectively. GC–MS was used to identify intermediate products in the degradation process. The degradation mechanism and possible degradation pathways of DEET with NCNS-Ce-PbO 2 electrode were discussed. The good stability of the NCNS-Ce-PbO 2 anode was confirmed by accelerated lifetime experiments.
研究领域:
环境科学
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电化学工程
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DOI
高影响因子
CHEMOSPHERE
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2020
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IF 5.778
Tianxin Zhu,Jing Deng,Mengyuan Xu,Anhong Cai,Cheng Ye,Jun Li,Xueyan Li,Qiongsong Li
The degradation of N,N -diethyl- meta -toluamide (DEET) in aqueous solution by the UV/monochloramine (UV/NH 2 Cl) process was examined systematically in this study. DEET was resistant to UV photolysis and chloramination, while the synchronous combination of UV irradiation and NH 2 Cl can effectively eliminate DEET, which was caused by the generation of hydroxyl radicals and reactive chlorine species. The former played the critical role in DEET degradation, while the contribution of the latter can be ignored. Under all investigated experimental conditions, DEET degradation in the UV/NH 2 Cl process followed the pseudo-first-order kinetic model. The water quality parameters exerted the complicated impact. Reducing solution pH and raising water temperature both favored the DEET removal. The presence of sulfate, humic acid and fulvic acid accelerated the degradation, while the introduction of bicarbonate and high-concentration chloride retarded the removal. The plausible degradation pathways of DEET in the UV/NH 2 Cl process were proposed through the combination of QTOF/MS analysis and DFT calculation, and mainly involved in the cleavage of C–N bond, dealkylation, mono- and polyhydroxylation. The acute toxicity of reacted solution underwent a trend of first increasing and then decreasing with the prolonged irradiation time, which can be well illustrated by quantitative structure-activity relationship analysis. Electrical energy per order was employed to determine the energy consumption and the optimal conditions were determined as UV fluence of 369.9–493.2 mJ cm −2 and NH 2 Cl dosage of 5–20 mg L −1 .
研究领域:
环境科学
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化学工程
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毒理学
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产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2021
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IF 7.312
Chengcheng Xu,Jing Deng,Shijun Zhu,Xiao Ling,Songtu Shen,Hongguang Guo,Qiongfang Wang,Xueyan Li
The introduction of ascorbic acid (AA) into Fe(III)/PS system exhibited extremely high activity on the removal of N,N-diethyl- meta -toluamide (DEET) and other pollutants. The removal efficiency of DEET within 30 min reached 90.13%, its dynamic curve obeyed second-order kinetic model and the k obs was calculated to be 0.150 L·mg −1 ·min −1 . Compared with other reducing agents, AA was tested to be the most suitable. The optimal dosages of Fe(III), PS and AA were tested to be 0.1, 1.0 and 0.5 mM, respectively. Furthermore, the introduction of AA extended the working pH to 2.5–9.3. Common anions posed different degrees of inhibition on DEET degradation at relatively high concentration, while a small dosage of HCO 3 − (<1 mM) abnormally exerted a positive role. In terms of reaction mechanism, scavenger experiment and EPR observation illustrated that ·OH and ·SO 4 − dominated DEET degradation, yet slight Fe(Ⅳ) was also found during the reaction, which indicated that Fe(Ⅳ) may also contribute to DEET removal. Different from the rapid consumption of Fe(II) in Fe(II)/PS system, Fe(II) in Fe(III)/PS/AA system entered a dynamic equilibrium state in the later stage of the reaction, which can decompose PS to form ·SO 4 − continuously. Furthermore, the reduction and chelation ability of AA both functioned a key role. According to the degradation intermediates identified by LC-MS analysis, the degradation pathways of DEET could be divided into two directions, which covered opening benzene ring and removing side chain.
研究领域:
环境科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
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