Addition Of NO Research Articles

Development of Nitrolactonization Mediated by Iron(III) Nitrate Nonahydrate

The nitrolactonization of alkenyl carboxylic acids mediated by Fe(NO3)3·9H2O has been developed. Nitrolactones were obtained in up to 93% yield by treatment of alkenyl carboxylic acids with Fe(NO3)3·9H2O. Mechanistic studies disclosed that the reaction proceeded through a radical intermediate generated from addition of NO2 to alkenyl carboxylic acids.

Reaction Kinetics of Nitric Oxide on Size-Selected Silver Cluster Cations

We report reactions of gas-phase free silver cluster cations, Agn+ (n = 3–18), with nitric oxide molecules, which was studied by kinetics measurements using an ion trap. AgnO(NO2)m−1+ and Agn(NO2)m+ were observed as major products after multiple reactions. The reaction pathway to form these product ions was identified by fitting the data to rate equations for n ≤ 15, except for inert n = 3 and 5. Two different reaction mechanisms were found for the formation of these products depending on cluster size; pseudo-first-order rate constants of each step of elementary reactions were obtained. First, as found for n = 4, 6, and 9, AgnO+ is formed by a reaction with two NO molecules, which is followed by a release of neutral N2O. A further reaction of AgnO+ with another NO molecule produces AgnNO2+. Agn(NO2)m+ (m ≥ 1) is thus successively formed via an intermediate, AgnO(NO2)m−1+. This is analogous to the reaction of NO on silver surfaces to produce NO2. Second, both AgnNO2+ and AgnO+ are formed concurrently, as found for n = 7, 8, 10, 11, 12, and 15; AgnO+ does not act as an intermediate for AgnNO2+. AgnO(NO2)m−1+ and Agn(NO2)m+ (m ≥ 2) are formed by successive addition of NO2 to AgnO+ and AgnNO2+, respectively. It is speculated that the successive addition of NO2 proceeds via disproportionation, i.e., three NO molecules are converted to NO2 and N2O. The reaction pathways of n = 13 and 14 are explained equally well by the two mechanisms. The overall reaction rate coefficients exhibit an odd–even alternation; the higher reactivity for even values of n is due to an odd number of valence electrons.

Mechanistic insight into the degradation of ibuprofen in UV/H2O2 process via a combined experimental and DFT study

The study investigated the degradation kinetic and transformation mechanism of ibuprofen (IBP) in UV/H2O2 process from both experimental and theoretical aspects. Impacts of H2O2 dosage, solution pH, quenching agent, and concentration of nitrite (NO2−) on IBP degradation in UV/H2O2 process were evaluated. Both experimental results and theoretical calculations indicated that •OH played an important role in the degradation of IBP and its transformation products. The second-order rate constants of •OH and •NO2 with IBP were calculated as 3.93 × 109 M−1 s−1 and 5.59 × 10−3 M−1 s−1, based on the transition state theory, which explained the phenomenon that addition of NO2− inhibited IBP degradation. Further, according to the results of ultra-high-resolution mass and density functional theory calculations, mechanisms of a detailed degradation pathway for IBP were clarified. Namely, the detailed mechanistic formation pathways for hydroxylated and keto-based products were proposed. Then, possible active sites of the keto-based products, as well as the corresponding subsequent products were predicted by Condensed Fukui Function. Our study can broaden the knowledge of the reactions of emerging contaminants with •OH, and provide theoretical foundation for the optimization of UV/H2O2 process.

Reaction of NO2 with Groups IV and VI Transition Metal Oxide Clusters.

The addition of NO2 to Group IV (MO2)n and Group VI (MO3)n (n = 1-3) nanoclusters was studied using both density functional theory (DFT) and coupled cluster theory (CCSD(T)). The structures and overall binding energetics were predicted for Lewis acid-base addition without transfer of spin (a physisorption-type process) and the formation of either cluster-ONO (HONO-like or bidentate bonding) or NO3- formation where for both the spin is transferred to the metal oxide clusters (a chemisorption-type process). Only chemisorption of NO2 is predicted to be thermodynamically allowed at temperatures ≥298 K for Group IV (MO2)n clusters with the formation of surface chemisorbed NO2 being by far the most energetically favorable. The ligand binding energies (LBEs) for physisorption and chemisorption on the TiO2 nanoclusters are consistent with computational studies of the bulk solids. Chemisorption is only predicted to occur for (CrO3)n clusters in the form of a terminal nitrate containing species whereas the larger chemisorbed nitrate structures for (MoO3)n and (WO3)n were found to be metastable and unlikely to form in any appreciable amount at temperatures of 298 K and higher. NO2 is predicted to only be capable of physisorbing to (MoO3)n and (WO3)n at lower temperatures and therefore unlikely to bind NO2 at temperatures ≥298 K. Correlations between the (MO3)nNO2 ligand bond energies and the chemical properties of the parent (MO3)n clusters (Lewis acidity, ionization potentials, excitation energies, and M = O/M-O bond strengths) are described.

Homogeneous conversion of NOx and NH3 with CH4, CO, and C2H4 at the diluted conditions of exhaust‐gases of lean operated natural gas engines

AbstractUnderstanding gas‐phase reactions in model gas mixtures approximating pre‐turbine heavy‐duty natural gas engine exhaust compositions containing NO, NH3, NO2, CH4, CO, and C2H4 is extremely relevant for aftertreatment procedure and catalyst design and is thus addressed in this work. In a plug‐flow reactor at atmospheric pressure, five different model gas mixtures were investigated in the temperature range of 700‐1 200 K, using species analysis with electron ionization molecular‐beam mass spectrometry. The mixtures were designed to reveal influences of individual components by adding NO2, CH4, CO, and C2H4 sequentially to a highly argon‐diluted NO/NH3 base mixture. Effects of all components on the reactivity for NOx conversion were investigated both experimentally as well as by comparison with three selected kinetic models. Main results show a significantly increased reactivity upon NO2 and hydrocarbon addition with lowered NO conversion temperatures by up to 200 K. Methane was seen to be of dominant influence in the carbon‐containing mixtures regarding interactions between the carbon and nitrogen chemistry as well as formaldehyde formation. The three tested mechanisms were capable to overall represent the reaction behavior satisfactorily. On this basis, it can be stated that significant gas‐phase reactivity was observed among typical constituents of pre‐turbine natural gas engine exhaust at moderate temperature.

Monitoring of Nitrification in Chloraminated Drinking Water Distribution Systems With Microbiome Bioindicators Using Supervised Machine Learning.

Many drinking water utilities in the United States using chloramine as disinfectant treatment in their drinking water distribution systems (DWDS) have experienced nitrification episodes, which detrimentally impact the water quality. Identification of potential predictors of nitrification in DWDS may be used to optimize current nitrification monitoring plans and ultimately helps to safeguard drinking water and public health. In this study, we explored the water microbiome from a chloraminated DWDS simulator operated through successive operational schemes of stable and nitrification events and utilized the 16S rRNA gene dataset to generate high-resolution taxonomic profiles for bioindicator discovery. Analysis of the microbiome revealed both an enrichment and depletion of various bacterial populations associated with nitrification. A supervised machine learning approach (naïve Bayes classifier) trained with bioindicator profiles (membership and structure) were used to classify water samples. Performance of each model was examined using the area under the curve (AUC) from the receiver-operating characteristic (ROC) and precision-recall (PR) curves. The ROC- and PR-AUC gradually increased to 0.778 and 0.775 when genus-level membership (i.e., presence and absence) was used in the model and increased significantly using structure (i.e., distribution) dataset (AUCs = 1.000, p < 0.01). Community structure significantly improved the predictive ability of the model beyond that of membership only regardless of the type of data (sequence- or taxonomy-based model) we used to represent the microbiome. In comparison, an ATP-based model (bulk biomass) generated a lower AUCs of 0.477 and 0.553 (ROC and PR, respectively), which is equivalent to a random classification. A combination of eight bioindicators was able to correctly classify 85% of instances (nitrification or stable events) with an AUC of 0.825 (sensitivity: 0.729, specificity: 0.894) on a full-scale DWDS test set. Abiotic-based model using total Chlorine/NH2Cl and NH3 generated AUCs of 0.740 and 0.861 (ROC and PR, respectively), corresponding to a sensitivity of 0.250 and a specificity of 0.957. The AUCs increased to > 0.946 with the addition of NO2– concentration, which is indicative of nitrification in the DWDS. This research provides evidence of the feasibility of using bioindicators to predict operational failures in the system (e.g., nitrification).

Effect of nitrogen dioxide addition on ethane auto-ignition at different pressures and equivalence ratios: Experiments and chemical kinetic modeling

Ignition delay times of C2H6/O2/Ar mixtures with NO2 concentration changing from 0 to 2100 ppm were measured at T = 772–980 K, φ = 0.5–2.0 and p = 15–30 bar in a rapid compression machine. In general, the results show that NO2 addition significantly promotes ethane ignition and reduces its global activation energy. And NO2 promoting effect is more remarkable at fuel-lean and low-pressure condition at given NO2 concentration. The results also demonstrate that pressure shows smaller effect on the ignition of mixtures doped with NO2 than those on neat ethane ignition. Three literature NOx models are selected to validate against the new measured data set to evaluate their performances. Finally, sensitivity and flux analyses are conducted to identify the key reaction classes controlling the ignition of C2H6-NO2 mixtures.

Effects of common inorganic anions on the ozonation of polychlorinated diphenyl sulfides on silica gel: Kinetics, mechanisms, and theoretical calculations

In this work, the ozonation properties of 2,2′,3′,4,5-pentachlorodiphenyl sulfide (PeCDPS) was systematically studied, with special emphasis on the underlying mechanism for the effects of inorganic ions. Kinetic experiments show that common ions can significantly reduce the oxidative properties of ozone, except for SO32− and Cu2+. The inhibition effect of anions has been explained through the scavenging effect of free radicals and the generation of other free radicals with weaker oxidation potentials, but no research has reported on the effect of free radicals generated by anions on the degradation pathway. However, SO32− and Cu2+ exerted a promoting effect through enhanced formation of ·OH via the hydrolysis effect and the catalyzed decomposition of O3, respectively. According to the intermediate products identified by high performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) analysis, direct oxidation of S atom, substitution of Cl atom with -OH group, and hydroxylation of the benzene ring were commonly observed. The addition of NO2− and SO32- produced new free radicals like ·NO2, ·SO3 and ·SO4−, which would attack the parent compound or its primary product, thus influencing the degradation efficiency and pathways. The radicals initiated reactions and the structures of the corresponding products were further rationalized by density functional theory (DFT) calculations. These findings provide new insights into the effects of common anions on ozone oxidation of organic compounds.

Radiolytic degradation of ornidazole in aqueous solutions by electron beam irradiation: Implications to parameters, kinetics, toxicity and cost evaluation

The study is aimed to assess the effectiveness of electron beam (EB) technology to degrade the antibiotic ornidazole (ORN) in aqueous solution. The influence of several factors viz. initial ORN concentrations, dose, pH of solution, and addition of NO2−, NO3−, isopropanol, H2O2, thiourea, and different water mediums were evaluated on the ORN degradation. The degradation of ORN was followed by pseudo first-order reaction kinetics with rate constant value of 2.01, 1.17, 0.87 and 0.70 kGy−1 for the initial concentrations of 25, 50, 75, and 100 mg L−1 with their corresponding (G-(ORN)) values of 0.93, 1.60, 1.97, and 2.12 μmol J−1, respectively. The presence of NO2−, thiourea and isopropanol revealed reduction in the k-value, whereas, addition of NO3− anion had not substantially effected the degradation of ORN. Presence of H2O2 exhibits significant effect on the mineralization efficiency of ORN rather than degradation extent. The efficacy of EB irradiation to degrade ORN decreased in wastewater in comparison to surface, ground and ultrapure water. Based on the LC-QTOF-MS study, it could be ascribed that degradation of ORN was primarily due to the oxidative species HO radical and direct cleavage of ORN compound. Tentative pathways for EB-induced radiolytic degradation of ORN were proposed. Cytotoxicity assessment and overall cost of electrical energy consumed for the degradation of ORN was also evaluated.

2 + 2 + 1] Heteroannulation of Alkenes with Enynyl Benziodoxolones and Silver Nitrite Involving C≡C bond Oxidative Cleavage: Entry to 3-Aryl-Δ2-isoxazolines.

A copper-catalyzed [2 + 2 + 1] heteroannulation of alkenes with enynyl benziodoxolones and AgNO2 involving oxidative cleavage of the C≡C bond promoted by cooperative Zn(OTf)2, KOAc, and 4 Å MS for producing 3-aryl Δ2-isoxazolines is reported. Mechanistic studies indicate that AgNO2 serves as the N/O two-atom unit source, enabling the formation of three bonds through NO2 addition across the C≡C bond, NO-transfer, C≡C bond cleavage, and annulation cascades.

Influence of Humidity on a Resistive Room Temperature NO2 Dosimeter Based on Al-Doped ZnO

Introduction ZnO is well suited to detect harmful gases such as NO2 at room temperature. The behavior of ZnO as a resistive concentration sensor with fast response and decay is investigated in many studies [1]. In this work, ZnO is used as a resistive NO2 dosimeter at room temperature as shown in [2]. The sensor shows accumulative behavior so that the NO2 dose, which is proportional to the time integral of the NO2 concentration, can be determined directly. This means that the dose can be determined without often error-prone (especially for small concentrations) mathematical integration of the concentration signal. In contrast to other accumulating sensors, a time-resolved sensor signal can be obtained by mathematical derivation.Two operation phases exist for a resistive gas dosimeter, the sorption phase and the regeneration phase [2]. In the sorption phase, analyte (here: NO2) is sorbed at the functional layer (here: ZnO with 3 % Al), leading to an electrical conductivity change of the sensor layer. In absence of the analyte, the sensor signal remains constant, meaning that there is no desorption of the previously sorbed gas species. If all sorption sites are occupied, the analyte is specifically desorbed (e.g. thermally, chemically or by UV exposure [2]) in the regeneration phase before a new measuring cycle can begin. In this study for regeneration UV light (385 nm) is used to guarantee the room temperature operation of the dosimeter. Since it is known that humidity may affect the sensor signal and may promote desorption of adsorbed gas molecules [3], it will be investigated to what extent the dosimeter signal changes due to the influence of humidity. Methods and Materials Al-doped ZnO was produced by sol-gel synthesis as published in [4]. The functional layers were deposited on substrates with gold interdigital electrodes. The sensors were exposed to NO2 in the ppb range in dry and humid (17. 9 % r.h., 44.9 % r.h., 89.8 % r.h.) synthetic air and an impedance measurement was used to characterize the sensor behavior. Further, a water film was created by dropping water onto the sensor to check how a water film on the sensor surface affects the sensor impedance. Results and Conclusion In Fig. 1, the Nyquist plot (U eff = 100 mV, f = 10 MHz -1 Hz) of the sensor for different humidity levels and for a sensor with a water film at room temperature is shown. One can see that from dry air up to 44.9 % r.h. there is a semicircle, which indicates an R||C equivalent circuit. Here, the resistance R can be calculated by eq. 1, where |Z| is the absolute value of the impedance and φ is the phase. The higher the humidity content is, the lower is the resistance, as expected. For higher humidity levels and the sample with the water film, no semicircle is found. Consequently, it is no longer possible to calculate R by eq. 1. The Nyquist plot measured in 89.9 % r.h. is similar to the one of the sensor with a water film. It can therefore be assumed that a closed water film forms on the sensor surface above a certain humidity, that dominates the electrical behavior and no dosimeter sensor signal is measurable anymore. In Fig. 2, the NO2 sensor signal is shown for dry air, 17.9 % r.h., and 44.9 % r.h., respectively. For dry air, dosimeter-type behavior can be observed. A linear correlation between sensor signal (R- R 0)/R 0 and dose D can be expected. In humidity, the sensor signal does not remain constant after NO2 exposure, but decreases a little. This means that a part of the previously adsorbed NO2 is desorbed. It is assumed, that adsorbed water molecules thus promote desorption of the adsorbed NO2, which leads to the observed loss of the dosimeter behavior. When UV light is turned on for regeneration at t = 100 min, one can see that in dry air the resistance decreases slower than in humid air. This again is a sign for a faster desorption of oxygen and NO2 in humid air. The dosimeter signal is therefore strongly affected by humidity, because desorption of adsorbed species is favored under humidity.So it is important to find a way to reduce the influence of humidity for room temperature detection of ppb level NO2. As the desorption of NO2 at 17.9 % r.h. and 44.9 % r.h. is not so pronounced that the sensor signal returns to zero after NO2 addition, it may be assumed that the dosimeter behavior is maintained up to a certain humidity content. Since it is intended to use such a sensor without heating, the influence of humidity must also be investigated at temperatures around room temperature.

A colorimetric fluorescent probe for rapid and specific detection of nitrite.

The method of fluorescent probes has been an important technique for detection of nitrite (NO2 - ). As an important inorganic salt, excessive nitrite would threaten humans and the environment. In this paper, a colorimetric fluorescent probe P-N (1,2-diaminoanthraquinone) with rapid response and high selectivity, which could detect NO2 - by visual colour changes and fluorescence spectroscopy is presented. The probe P-N solution (pH 1) changed from pink to colourless with the addition of NO2 - and fluorescence intensity at 639nm clearly decreased. Good linear exists between fluorescence intensities and NO2 - concentrations for the range 0-16μM, and the detection limit was 54nM (based on a 3σ/slope). Moreover, probe P-N could also detect NO2 - in real water samples, and results were all satisfactory. Probe P-N shows great practical application value for detecting NO2 - in the environment.

Intrinsically ESIPT-exhibiting and enhanced emission in polymer nanoparticles as signaling for sensing nitrite.

A straightforward approach to the fabrication of intrinsically excited-state intramolecular proton transfer (ESIPT)-fluorescent polymer nanoparticles (e-PNPs) was developed. The e-PNPs were obtained by self-assembly of the homopolymers derived from 4-aminosalicylic acid in aqueous solution. By incorporating ESIPT modules into polymer nanoparticles, the ESIPT reaction can be endowed with moderate hydrophobic micro-environment by nanoparticle scaffolds, eliciting enhanced ESIPT emission. The newly developed e-PNPs exhibit strong tautomeric fluorescence(e-FL), good photostability, low-toxicity and favourable biocompatibility in aqueous solution. Upon the addition of NO2-, the e-FL can be significantly quenched owing to the reaction of NO2- with the amide groups on e-PNPs. From this basis, the fluorescence detection of NO2- was implemented, which showed a linear relationship between 0 nM and 110 nM with a detection limit of 2.3 nM. Furthermore, e-PNPs were used as nanoprobes to monitor the NO2- levels in HeLa cells by fluorescence imaging, demonstrating the ability of discrimination from different concentrations of NO2-. The proposed method can be applied to a wide range of other ESIPT modules to integrate into polymer nanoparticles and offer highly sensitive nanosensing platform for bioanalysis and molecular imaging.

Impact of Lubricant Oil Additives on the Performance of Pd-Based Three-Way Catalysts

As alternative lubricant anti-wear additives are sought to reduce friction and improve overall fuel economy, it is important that these additives are also compatible with current emissions control catalysts. In the present work, a second-generation oil-miscible phosphorous-containing ionic liquid (IL), is evaluated for its impact on Pd-based three-way catalyst (TWC) reactivity and benchmarked against the industry standard zinc dialkyl-dithio-phosphate (ZDDP). The TWCs are exposed to the lubricant additives in an engine bench under four different scenarios: base case with no additive (NA), ZDDP-only, IL-only, and IL + ZDDP. The engine-aged TWC samples, along with the as-received TWC, are characterized through various analytical techniques including catalyst reactivity evaluation in a bench-flow reactor. The temperature of 50% conversion (T50) for the ZDDP-aged TWC increases by 11, 21, and 36 °C for CO, C3H6, and C3H8, respectively, as compared with the no-additive case. Similarly, the T50 for IL-only and IL + ZDDP-aged TWCs also increase as compared with the no-additive case. Even though the water-gas-shift (WGS) reactivity is similar for all engine-aged samples, the IL-aged TWC had higher oxygen storage capacity than the ZDDP-aged TWC. EPMA analysis reveals penetration of phosphorus deep into the washcoat for all engine-aged TWCs. Results from XRD indicate the presence of CePO4 and AlPO4 on the washcoat of IL, ZDDP, and IL + ZDDP-aged TWC samples but not on the fresh and NA TWC samples. Additionally, ICP-OES results show a large amount of phosphorus in the washcoat of IL, ZDDP and IL + ZDDP-aged TWC samples and a lesser amount in NA TWC samples.

The coupling interaction of NO2- with NH4+ or NO3- as an important source of N2O emission from agricultural soil in the North China Plain.

NO2- plays a crucial role in regulating N2O formation from the soil, while how it affects the production of soil N2O is still not well understood. In this study, N2O and NO emissions from an agricultural field of the North China Plain (NCP) were comparatively investigated under five different fertilizer treatments (NH4+, NO3-, NO2-, NH4+ + NO2- and NO3- + NO2-). Additionally, soil NH4+, NO2- and NO3- concentrations and the abundance of functional genes associated with nitrogen cycling were also analyzed in the incubation experiment. The results showed that the N2O average fluxes from the complex treatments of NO2- + NO3- were 1.4-2.4 times the sum of those from the separate treatments of NO2- and NO3- whereas from the complex treatments of NO2- + NH4+ were a factor of 1-1.4 larger than those from the separate treatments of NO2- and NH4+, indicating the coupling interaction of NO2- with NH4+ or NO3- makes a remarkable contribution to N2O emission from the soil. Significant reduction of the activity of N2O reductase was found in the soil with the addition of NO2-, which favored the accumulation of N2O formed through nitrification of NH4+ and denitrification of NO2-, resulting in relatively high N2O emissions from the complex treatments. As the intermediate product of nitrification and denitrification, NO2- produced is also expected to interact with NH4+ or NO3- to promote N2O emission from the soil, especially during fertilization events when NO2- is easily accumulated due to the acceleration of the nitrification and denitrification processes.

Theoretical study on the mechanisms, kinetics and ecotoxicity assessment of OH-initiated reactions of guaiacol in atmosphere and wastewater

The OH-initiated transformation mechanisms, kinetics and ecotoxicity assessment of guaiacol (2-methoxyphenol) in the presence of O2/NOx were investigated both in atmosphere and wastewater. The solvent effect lowers the energy barriers of initial OH-addition reactions more than H-abstraction reactions, leading to much higher addition branching ratio (Γadd) of 0.92 in aqueous solution than that of 0.42 in gas-phase. At 298 K, the overall rate constants of the title reactions in atmosphere and wastewater are 5.56 × 10−12 and 1.41 × 10−11 cm3 molecule−1 s−1 with corresponding half-lives of 34.6 h and 0.82 s, respectively. In atmosphere, all the proposed favorable products including nitroguaiacols, methoxybenzoquinone, 2-hydroxyphenyl formate, 2-methoxybenzene-1, 3-diol and dialdehyde could contribute to secondary organic aerosols (SOAs). In wastewater, NO2 addition reactions lead to higher toxicity of products (nitroguaiacols and 2-methoxybenzene-1, 4-diol) than that of parental guaiacol. However, O2/NO addition pathways may generate less harmful products except for methoxybenzoquinone (P3) which is with higher toxicity than guaiacol. Therefore, more attention should be focused on the products formed from OH-initiated reactions of guaiacol both in atmosphere and wastewater.

Effects of Bath Gas and NOx Addition on n-Pentane Low-Temperature Oxidation in a Jet-Stirred Reactor

The oxidation of n-pentane (C5H12) in different bath gases (He, Ar, and CO2) and in Ar with NO2 or NO addition has been studied in a jet-stirred reactor at 107 kPa, temperatures between 500 and 110...

Synthesis of 4-Oxoisoxazoline N-Oxides via Pd-Catalyzed Cyclization of Propargylic Alcohols with tert-Butyl Nitrite.

A cyclization of propargylic alcohols with tert-butyl nitrite at room temperature in air was achieved using Pd(OAc)2 as catalyst. The first reported 4-oxoisoxazoline N-oxides could be directly accessed from a range of multisubstituted propargylic alcohols in moderate to excellent yields under mild conditions. Density functional theory calculations indicated that the reaction proceeds through a palladium-catalyzed NO2 addition that efficiently generates a ketoxime radical, which eventually produces 4-oxoisoxazoline N-oxide.

Efficient toxic nitrite monitoring and removal from aqueous media with ligand based conjugate materials

This study aims to develop a highly selective conjugate material for efficient optical detection and adsorption of nitrite (NO2−) ion from waste solutions. In the present study, 1-naphthylamine ligand based conjugate material was fabricated for efficient NO2− capturing. The material was formed color and corresponding signal intensity upon addition of NO2− ion. Several experimental parameters such as materials morphology, solution acidity, contact time, competing ion, elution, maximum adsorption capacity were determined. The data clarified that the material was able to recognize the trace level NO2− based on the limit of detection of 0.23 μg/L. The solution pH was exhibited the key role and the suitable pH 4.0 was selected based on the signal intensity and adsorption efficiency. The competing ion was not affected the NO2− ion detection and removal by the material. In addition, the signal intensity was observed only for the NO2− ions and this was clarified the high selectivity towards the NO2− ions at the optimum experimental conditions. Moreover, the adsorption data were highly fitted to the Langmuir adsorption model with the monolayer coverage as the material surface was ordered homogeneity. The maximum adsorption capacity was 135.21 mg/g, which was comparable with the other forms of recent material. The materials was exhibited the high reusability based on the desorption performances. The elution was performed using 0.20 M NaOH and then the material was ready to use after washing with water without significant loss in its performance. Therefore, the data are promising to use the material in real samples treatment. Moreover, the proposed materials will attract the scientific community as suitable nanomaterial for NO2− detection and removal from contaminated water samples.

NO2 Suppression of Autoxidation-Inhibition of Gas-Phase Highly Oxidized Dimer Product Formation.

Atmospheric autoxidation of volatile organic compounds (VOC) leads to prompt formation of highly oxidized multifunctional compounds (HOM) that have been found crucial in forming ambient secondary organic aerosol (SOA). As a radical chain reaction mediated by oxidized peroxy (RO2) and alkoxy (RO) radical intermediates, the formation pathways can be intercepted by suitable reaction partners, preventing the production of the highest oxidized reaction products, and thus the formation of the most condensable material. Commonly, NO is expected to have a detrimental effect on RO2 chemistry, and thus on autoxidation, whereas the influence of NO2 is mostly neglected. Here it is shown by dedicated flow tube experiments, how high concentration of NO2 suppresses cyclohexene ozonolysis initiated autoxidation chain reaction. Importantly, the addition of NO2 ceases covalently bound dimer production, indicating their production involving acylperoxy radical (RC(O)OO•) intermediates. In related experiments NO was also shown to strongly suppress the highly oxidized product formation, but due to possibility for chain propagating reactions (as with RO2 and HO2 too), the suppression is not as absolute as with NO2. Furthermore, it is shown how NOx reactions with oxidized peroxy radicals lead into indistinguishable product compositions, complicating mass spectral assignments in any RO2 + NOx system. The present work was conducted with atmospheric pressure chemical ionization mass spectrometry (CIMS) as the detection method for the highly oxidized end-products and peroxy radical intermediates, under ambient conditions and at short few second reaction times. Specifically, the insight was gained by addition of a large amount of NO2 (and NO) to the oxidation system, upon which acylperoxy radicals reacted in RC(O)O2 + NO2 → RC(O)O2NO2 reaction to form peroxyacylnitrates, consequently shutting down the oxidation sequence.