ACS ES&T Water
·
2023
·
IF 5.3
Peizeng Yang,Jiayue Dong,Haiyan Wang,Teng Zhang,Gregory V. Korshin,Junhe Lu
N-Nitrosodimethylamine (NDMA) is a disinfection byproduct and a probable human carcinogen formed during water treatment processes. While its generation in engineered systems has been extensively explored, its formation in natural environments is inadequately understood. This study demonstrates that compounds with dimethylamine (DMA) functionality exposed to sunlight irradiation in the presence of nitrite (NO2–) react to form NDMA. The molar yields of NDMA ranged from 0.006 to 0.035% after 6 h irradiation. The radicals generated by the photolysis of NO2–, notably •OH, NO•, and NO2•, play critical roles in this process. Three reaction pathways are involved in the NDMA formation. In the first and second pathways, nitrogen oxide radicals couple or dimerize to form the nitrosating agents N2O3 and N2O4, which attack the DMA moiety, yielding NDMA. In the third pathway, the DMA moiety is oxidized by •OH via H-abstraction to produce a nitrogen-centered radical (CH3N•CH3) which, followed by the addition of a NO•, yields NDMA. Radical quenching experiments combined with theoretical calculations suggest that the •OH/H-abstraction pathway is more favorable. Given that many environmental contaminants contain DMA functionalities, the photochemical formation pathway of NDMA in the sunlit surface waters may be important for aquatic environments.
研究领域:
环境科学
·
公共卫生
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS
·
2022
·
IF 3.571
Gugu Hao,Rong Hu,Xiaoqin Wang,Pan Gao,Lin Wang,Manhua Jiang,Libo Xin,Guoying Tan,Yanping Zhao,Fuzhou Sun,Dexin Chu,Jinqian Lv,Jinsong You,Fangfang Huang,Xuezhi Song
In recent years, nitrosamines have been discovered in some types of drug products that becomes a current regulatory hotspot, and have attracted a lot attention from both regulatory authorities and industry. This manuscript provided an industry perspective on the nitrosamines research. A liquid chromatography coupled with tandem mass spectrometry（LC-MS/MS）method was developed and applied for the quantification of N-nitrosodimethylamine (NDMA) in metformin hydrochloride sustained-release tablets (MET). The key factors resulting in the NDMA formation in MET were identified through forced degradation and drug-excipient studies, which included high temperature, dimethylamine , strong alkali and oxidation conditions, peroxide and alkaline components contained in the formulation as well as the nitrite and nitrate impurities that might be presented in certain excipients. Further, API particle size and water content of the drug product would also affect the growth rate of NDMA. Therefore, the following mitigation strategies to reduce the risk of nitrosamines in the finished drug product are proposed in this manuscript: 1) avoid the use of excipients containing nitrite, nitrate and peroxide impurities; 2) avoid high temperature and strong alkaline environment in the production and storage condition; 3) maintain an appropriate water content level in the formulation. Based on the above principles, it was recommended to add antioxidant or incorporate excipient such as Na 2 CO 3 to modify the formulation pH to weak basic environment in the formulation of MET, which can could effectively prevent formation of NDMA in the stability process.
研究领域:
药学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Haiyan Wang,Peizeng Yang,Yiqian Song,Deyang Kong,Junhe Lu
UV-based treatment technologies have been widely applied in wastewater treatment plants due to its high efficiency in deactivating pathogens and degrading organic contaminants. However, this study demonstrates that N -nitrosodimethylamine (NDMA), a probable human carcinogen, can be generated during UV treatment of dimethylamine (DMA) pollutants of concern, for example isoproturon (IPU), in the presence of nitrite (NO 2 – ). Quenching tests have identified that in addition to direct photolysis, hydroxyl radicals (HO • ) and nitrogen oxide radicals (NO • and NO 2 • ) generated from NO 2 – photolysis play a crucial role in the reaction. They can react with IPU, leading to hydroxylated and nitrated products. More importantly, NO 2 • couples with a NO • or another NO 2 • to form N 2 O 3 and N 2 O 4 , respectively. As nitrosating agents, N 2 O 3 and N 2 O 4 directly attack the released DMA during IPU degradation, yielding NDMA. At IPU initial concentration of 50 μM, the highest concentration of NDMA was 5.62 μg/L in 2.5 h by UV/NO 2 – , corresponding to the molar yield of 0.22%. This study further reveals that other dimethylamine compounds, such as diuron, imipramine, and tetracyclines, can also serve as NDMA precursors during UV disinfection with NO 2 – present. Given that many environmental contaminants contain DMA moieties and NO 2 – is ubiquitously present in wastewaters, formation of NDMA during UV disinfection is probably a common but overlooked problem, which deserves emerging concern.
研究领域:
环境科学
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水处理
·
化学工程
·
毒理学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Kai Gao,Qing Wang,Xuexun Du,Qinglian Wei,Yongmin Huang
Dimethylamine (DMA), which is mostly generated in fine chemical industry, has enormously threatened the public health, therefore should be eliminated from water efficiently. Superior to any other methods to remove DMA, adsorbing it by sorbent could avoid the generation of secondary pollution. Among all the sorbents employed in this study, low Si/Al ratio Beta zeolite synthesized without organic template exhibits the highest performance of adsorbing DMA from water. When the transition-metal cations were introduced by ion-exchange, the adsorption of DMA was enhanced. Subsequently, the saturated adsorbent was heated in air condition, detection results of the off-gas indicated that nearly all of the DMA adsorbed was oxidized and negligible harmful by-product was produced. Beta zeolite adsorption coupled with catalytic oxidation could eliminate DMA efficiently and environmental friendly which has wide application prospects in waterworks.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2018
·
IF 6.653
Ying Han,Jihe Wang,Jun Li,Zhonglin Chen,Weiwei Li,Beibei Jiang,Jie Yao
Copper corrosion products (Cu(OH)2, Cu2O, CuO and Cu2CO3(OH)2) were applied to catalyze the reduction of N-Nitrosodimethylamine (NDMA) with iron. All the copper corrosion products showed catalytic abilities. Lower pH values and DO concentrations facilitated NDMA reduction in most cases. 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine, UDMH) and dimethylamine (DMA) formed during the degradation of NDMA. There were also some undetected products. Catalytic hydrogenation was proposed as the mechanism. The catalytic systems did not promote the formation of hydrogen atoms. The dissolved copper ions in these systems were too sparse to enhance the reaction. The smooth iron surface and formation of Cu2O in each catalytic system explained the enhancement of NDMA removal. Different surface morphologies and states of Cu2O accounted for the differences in NDMA removal and kinetics between the reaction systems. This technique could be an alternative for NDMA reduction and could broaden the application of copper corrosion products.
研究领域:
环境科学
·
化学工程
·
水处理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Ying Han,Xiaoping Zheng,Beibei Jiang,Yuling Tang,Hongyuan Liu,Kemin Zhang,Yaping Guo,Jun Li
The influencing factors, products and mechanism of N -nitrosodimethylamine (NDMA) reduction by zinc (Zn) in the presence of transition-metal ions (Mn 2+ , Co 2+ and Ni 2+ ), were investigated. The NDMA removal by Zn was significantly improved by them, and the promoting effect of Co 2+ and Ni 2+ were better than Mn 2+ . With the decrease of pH values and dissolved oxygen concentrations, the removals of NDMA were enhanced in all reaction systems. NDMA was mainly reduced to unsymmetrical dimethylhydrazine (UDMH) in Zn and Zn/Mn 2+ systems. It was mainly reduced to dimethylamine (DMA) and ammonium (NH 4 + ) in Zn/Co 2+ and Zn/Ni 2+ systems. There were undetected products in all reaction systems. Catalytic hydrogenation was the main mechanism, and active hydrogen atom was the main active species. The presence of Mn 2+ , Co 2+ and Ni 2+ promoted the corrosion of Zn and changed the surface morphology of Zn. The formation of type I film on Zn surface was promoted in the presence of Co 2+ and Ni 2+ , which was conducive to the continuous corrosion of Zn and hydrogen generation. While type II film which would inhibit the corrosion of Zn formed on Zn surface in the presence of Mn 2+ . MnO 2 , Co 3 O 4 and Ni(OH) 2 were formed in Zn/Mn 2+ , Zn/Co 2+ and Zn/Ni 2+ systems, respectively. They would facilitate more generation of active hydrogen atoms.
研究领域:
环境化学
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水处理
·
催化
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2016
·
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
·
催化
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2024
·
IF 5.9
Hailan Wang,Fu Gu,Xiulian Ren,Qifeng Wei
The utilization of algal ingredients for producing functional products has garnered significant attention. Furthermore, increasing the yield of polysaccharides has become a crucial point. In this work, the efficiencies of two-step extraction and co-extraction were compared, and dimethylamine solution was selected as the optimal extractant. Under the optimum extraction conditions (temperature of 75.00 °C, time of 3.15 h, liquid-solid ratio of 35.00 mL/g) determined by response surface methodology, the yield of alginate was 16.05 ± 0.37 % and the yield of fucoidan was 2.85 ± 0.08 %. Kinetic analysis of the extraction process was conducted using the shrinking core model, elucidating the rate and mechanism of product release. Additionally, it was demonstrated that the dimethylamine solution could be recycled for five times with stable extraction performance. The extraction mechanism was further analyzed by quantum chemical calculations, providing theoretical support for the extraction process of the products. The above results demonstrated that the higher yield of products extracted with dimethylamine was confirmed through experimental and quantum chemical analysis. Overall, this study provides a new perspective on the extraction of alginate and fucoidan from seaweed.
研究领域:
海洋生物学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Peizeng Yang,Hailing Chu,Jiating Liu,Teng Zhang,Junhe Lu
Sulfate radical (SO 4 •− ) advanced oxidation processes (SR-AOPs) are efficient for degrading a broad spectrum of contaminants. This study demonstrates that the existence of environmentally relevant concentrations of nitrite (NO 2 − ) can lead to the formation of N -nitrosodimethylamine (NDMA), a probable human carcinogen, when heat activated peroxydisulfate (heat/PDS) is applied to address contaminants with dimethylamine moieties, such as tetracyclines. NO 2 − effectively competes with tetracyclines for SO 4 •− at a high second-order reaction rate constant of 8.8 × 10 8 M −1 s −1 , thus suppressing the degradation. Simultaneously, SO 4 •− reacts with NO 2 − to form the nitrogen dioxide radical (NO 2 • ) which rapidly dimerizes to a potent nitrosating agent named dinitrogen tetroxide (N 2 O 4 ). N 2 O 4 , in turn, attacks the dimethylamine moiety in tetracyclines via nucleophilic substitution, contributing to the degradation of parent compounds and generating an active intermediate that quickly decomposes to NDMA, along with the release of R + and NO 3 − . The released R + can be further oxidized by SO 4 •− to form phenolic intermediates which combine with NO 2 • to generate nitrated products. When 5 μM oxytetracycline (OTC) was treated with 0.5 mM PDS in the presence of 20 μM NO 2 − at 60 °C, the highest formation of NDMA was 0.045 μM in 1 h. NDMA formation was also observed for other compounds with dimethylamine moieties, such as methylene blue, phenylurea herbicides, etc., with the molar yield ranging from 0.07 to 3.53 %, negatively related to the R-N bond dissociation energy of the precursors. These findings suggest that NDMA can be commonly generated when SO 4 •− is applied to the degradation of dimethylamine pollutants in wastewater treatment or groundwater remediation where NO 2 − ubiquitously exists, which may pose a serious threat to the aquatic environment.
研究领域:
环境科学
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Cleaner Production
·
2017
·
IF 5.715
Yuanan Hu,Yuanzhen He,Hefa Cheng
N -nitrosodimethylamine (NDMA), a highly toxic and carcinogenic disinfection byproduct , cannot be efficiently removed by conventional water treatment processes , while sorption by microporous minerals, followed by destruction with microwave irradiation has been developed as a promising alternative. This work examined the impact of surface cation density and type on sorption of NDMA on dealuminated ZSM-5 zeolites , and on microwave-induced degradation of the sorbed NDMA, as well as the non-thermal effect of microwave. NDMA sorption was found to increase with the framework Si/Al ratio of dealuminated ZSM-5 zeolites (i.e., decreasing density of surface cations), and was also influenced by the type of surface cations. Degradation of the sorbed NDMA proceeded faster with increases in the power level of microwave and in the micropores with higher densities of surface cations, which was attributed to the increases in the number and/or temperature of micro-scale “hot spots” formed by microwave dielectric superheating of the surface cations. The degradation rate of sorbed NDMA was also found to be inversely correlated with the hydration free energy of surface cations present in the zeolite micropores . The apparent activation energy estimated from the temperature dependence of NDMA degradation in the micropores under microwave irradiation was 18.2 kJ/mol, which is much lower than those of typical thermolysis reactions and is indicative of significant contribution from the non-thermal effect of microwave.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2020
·Vol. 10
·期 8
·1612
·
IF 4.324
Zhaoyu Wen,Qiong Fu,Jie Wu,Guangyin Fan
Simple and efficient synthesis of a nano-catalyst with an excellent catalytic property for hydrogen generation from hydrolysis of dimethyl amine-borane (DMAB) is a missing piece. Herein, effective and recycled palladium (Pd) nanoparticles (NPs) supported on soft nitriding porous carbon (NPC) are fabricated and applied for DMAB hydrolysis. It is discovered that the soft nitriding via a low-temperature urea-pretreatment induces abundant nitrogen-containing species on the NPC support, thus promoting the affinity of the Pd precursor and hindering the agglomeration of formed Pd NPs onto the NPC surface during the preparation process. Surface-clean Pd NPs with a diameter of sub-2.0 nm deposited on the NPC support (Pd/NPC) exhibit an outstanding catalytic performance with a turnover frequency (TOF) of 2758 h−1toward DMAB hydrolysis, better than many previous reported Pd-based catalysts. It should be emphasized that the Pd/NPC also possesses a good stability without an obvious decrease in catalytic activity for DMAB hydrolysis in five successive recycling runs. This study provides a facile but efficient way for preparing high-performance Pd catalysts for catalytic hydrogen productions.Keywords:nano-catalyst;dimethyl amine-borane;palladium nanoparticles;hydrolysis;soft nitriding
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DESALINATION
·
2014
·
IF 3.96
Shenglei Sun,Zhonglian Yang,Xin Huang,Fan Bu,Defang Ma,Hongyu Dong,Baoyu Gao,Qinyan Yue,Yan Wang,Qian Li
Polyferric chloride (PFC) and epichlorohydrin–dimethylamine (DAM–ECH) with different PFC (as Fe 3 + )/DAM–ECH mass ratios (MR) and dose methods were used in the treatment of humic acid–kaolin (HA–kaolin) simulated water under different pH conditions. Coagulation performance, floc characteristics and membrane fouling of PFC/DAM–ECH in coagulation–ultrafiltration (C–UF) process were investigated in this study. Results showed that the optimum coagulation performance was achieved when PFC dose was 15 mg/L with PFC/DAM–ECH MR of 2:1 under pH 6.0. Opposite adding sequence (DAM–ECH/PFC) would reduce UV 254 (ultraviolet adsorption at 254 nm) and DOC (dissolved organic carbon) removal efficiency. Addition of DAM–ECH on the basis of PFC produced larger and stronger flocs with better regrowth ability. Proper dosage of DAM–ECH under certain coagulation condition could achieve the best coagulation performance and keep the UF membrane operating under a preferable status. Results of this study would be beneficial for application of composite coagulant PFC–DAM–ECH and DAM–ECH as coagulant aid in water treatment processes.
研究领域:
环境科学
·
水处理工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）