SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Menglan Gao,Zhibin Jiang,Xiaobin Liao,Huan Qi,Lei Zhao,Chao Chen,Danielle Westerman
Aliphatic amines, common constituents that contribute to dissolved organic nitrogen (DON), can quickly react with ozone due to the lone electron pair on the nitrogen atom and this may produce carcinogen N -Nitrosodimethylamine (NDMA). 3-(Dimethylamino)-1-propylamine (DMAPA) was chosen as a representative to elucidate the NDMA formation characteristics, kinetic rates, reaction pathways, and influencing factors during ozonation in this study. The results demonstrated that NDMA generated directly from DMAPA during ozonation. Moreover, the NDMA yields increased with ozone dosages. The NDMA molar yield increased and then decreased when the pH raised from 5 to 9, achieving the maximum value at pH 8. Hydroxyl radical (∙OH) played a promotional role in NDMA formation, and its scavenger dramatically cut down its yields. Low levels of Br − facilitated NDMA formation, while the value significantly reduced when Br − was up to 1 mM. The NDMA amount was slightly raised by NO 2 − , but it was inhibited by NH 4 + and NO 3 − . Moreover, it was also depressed by co-existing components in actual lake water. Based on the result of the Gaussian calculation, the LC-MS/MS and GC–MS analysis, four possible transformation pathways were proposed. The radical recombination was verified to be the primary pathway for ozone promoting NDMA formation from DMAPA.
研究领域:
环境科学
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化学
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PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Zi-jun Dong,Cheng-chun Jiang,Yue Zhou,Yu-yang Ning,Xiao-hui Sun,Guo Lv
This study investigates the Hydroxylamine (HAm)-driven Cu(II)/peroxymonosulfate (PMS) system, known for promoting toxic nitro(so)phenols formation during phenol degradation. It focuses on the intricate factors affecting nitro(so)phenols formation, aiming to unravel the complex mechanisms in the transformation of phenol to nitro(so)phenols within the HAm-Cu(II)/PMS system. Findings reveal that reaction conditions significantly impact the formation of nitro(so)phenols by affecting the phenol degradation intermediate (PhO • ) and HAm oxidation reactive nitrogen species (•NO, •NO 2 ). Additionally, the levels of specific reactants and coexisting compounds also affect the pathway of nitro(so)phenols formation. At high concentrations of HAm and halogen, the •NO and halogen radicals generated may directly oxidize phenol to produce PhO • , which in turn reacts with •NO and •NO 2 , and thus establishing a different nitro(so)phenols formation path from that dominated by S O 4 ∙ - . The oxidation products and driving factors of HAm vary at different stages, affecting the production of nitro(so)phenols. Moreover, the presence of halogen and natural organic matter (NOM) alters the formation of nitro(so)phenols under real water conditions compared to pure water. Overall, the investigation into various influencing factors indicates that advanced oxidation process enhanced by hydroxylamine, not just limited to persulfate-related reactions, has the potential to produce nitro(so)phenols when treating phenol-containing water.
研究领域:
环境科学
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化学工程
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DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 2
·396
·
IF 4.2
Zhenkun Sun,Zhenyi Chen,Marie Celine Chung Lan Mow,Xiaowen Liao,Xiaoxuan Wei,Guangcai Ma,Xueyu Wang,Haiying Yu
The unrestricted utilization of antibiotics poses a critical challenge to global public health and safety. Levofloxacin (LEV) and sulfaphenazole (SPN), widely employed broad-spectrum antimicrobials, are frequently detected at the terminal stage of water treatment, raising concerns regarding their potential conversion into detrimental disinfection byproducts (DBPs). However, current knowledge is deficient in identifying the potential DBPs and elucidating the precise transformation pathways and influencing factors during the chloramine disinfection process of these two antibiotics. This study conducts a comprehensive analysis of reaction pathways, encompassing piperazine ring opening/oxidation, Cl-substitution, OH-substitution, desulfurization, and S−N bond cleavage, during chloramine disinfection. Twelve new DBPs were identified in this study, exhibiting stability and persistence even after 24 h of disinfection. Additionally, an examination of DBP generation under varying disinfectant concentrations and pH values revealed peak levels at a molar ratio of 25 for LEV and SPN to chloramine, with LEV contributing 11.5% and SPN 23.8% to the relative abundance of DBPs. Remarkably, this research underscores a substantial increase in DBP formation within the molar ratio range of 1:1 to 1:10 compared to 1:10 to 1:25. Furthermore, a pronounced elevation in DBP generation was observed in the pH range of 7 to 8. These findings present critical insights into the impact of the disinfection process on these antibiotics, emphasizing the innovation and significance of this research in assessing associated health risks.
研究领域:
环境科学
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公共卫生
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化学工程
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DOI
PubMed
高影响因子
CHEMOSPHERE
·
2017
·
IF 4.208
Xiaoxue Pan,Liqing Yan,Ruijuan Qu,Zunyao Wang
The goals of this study were to bring forward new data and insights into the effect of activation methods, operational variables and reaction pathways during sulfate radicals-based oxidation of benzophenone-3 (BP-3) in aqueous solution. Heat, transition metal ions (Fe 2+ , Cu 2+ , Co 2+ ), UV and visible light irradiation were used to activate persulfate (PS) to degrade BP-3. The results showed that these three activation methods can remarkably enhance BP-3 removal efficiency. Under the conditions of [BP-3] 0 : [PS] 0 = 1: 500, pH = 7.0, and 40 °C, complete removal of BP-3 (1.31 μM) was observed in 3 h. In the pH range of 3.0–9.0, the degradation of BP-3 decreased with increasing pH. Increasing the PS dosage accelerated the reaction, while the presence of humic acid (HA) significantly inhibited the efficiency of BP-3 removal. Based on electron paramagnetic resonance (EPR) and radical quenching studies, sulfate and hydroxyl radicals contributed to the oxidation process. According to the evolution of BP-3 and its 7 by-products, as well as frontier electron densities (FED) calculation, two routes were proposed involving hydroxylation, demethylation and direct oxidation. On the whole, this work is a unique contribution to the systematic elucidation of BP-3 removal by PS.
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
CHEMOSPHERE
·
2018
·
IF 4.427
Yijing Xia,Qizhou Dai
In this work, the electrochemical degradation of antibiotic levofloxacin (LFX) has been studied using a novel rare earth La, Y co-doped PbO 2 electrode. The effect of applied current density, pH value and initial LFX concentration on the degradation performance were systematically evaluated. The results demonstrated that electrochemical oxidation of LFX over the La-Y-PbO 2 electrode was highly effective and the reaction followed an apparent first-order kinetic model. Considering the degradation efficiency and energy efficiency, the relative optimal conditions are identified as current density 30 mA cm −2 , pH 3 and initial LFX concentration 800 mg L −1 . According to the identified products, a reaction mechanism has been proposed and the products were further oxidized to CO 2 , H 2 O, NH 4 + , NO 3 − and F − . A total of four aromatic intermediate products of LFX degradation were identified and the different structural changes to the LFX molecule included pepiperazinyl hydroxylation, decarboxylation and defluorination .
研究领域:
环境科学
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电化学工程
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DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Lijun Niu,Jianguo Li,Siqin Wang,Kyriakos Manoli,Lei Zhang,Xin Yu,Mingbao Feng
The transformation of extracellular DNA (e.g., antibiotic resistance genes) in water has attracted increasing attention over the last decades. To date, the effect of the resulting byproducts (e.g., DNA bases) on the degradation of micropollutants by oxidants remains largely unknown. In this study, four DNA bases (i.e., deoxyadenosine (dA), deoxythymidine (dT), deoxycytidine (dC), and deoxyguanosine (dG)) were investigated as potential permanganate (Mn(VII)) activators for the oxidation of tetracycline (TC) in water. The dC exhibited the best performance, e.g., the first-order rate constant of TC increased from 0.082 min −1 in the absence of dC (i.e., Mn(VII) alone) to 0.290 min −1 in the presence of 500 µM dC (i.e., Mn(VII)/dC system). The degradation of three other emerging micopollutants (i.e., bisphenol F (BPF), bisphenol S (BPS), and methotrexate (MTX)) by Mn(VII)/dC was also greater than Mn(VII) alone. Multiple lines of evidence suggested that the synergistic effect of in-situ formed MnO 2 colloids and Mn(VII) had a major role in the observed enhancement compared to radicals, Mn(VI), Mn(V) or Mn(III). The transformation products (TPs) of TC by Mn(VII) with and without dC were tentatively identified, from which the reaction pathways were proposed. Despite the high degradation of micropollutants by Mn(VII)/dC system, the majority of TPs were recalcitrant to biodegradation with multi-endpoint adverse health effects on different aquatic organisms, as indicated by in silico prediction software. Overall, this study unveiled the free DNA bases as in-situ Mn(VII) activators for removing emerging contaminants of global concern from water. However, the secondary environmental risks related to the TPs need to be considered in terms of water safety assessment.
研究领域:
环境科学
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化学
·
生物学
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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Yaling Li,Tianlie Luo,Minhui Yang,Guo Liu,Xian Chen,Yihua Li,Chengzhi Zhou,Willie J.G.M. Peijnenburg
The combustion of agricultural and forestry residues, along with subsequent runoff, can lead to the production of a significant quantities of dissolved black carbon (DBC), which plays a pivotal role in the photo-transformation of organic pesticides. As a result, the photochemical activity of DBC and its associated photo-transformation mechanisms must elucidate. This study investigated the effect of DBC on tetrachlorantraniliprole (TCTP) photo-transformation, a new type of pesticide independently developed and widely used in China, using photochemical simulation experiments. The results revealed that the prepared DBC had a smaller molecular weight and higher aromaticity, generating 3 DBC*, ·OH, and 1 O 2 , with apparent quantum yields of 4.75 × 10 −2 , 4.35 × 10 −5 , and 4.01 × 10 −2 , respectively. 3 DBC* was the dominant intermediate reactive responsible for accelerating TCTP photolysis by determining its direct photolysis rate constant as 0.278 min −1 . The degradation pathway of TCTP mainly involved nucleophilic substitution, dechlorination, and cleavage of the C–N bond. Notably, TCTP can photo-generate the cross-condensation products only in the presence of DBC. Ecotoxicity and organ-specific toxicity analysis demonstrated reduced environmental risks compared to TCTP for both direct photoproducts, as well as those mediated by DBC. These findings highlighted how DBC altered the photo-transformation pathway leading to decreased environmental risk-associated amide pesticides.
研究领域:
环境科学
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农药化学
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光化学
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DOI
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 87
·46689-46696
·
IF 3.708
Wei-fang Chen,Ling Pan,Li-fang Chen,Qiong Wang,Chang-cheng Yan
Nano zero-valent iron (nZVI) and activated carbon composites were synthesized and employed to remove hexachlorobenzene (HCB). Methods of impregnation and adsorption were employed to firstly load iron salt onto activated carbon, and thus loaded iron was then reduced to form zero valent iron. Results indicate that the method of iron loading significantly impacted the amount of iron and HCB dechlorination. In general, nZVI/activated carbon composite synthesized using an adsorption method showed considerably higher removal efficiency and dechlorination capability. More than 80% of the HCB was dechlorinated after 48 h. The dechlorination of HCB followed a stepwise pathway: HCB (hexachlorobenzene) → PCB (pentachlorobenzene) → 1,2,4,5 TeCB (tetrachlorobenzene) → TriCB (trichlorobenzene) → 1,4 DCB (dichlorobenzene) → MCB (monochlorobenzene). Compared with activated carbon or nZVI, nZVI/activated carbon composite showed much higher HCB removal. Analysis of mass partition on solid and aqueous phases indicates that most of the HCB and its dechlorination intermediates were retained on solids probably due to the strong adsorption on activated carbon. In summary, activated carbon performs three important functions: it alleviated the limitation of nZVI agglomeration, contributed to HCB removal due to its own adsorption capability and increased the resistance of nZVI against pH change.
研究领域:
环境科学
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化学工程
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DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Miao Li,Yijun Shi,Sainan Sun,Yunkun Qian,Dong An
Chloroacetonitriles (CANs) are highly toxic nitrogenous disinfection by-products (N-DBPs), which frequently appear in water supply systems and have attracted widespread attention. UV/persulfate (PS) is an effective method to degrade CANs. Bromide (Br − ) is widespread in aquatic environments and reacts with oxidative radicals to produce secondary reactive bromine species (RBS), which affects the degradation of CANs by UV/PS. It was found that the degradation of CANs was highly inhibited by Br − . The apparent first-order reaction rate constants of monochloroacetonitrile (MCAN), dichloroacetonitrile (DCAN) and trichloroacetonitrile (TCAN) decreased from 2.63 × 10 −3 , 2.00 × 10 −3 and 8.66 × 10 −4 s −1 to 2.58 × 10 −4 , 1.61 × 10 −4 and 1.59 × 10 −4 s −1 , respectively after adding 20 μM of Br − . HO• was the main radicals contributing to the degradation of CANs when the concentration of Br − was less than 10 μM, compared with SO 4 •− and direct photolysis. When the concentration of Br − was up to 20 μM, the contributions of RBS accounted for 85.7%, 90.7% and 89.9% of the apparent degradation rate constants of CANs, respectively. During the reaction, about 65% of nitrogen atoms were transformed into NO 3 − by the C C bond cleavage and oxidation. The yields of Cl − by dechlorination reaction accounted for 83.5%, 71.0% and 41.2% of the chlorine contents in MCAN, DCAN and TCAN, respectively. It was verified that CANs react with free bromine (HOBr) to produce bromochloroacetonitrile (BCAN). DCAN and TCAN are hydrolyzed to produce corresponding haloacetamides (HAMs), which are further reacted with HOBr to produce bromodichloroacetic acid (BDCAA). Furthermore, the generation of bromate was also worth noting via the oxidation of Br − in the UV/PS system.
研究领域:
环境科学
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化学工程
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PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Pengtao Cai,Tong Chen,Mingxiu Zhan,Xiaojun Ma,Masaki Takaoka,Chen Sun,Xiaodong Li
Global concern over per- and polyfluoroalkyl substances (PFASs), especially perfluorooctane sulfonate (PFOS), disposal prompts the search for effective degradation methods. Subcritical water hydrothermal treatment shows promise but suffers from unclear degradation pathways, hindering engineering application design due to unknown intermediate products. This study introduces Fe-based amorphous alloy to enhance the subcritical water hydrothermal degradation of PFOS, achieving a degradation rate of approximately 85 % under optimized conditions of 325 °C and 1 M sodium bicarbonate (NaHCO₃), compared to 56 % without the alloy. Analysis of liquid and gas-phase products, along with identification of potential intermediate products, led to proposing a reaction pathway for Fe-based amorphous alloy-enhanced subcritical water hydrothermal PFOS degradation. Additionally, the distribution of fluorine in PFOS was determined by fluorine-19 nuclear magnetic resonance ( 19 F NMR), and the energy changes of key degradation steps were calculated based on DFT, which provided concrete evidence for the degradation process and verified the mechanism of subcritical hydrothermal degradation of PFOS enhanced by Fe-based amorphous alloys. Most importantly, the Fe-based amorphous alloy demonstrated effectiveness upon repeated use after water washing. These results endorse its potential as a PFOS degradation catalyst.
研究领域:
环境科学
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材料科学
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化学工程
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DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Yao Lu,Jun-Kun Liang,Hai-Yan Wang,Chao Wang,Zhi-Min Song,Qing Hu,Qian-Yuan Wu
Tannic acid is ubiquitously present in various simulated and real water sources and in wastewater. Various chlorinated disinfection byproducts (Cl-DBPs) are generated via reactions with tannic acid during disinfection with chlorine. We used high-resolution mass spectrometry in combination with our self-developed halogen extraction code to selectively identify Cl-DBPs. Our strategy enabled successful detection of 35 Cl-DBP formulas formed by chlorination of tannic acid, and we identified 26 of these structures. The structures of 17 novel Cl-DBPs are firstly reported here. The reaction pathways of these Cl-DBPs were tentatively proposed. These Cl-DBPs are likely to be generated during chlorination at various chlorine doses, from 0.0 to 10.0 mg-Cl 2 /L, and 14 of the 26 Cl-DBPs were detected in simulated drinking water , which implies a relatively high probability of incidence. Quantitative structure-activity relationship toxicity analyses predicted that most of these Cl-DBPs would exhibit much higher acute toxicity than the common DBPs trichloromethane and monochloroacetic acid and that some of these compounds would induce developmental toxicity and be mutagenic, which further emphasizes that these Cl-DBPs should raise concerns. This study broadens our understanding of the Cl-DBPs formed from tannic acid and should prompt wider application of our analytical strategy in environmental matrices.
研究领域:
环境科学
·
毒理学
·
分析化学
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DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Chen-Xuan Li,Yun-Jie Wang,Chang-Bin Chen,Xian-Zhong Fu,Shuo Cui,Jia-Yuan Lu,Hou-Qi Liu,Wen-Wei Li
A non-radical reaction between peroxysulfates and phenolic compounds , as important structural moieties of natural organic matters, has been reported recently, implying new opportunities for environmental remediation without need for catalyst or energy input. However, this approach seems to be ineffective for halogenated aromatic compounds, an important disinfection by-products (DBPs). Here, we shed light on the interactions between peroxymonosulfate (PMS) and chlorophenols and the influential factors. The results show that the chlorophenols transformation kinetics were highly dependent on the solution pH and chlorophenol species: raising the pH significantly accelerated the chlorophenols degradation, and at alkaline pH the removal rates of different chlorophenols were in the order of trichlorophenol > dichlorophenol > chlorophenol > tetrachlorophenol. The faster degradation of pollutants with more chlorine groups was mainly due to their relatively higher dissociation degree, which favors a direct pollutant-PMS interaction to generate radicals for their degradation. The chlorophenol degradation intermediate (i.e. benzoquinone) further mediated the generation of singlet oxygen at alkaline pH, thereby contributing to accelerated pollutant removal . The slower degradation of tetrachlorophenol than other chlorophenols was likely due to its strong electrostatic epulsion to PMS which restricted the reaction. Our work unveils the chlorophenols degradation mechanisms in PMS reaction system, which may facilitate a better understanding and optimization of advanced oxidation processes for pollution control to reduce potential DBPs accumulation.
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
危险品化学品经营许可证（带存储）