Fabrication of TiO2/γ-CD films for nitro aromatic compounds and its sensing application via cyclic surface-polarization impedance (cSPI) spectroscopy

2007 ◽  
Vol 123 (1) ◽  
pp. 359-367 ◽  
Author(s):  
Myung-Jong Ju ◽  
Do-Hyeon Yang ◽  
Seung-Woo Lee ◽  
Toyoki Kunitake ◽  
Kenshi Hayashi ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Surface Polarization ◽  
Polarization Impedance ◽  
Sensing Application ◽  
Cyclic Surface ◽  
Nitro Aromatic

scholarly journals The formation of nitro-aromatic compounds under high NO<sub><i>x</i></sub> and anthropogenic VOC conditions in urban Beijing, China

2019 ◽  
Vol 19 (11) ◽  
pp. 7649-7665 ◽  
Author(s):  
Yujue Wang ◽  
Min Hu ◽  
Yuchen Wang ◽  
Jing Zheng ◽  
Dongjie Shang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Aromatic Compounds ◽  
Total Concentration ◽  
Fine Particulate Matter ◽  
Oxidation Products ◽  
Urban Atmosphere ◽  
Formation Pathway ◽  
Relative Contribution ◽  
Phase Oxidation ◽  
Nitro Aromatic

Abstract. Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-NOx and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., NO2, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63 ng m−3, higher than those reported in other summertime studies (0.14–6.44 ng m−3). 4-Nitrophenol (4NP, 32.4 %) and 4-nitrocatechol (4NC, 28.5 %) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of NOx was found to be a more dominant source of NACs than primary biomass burning emissions. The NO2 concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-NOx regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were NO2 ∼ 20 ppb for daytime and NO2∼25 ppb for nighttime conditions. Under low-NOx conditions, NACs increased with NO2, while the NO3- concentrations and (NO3-)/NACs ratios were lower, implying organic-dominated products. Under high-NOx conditions, NAC concentrations did not further increase with NO2, while the NO3- concentrations and (NO3-)/NACs ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of NO2 could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC+4M5NC) ∕ 4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH > 30 %. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.

Highly fluorescent scandium-tetracarboxylate frameworks: selective detection of nitro-aromatic compounds, sensing mechanism, and their application

2020 ◽  
Vol 49 (48) ◽  
pp. 17737-17744
Author(s):  
Deyi Zhan ◽  
Abdul Saeed ◽  
Zixuan Li ◽  
Chengming Wang ◽  
Zhiwu Yu ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Metal Organic Frameworks ◽  
Selective Detection ◽  
Sensing Mechanism ◽  
Metal Organic ◽  
Nitro Aromatic

Recently, exploring new luminescent metal–organic frameworks (LMOFs) to selectively detect nitro-aromatic compounds (NACs) has been a hot topic of research.

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