SCIENCE OF THE TOTAL ENVIRONMENT
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2021
·
IF 7.963
Yongjun Huang,Zixiang He,Xiaobin Liao,Yusheng Cheng,Huan Qi
Carcinogenic N , N -Dimethylnitrosamine (NDMA) has been reported to generate significantly during ozonation of fuel additive unsymmetrical dimethylhydrazine (UDMH), the combined ozone/Peroxy-Monosulfate (O 3 /PMS) technology was tried for reducing its formation in this study. The influence of PMS dosages, ozone concentrations, pH, Br - and humic acid (HA) on NDMA formation from UDMH were investigated. In addition, the reduction mechanisms were explored by intermediates identification and Gaussian calculation. The results demonstrated that O 3 /PMS technology was effective on NDMA reduction, reaching an efficiency of 81% with 80 μM PMS. Higher NDMA reduction rates were achieved by O 3 /PMS with increasing pH within the scope of research (from 5 to 9), achieving a maximum of 69.9% at pH 9. The presence of bromide ion facilitated NDMA generation during ozonation, but the reduction efficiency by O 3 /PMS slightly improved from 66.3% to 70.6%. The presence of HA reduced NDMA formation in O 3 /PMS system. The contribution of SO 4 •− on NDMA reduction accounted for ~64%, which was higher than that of •OH (41.4%); however, its promotion role on conversing UDMH to NDMA was lower than O 3 . Therefore, the technology could reduce NDMA formation effectively. In addition, the results of Gaussian calculation manifested that the N atom in -NH 2 group of UDMH was easily attacked not only by •OH but also by O 3 , so it is the key path that determines final NDMA formation. This study would provide reference for reducing NDMA formation during ozonation of UDMH-containing water matrixes.
研究领域:
环境科学
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化学工程
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DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Menglan Gao,Zhibin Jiang,Xiaobin Liao,Xingji Bai,Huan Qi,Jing Zou,Wei Cao
Unsymmetrical dimethylhydrazine (UDMH) is found to generate substantial carcinogenic nitroso-dimethylamine (NDMA) during ozonation , moreover, its formation is promoted by ubiquitous bromide ions (Br − ) in water matrixes, but the mechanism is still unclear. In this study, effects of Br − on NDMA formation during ozonation of UDMH were studied, meanwhile, its promotion pathways were also determined. The results demonstrated that Br − promoted NDMA formation from UDMH during ozonation, the formation rate constant with Br − is over 7 times of that without Br − . NDMA amount raised from 142.5 to 327.5 μg/L when Br − dosages increased from 0 to 100 μM. No matter with or without Br − , the augment of O 3 dosages facilitated NDMA formation; the maximum value was achieved at pH 8. NDMA decreased dramatically from 173.8 to 123.5 μg/L with HCO 3 − raising from 0 to 160 μM, while increasing remarkably to 222.5 μg/L with SO 4 2− dosing. In addition, NOM inhibited NDMA formation from UDMH during ozonation. The mass spectrum of LC-MS/MS verified that the generation of Br-UDMH was main cause for promoting NDMA formation. Moreover, hypobromous acid (HBrO) was confirmed to be responsible for Br-UDMH formation. In addition, the position that oxidants and Br − attacked was demonstrated based on Gaussian calculation. The results of this study could provide theoretical basis for the application of ozonation in bromine-containing water matrixes.
研究领域:
环境科学
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毒理学
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化学工程
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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Jiepeng Wang,Wenhua Tong,Xuqian Wang,Panyu Li,Hao Yan,Yongkui Zhang
The leakage of unsym-dimethylhydrazine (UDMH) wastewater poses a significant threat to environment due to the enormous toxicity of UDMH and its degradation by-products. The toxicity of UDMH wasterwater is mainly due to the toxicity of nitrogen-containing products. Herein, a microwave-assisted manganese trioxide degradation strategy was proposed based on advanced oxidation process (AOPs). Under recommended reaction conditions of UDMH initial concentration 250 mg/L, initial pH of reaction solution 9, microwave power 300 W, Mn 2 O 3 dosage 10 g/L and reaction duration 1 h, a high COD degradation efficiency of 85.81 %, UDMH degradation efficiency of 99.78 % were achieved. Under this condition, the amount of nitrogen-containing products concerned in the experiment was the least. The effective degradation of UDMH and COD was benifitting from the microwave-accelerated molecular vibration and the abundant active substances catalysed by Mn 2 O 3 , especially •OH. Material characterization results indicated that Mn 2 O 3 might play a catalytic role in reaction. The degradation intermediates of UDMH were further identified by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS), and the reaction mechanism was analyzed to reveal possible degradation pathway of UDMH. Under attack of •OH, UDMH degraded into various intermediates. ECOSAR toxicity assessment software analysis and Selenastrum capricornutum toxicity experiment showed that the toxicity of UDMH decreased significantly after microwave assisted Mn 2 O 3 degradation due to the reduction of electrophilic groups. This work provides an effective method to mitigate ecological environmental harm of UMDH wastewater in practical production.
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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DOI
高影响因子
ChemistrySelect
·
2024
·Vol. 9
·期 12
·e202400219
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IF 1.9
Feng Zhou,Chen Xie,Yonggang Huo,Qingxu Yao
Graphical A series of novel MOFs based Bi x Ti y -BTC photocatalysts synthesized by the hydrothermal method for removal of UDMH from wastewater. The interconversion between Ti 3+ and Ti 4+ in Bi 1 Ti 3 -BTC promotes quick electrons transfer. And nano-Fe 3 O 4 prevented agglomeration of Bi 1 Ti 3 -BTC and improved photocatalytic activity, the optimal catalytic degradation performance of 97.02 % was observed at a Bi : Ti molar ratio of 1 : 3. Removal of organic pollutants from wastewater remains a significant challenge. Hence, we report a series of novel MOFs based Bi x Ti y -BTC photocatalysts synthesized by hydrothermal method for decontamination of 1,1-Dimethylhydrazine (UDMH). The preparation parameters of MOFs were optimized, the best catalytic performance was achieved by adjusting the Bi/Ti molar ratio to 1 : 3, with Bi 1 Ti 3 -BTC a photocurrent density of 0.35 mA/cm 2 was reached. The morphology and composition of the materials were analyzed, titanium doping increased the specific surface area. Bi 1 Ti 3 -BTC was loaded with magnetic nano-Fe 3 O 4 , which prevented agglomeration of Bi 1 Ti 3 -BTC and increased the specific surface area, thus improving photocatalytic activity. The band gap structure of the semiconductor materials was estimated by UV-Vis and XPS valence band spectra, while the separation efficiency of photogenerated carriers was investigated by photocurrent density and PL (Photoluminescence) spectrum. The photocatalytic degradation rate of UDMH rapidly decreased after addition of EDTA, indicating that h + was the main active species in the photocatalytic degradation process. The photocatalytic removal efficiency of UDMH with Bi 1 Ti 3 -BTC/Fe 3 O 4 at a concentration of 0.5 g/L reached 97.58 % after illumination for 180 min, and after 210 min near quantitative degradation was observed.
研究领域:
环境科学
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材料科学
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产品关联
DOI
高影响因子
JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING
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2020
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IF 1.724
Feng Zhou,Xianghong Ren
1,1-Dimethylhydrazine (UDMH) and its by-products were considered carcinogenic toxins and represent a serious health hazard to the population once present in water under natural conditions without treatment. The conventional degradation method suffers from incomplete removal of intermediate products (especially N-nitrosodimethylamine (NDMA)), the powdery catalysis being difficult to recover and results in high energy consumption. In this study, a series of Bi2O3/TiO2/Al2O3 (BTA) photocatalysts have been successfully synthesized by a simple dry mixing method with powder material followed by their immobilization. It was evaluated by the photocatalytic degradation of UDMH present in wastewater, which can be recovered by rapid filtration and utilizes only solar energy. The catalyst exhibited markedly enhanced photocatalytic activity for the degradation of UDMH wastewater compared with conventional TiO2/Al2O3 (TA) catalysts under UV, visible and solar irradiation. Besides, the intermediate NDMA was gradually completely degraded. The photocatalysts were extensively characterized using scanning electron microscopy, energy dispersive spectrometry, specific surface area (BET), X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy and photo-electrochemical I–t curves evaluation. The results revealed that all the BTA composites exhibited high stability and stronger absorbance in visible light. In addition, the BTA exhibited a reversible photochromic property that can effectively expand the range of light absorption and enhance the photocatalytic activity. The reversible photochromic properties of BTA explained in the proposed mechanism model are expected to be useful for detecting and sensing UDMH or other organic contaminants.
研究领域:
环境科学
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催化化学
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材料科学
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DOI
高影响因子
RSC Advances
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2026
·Vol. 16
·期 27
·24465-24481
·
IF 6.1
Jiepeng Wang,Siyu He,Zhe Wang,Yunlong Deng,Jielei Hao,Xuqian Wang,Yongkui Zhang
Unsymmetrical dimethylhydrazine (UDMH) is difficult to efficiently degrade and mineralize using traditional wastewater treatment processes, leading to the accumulation of toxic nitrogenous intermediates. In this study, a microwave-assisted catalytic degradation system based on manganese oxides was developed for effective UDMH treatment. Experiments were integrated with DFT calculations to systematically compare the structure–activity relationships of MnO2 and Mn2O3. DFT calculations show that the metallic character of Mn2O3 affords high electron mobility that favors rapid reduction of intermediates, whereas semiconducting MnO2 exhibits superior overall catalytic performance; the latter's lower oxygen-vacancy formation energy (2.10 eV vs. 2.41 eV) markedly decreases the barrier for the *OH → *O → *OOH sequence, intensifying oxidative pathways. DFT results, corroborated by XPS and XRD analyses, reveal that both oxides generate ˙OH via dynamic Mn4+/Mn3+/Mn2+ redox cycling and surface hydroxyl enrichment. However, MnO2, exhibiting higher surface ˙OH density and lower UDMH adsorption energy, leverages microwave-induced hot spots to sustain ˙OH production, achieving >90% COD removal. Mn2O3 suffers from structural deactivation that constrains long-term stability. The microwave-enhanced mechanism of Mn-based catalysis was elucidated by the three-scale analysis—electronic structure, surface adsorption and catalytic reaction. This study provides a theoretical basis for the design of manganese-based catalysts and supports their applications in the microwave-assisted treatment of nitrogen-containing wastewater.
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PubMed
高影响因子
CHEMOSPHERE
·
2016
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IF 3.698
Ying Han,Zhong-lin Chen,Ji-min Shen,Ji-he Wang,Wei-wei Li,Jun Li,Bin-yuan Wang,Li-na Tong
The role of Cu(II) in the reduction of N -nitrosodimethylamine (NDMA) with zero-valent metals was investigated by determining the effects of Cu(II) on the removal, kinetics, products, and mechanism. NDMA removal was enhanced, and all reactions followed a pseudo-first-order kinetic model except for the Fe and Fe/0.1 mM Cu(II) systems. The iron mass-normalized pseudo-first-order rate constants ( k MFe ) increased with the Cu(II) concentration. The zinc mass-normalized pseudo-first-order rate constants ( k MZn ) were identical to those with the Cu(II) concentrations from 0.1 mM to 1.0 mM and were higher with 2.0 mM Cu(II). The types of products detected were unchanged. Some unknown products were also found. NDMA was reduced to 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine , UDMH). Then, UDMH was reduced into dimethylamine (DMA) by the Fe/Cu(II) and Zn/Cu(II) systems. Catalytic hydrogenation was proposed as the reduction mechanism. Several copper species, such as Cu(OH) 2 in the Fe/Cu(II) system and Cu 2 O and Cu(OH) 2 in the Zn/Cu(II) system enhanced NDMA reduction. Differences between the Fe/Cu(II) and Zn/Cu(II) systems were caused by the reduction potentials and surface conditions of the different metals and the copper species in the various systems.
研究领域:
环境化学
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水处理
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催化
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化学工程
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产品关联
DOI
PubMed
高影响因子
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