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Photochemical Smog
Published in Stanley E. Manahan, Environmental Chemistry, 2022
It is likely that NO3 levels become high enough in the hour before sunset to begin to have an effect on tropospheric chemistry. At night, the levels of NO3 become much higher, typically reaching values of around 8 × 107 molecules/cm3 compared to only approximately 1 × 106 molecules/cm3 for hydroxyl radical. Although the hydroxyl radical reacts 10–1,000 times faster than NO3 , the much higher concentration of the latter means that it is responsible for much of the atmospheric chemistry that occurs at night. The nitrate radical adds across the double bonds in alkenes leading to the formation of reactive radical species that participate in smog formation.
Photochemical Smog
Published in Stanley Manahan, Environmental Chemistry, 2017
It is likely that NO3 levels become high enough in the hour before sunset to begin to have an effect on tropospheric chemistry. At night, the levels of NO3 become much higher, typically reaching values of around 8 × 107 molecules/cm3 compared to only approximately 1 × 106 molecules/cm3 for hydroxyl radical. Although the hydroxyl radical reacts 10 to 1000 times faster than NO3, the much higher concentration of the latter means that it is responsible for much of the atmospheric chemistry that occurs at night. The nitrate radical adds across the double bonds in alkenes leading to the formation of reactive radical species that participate in smog formation.
Eco-friendly oxidation of a reactive textile dye by CaO2: effects of specific independent parameters
Published in Environmental Technology, 2023
In textile production, nitrate (NO3−) compounds are used as auxiliary chemicals, and nitrate is transferred to wastewater from the dyeing and printing stages [79]. NaNO3 was used as the NO3− source in RB5 oxidation experiments. The experiments have shown that the NO3− has the lowest inhibitory effect among the tested anions (Figure 15). The RB5 removal efficiencies with the presence of 1600 mg/L and 2000mg/L NO3− were calculated as 77.7% and 70.9%, respectively. The decrease in RB5 oxidation in the presence of NO3− can be explained by the nitrate radical (•NO3) formed from the reaction of the •OH radical and the NO3− anion (Eq20). The •NO3 radical has a lower oxidation potential than the •OH radical [84]. The oxidation–reduction potential of nitrate radicals (2.3 ∼ 2.5 V) is slightly lower than hydroxyl radicals. Also, the oxidising capacity of nitrate radicals is higher than some reactive species, such as superoxide radicals. This may explain the low negative effect of nitrate presence on oxidation efficiency of RB5 by CaO2 [83, 85].
Aluminium(III) Salophen complex as a luminescent turn-off/turn-on sensor for nitrobenzene, Fe3+, and toluene
Published in Journal of Coordination Chemistry, 2023
Yu-Heng Zhang, Xiao-Yong Zhang, Sheng-Li Yong, Xue-Lin Ma, Jun-Fang Gao, Qian-Nan Jia, Yu Long Zhao, Yan Chen
The XPS analysis also confirms the structure of Salp-Al (Figure 5), whose Al2p, C1s, N1s, and O1s peaks are at 74, 285, 396, and 532 eV, respectively (Figure 5(b)). Elemental analysis reveals that the C, H, and N content of Salp-Al is 54.37%, 4.57%, and 9.33%. It is apparent that the N1s (figure 5(c, d)) and O1s (Figure 5(e, f)) peaks of Salp-Al primarily come from the N and O atoms of Salp, water, and nitrate radical [36–38], respectively. In contrast, after the Al(NO3)3 treatment of Salp, the new peaks at 399.90 eV and 403.03 eV in the N1s XPS spectrum are assigned to –N–Al (Figure 5(d)) and the new peaks at 532.52 eV in the O1s XPS spectrum are assigned to –O–Al (Figure 5(f)). The binding energy of C1s from Salp and Salp-Al has almost no change, implying that C does not interact with the Al3+ ions (Figure S9). The result suggests weak coordination of Al3+ to the N and O on Salp, nitrate radical, and water. The preceding analysis agrees well with the NMR results and fully confirms the structure of Salp-Al.
Ab initio studies on the NO(X2II) − O2(X3 Σg−) van der Waals complexes in the doublet state
Published in Molecular Physics, 2020
The nitric oxide radical NO is involved in many industrial and biological processes. It is a cardiovascular signalling molecule and participates in the regulation of blood pressure, among many other functions [1]. The mechanism of the auto-oxidation of NO to nitrogen dioxide NO2 has received considerable attention [2]. Auto-oxidation in tissues may prevent NO from reaching its targets [3]. It is believed to be a two-step process, with ONOO or N2O2 being the intermediate [4]. Bhatia and Hall [5], using matrix isolation infrared spectroscopy, found evidence for a stable trans peroxo nitrate radical ONOO. While theoretical work by Eisfeld and Morokuma [6], based on coupled cluster and multiconfiguration interaction methods, concluded that ONOO does not have a bound doublet structure, later work by Dutta et al. [7], using multireference coupled-cluster methods, found that ONOO is stable, having a trans structure. Their calculated infrared spectrum was in good agreement with that of Bhatia and Hall [5]. Experimental studies of the auto-oxidation of NO by Mahmoudi et al. [4], using low-temperature trapping of intermediates, also found evidence for the existence of ONOO, suggesting that the auto-oxidation of NO proceeds via ONOO as intermediate. Gas-phase EPR spectroscopy of NO/O2 mixtures by Galliker et al. [8] discovered both ONOO and ONOONO as intermediates in the auto-oxidation of NO.