Presence Of NH Research Articles

Ammonia Sensor Based on Co2+/SCN− Modified Core-Shell MCM-41 for Rapid Naked-Eye Colorimetric Detection

Mesoporous silica materials have been widely used as gas adsorbents due to their excellent adsorption ability, large specific surface area, simple preparation process, and convenient functionalization. In this study, a core–shell mesoporous material MCM-41@SiO2 was synthesized and functionalized by CoCl2, and subsequently KSCN, to prepare an ammonia adsorbent. The adsorbent was proved to possess high surface area, good sphericity, uniform size, good dispersibility, and high adsorption capability following DLS, SEM, TEM, and a static adsorption study. Moreover, the successful functionalization and thermal stability were confirmed by FT-IR, XPS, and TGA. The material was then used to fabricate a glass tube sensor for the rapid naked-eye detection of ammonia gas. The sensor showed good performance in terms of sensing speed, selectivity, accuracy, and reusability. Within 5 s, NH3 could be detected by the discoloration, and a wide NH3 concentration from 20 to 1000 ppm could be detected. It also showed a good linear relationship between discoloration length and ammonia concentration. A reversible color change from blue to yellow indicated the presence of NH3, which was attributed to the formation and disassembly of ammonia-containing complex [Co(NH3)6(NCS)2]. With fast adsorption, naked-eye sensing properties, and good selectivity, the sensor holds good promise for indoor NH3 sensing and other more complicated situations.

Performances and pollutant emissions of spark ignition engine using direct injection for blends of ethanol/ammonia and pure ammonia

Combustion and emissions characteristics of a spark-ignition engine using direct injection of ethanol blended with ammonia and also pure ammonia were investigated in this study. The experiments were conducted using five different fuel compositions of ethanol/ammonia (C2H5OH/NH3): 100/0, 75/25, 50/50, 25/75, and 0/100. Two strategies of injection were conducted to reach homogenous or stratified conditions with three different intake pressures, 0.5, 1.0, and 1.5 bar corresponding to 2.8, 7.9, and 12 bar of IMEP. The performances and the pollutants emissions are compared as a function of fuel compositions at identical IMEP. High stability is observed for all blends and even for pure ammonia. However, operating conditions are more restrictive for pure ammonia: the injection must be executed during the intake phase to be in a fully premixed mode to guarantee engine stability. Delaying the injection time for pure ammonia is not possible and requires the split of injections with 50% of the ammonia amount injected during the intake. The thermal efficiency is improved by adding 25% of NH3 in ethanol but NOx emissions increase. The stratified strategy for blends improves the combustion durations and the addition of ammonia decreases the NOx emission compared to the homogeneous strategy. On the contrary, CO emissions roughly increase for blends. The presence of NH3 in the fuel composition clearly influences the change of formation of NOx and CO between both strategies.

Resolving the Formation Mechanism of HONO via Ammonia-Promoted Photosensitized Conversion of Monomeric NO2 on Urban Glass Surfaces

Understanding the formation processes of nitrous acid (HONO) is crucial due to its role as a primary source of hydroxyl radicals (OH) in the urban atmosphere and its involvement in haze events. In this study, we propose a new pathway for HONO formation via the UVA-light-promoted photosensitized conversion of nitrogen dioxide (NO2) in the presence of ammonia (NH3) and polycyclic aromatic hydrocarbons (PAHs, common compounds in urban grime). This new mechanism differs from the traditional mechanism, as it does not require the formation of the NO2 dimer. Instead, the enhanced electronic interaction between the UVA-light excited triplet state of PAHs and NO2-H2O/NO2-NH3-H2O significantly reduces the energy barrier and facilitates the exothermic formation of HONO from monomeric NO2. Furthermore, the performed experiments confirmed our theoretical findings and revealed that the synergistic effect from light-excited PAHs and NH3 boosts the HONO formation with determined HONO fluxes of 3.6 × 1010 molecules cm-2 s-1 at 60% relative humidity (RH) higher than any previously reported HONO fluxes. Intriguingly, light-induced NO2 to HONO conversion yield on authentic urban grime in presence of NH3 is unprecedented 130% at 60% RH due to the role of NH3 acting as a hydrogen carrier, facilitating the transfer of hydrogen from H2O to NO2. These results show that NH3-assisted UVA-light-induced NO2 to HONO conversion on urban surfaces can be a dominant source of HONO in the metropolitan area.

Synergistic Effects of SO2 and NH3 Coexistence on SOA Formation from Gasoline Evaporative Emissions.

Vehicular evaporative emissions make an increasing contribution to anthropogenic sources of volatile organic compounds (VOCs), thus contributing to secondary organic aerosol (SOA) formation. However, few studies have been conducted on SOA formation from vehicle evaporative VOCs under complex pollution conditions with the coexistence of NOx, SO2, and NH3. In this study, the synergistic effects of SO2 and NH3 on SOA formation from gasoline evaporative VOCs with NOx were examined using a 30 m3 smog chamber with the aid of a series of mass spectrometers. Compared with the systems involving SO2 or NH3 alone, SO2 and NH3 coexistence had a greater promotion effect on SOA formation, which was larger than the cumulative effect of the two promotions alone. Meanwhile, contrasting effects of SO2 on the oxidation state (OSc) of SOA in the presence or absence of NH3 were observed, and SO2 could further increase the OSc with the coexistence of NH3. The latter was attributed to the synergistic effects of SO2 and NH3 coexistence on SOA formation, wherein N-S-O adducts can be formed from the reaction of SO2 with N-heterocycles generated in the presence of NH3. Our study contributes to the understanding of SOA formation from vehicle evaporative VOCs under highly complex pollution conditions and its atmospheric implications.

Impact of Trace Ammonia Impurities on the Utilization of Renewable Natural Gas

Renewable natural gas (RNG), produced from biogas upgrading, is an important alternative to fossil fuels for power generation. Unfortunately, RNG contains several trace contaminants that may be harmful to the existing infrastructure for its transport and use. One such contaminant is ammonia (NH3), of particular concern for RNG produced from farming operations. The presence of NH3 in RNG, particularly if it is injected into the natural gas (NG) pipeline network, can have serious consequences. These can range from damage to components of the NG infrastructure to corrosion of analytical and end-user equipment and added pollutant formation during combustion. This research project addresses all these impacts. Its objectives were (i) to investigate the potential corrosion effects of NH3 on typical pipeline materials during their exposure to RNG derived from biogas and processed to meet pipeline NG quality specifications, (ii) to study the environmental impacts and other concerns during combustion of NH3-containing RNG for power and energy production, and (iii) to analyze the potential impact of NH3-containing RNG on the performance of analytical equipment commonly used during NG distribution and end-use. This paper describes the work performed and the key findings in each of these areas.

The direct electrocatalytic oxidation of ammonia by copper-deposited nickel foam catalysts

The electrochemical oxidation process is a green and efficient strategy for ammonia removal from wastewater. Here, we investigated the direct ammonia electrochemical oxidation (AEO) and selectivity of nitrogen products (e.g. SN2, SNO2−, SNO3−) using Cu-deposited nickel foam (Cu/NF) electrode at initial pHs of 8−11 and applied electrode potentials of 0.7−1.1 V vs. Hg/HgO for a 5-h AEO reaction. The electrochemical analysis showed that Cu/NF exhibited a higher current density of 3 mA cm−2 and a larger specific capacitance of 380 µF cm−2 than those obtained by pristine NF (1.4 mA cm−2 and 210 µF cm−2) under the presence of NH3. Cu/NF performed a high NH3 removal and conversion of NH3 to NO3−, accounted for >50% and >90%, at initial pHs > 9.5 and applied electrode potentials > 0.9 V. X-ray photoelectron spectroscopy (XPS) analysis confirmed that Cu(II) and Ni(III) were electrochemically formed in the form of CuNi oxyhydroxide during the AEO reaction. At an initial pH 11 and an electrode potential of 0.9 V, the decrease of the Cu(I) proportion in the Cu(I)/Cu(II) speciation of CuNi oxyhydroxide (from 42% at 1st h to 7.2%) decreased the SN2 from 71% to 33% after the 5-h electrolysis. Furthermore, an increase of Ni/Cu ratio in the NiCu oxyhydroxyl species also favored the production of N2. The findings of this study reveal that a precise control of initial pH and electrode potential is able to alter the NiCu oxyhydroxyl species on the Cu/NF electrode surface during the AEO reaction, changing the NH3 conversion pathways.

Selective sensing performance of UV-activated ZnO nanowires decorated with Ir and Rh nanoparticles

Single-crystal zinc oxide (ZnO) nanowires (NWs) were synthesized through self-assembly hydrothermal reaction and decorated with oxidative and reductive catalytic active sites to tailor their gas sensing selectivity. The sensing performances of the developed materials were investigated under ultraviolet-light emitting diode (UV-LED) irradiation against low concentrations of nitrogen dioxide (NO2) and ammonia (NH3) gases, as oxidizing and reducing gas representatives, respectively. The growth of NWs towards the hexagonal c-axis was demonstrated, where presence of Rh3d and Ir4f active sites on the surface of ZnO NWs was observed. The sensing performance of the surface modified ZnO NWs was enhanced significantly, compared with that of the pristine ZnO NWs. The Rh-decorated ZnO NWs sensor exhibited superior performance in the detection of NO2, while the Ir sites promoted the oxidative reaction in the presence of NH3, attributed to the Fermi level of the metal-decorated films under UV irradiation.

Enhanced sensitivity towards LPG with selectivity between LPG, NO2, and NH3 by novel CoFe2O4/SiC/BaTiO3 nanocomposites

In this paper, the enhanced sensitivity and selectivity between LPG, NO2, and NH3 by novel CoFe2O4/SiC/BaTiO3 (CFO/SiC/BTO) ternary nanocomposites synthesized by chemical coprecipitation and solid-state methods have been reported. The structural and morphological properties of nanocomposites were analysed using XRD, SEM and EDS respectively. The highest dielectric permittivity ∼665 at 8 kHz for 30 wt% BTO with lowest dielectric loss at high temperature was achieved using LCR meter. Moreover, the maximum response (%) was obtained towards LPG ∼84%, while it was found to be ∼11% for NH3 and ∼23% for NO2 at 220 ppm, whilst it was achieved more than 95% above 150 °C for all the gases. Furthermore, the selectivity ∼95% at room temperature was acquired for LPG in presence of NH3. The excellent response (%) ∼ 99.68% and 99.85% was obtained for mixture of LPG-NO2 and LPG-NH3 at 300 °C for 30 wt% BTO, which was also confirmed by obtained activation energy. Accordingly, 30 wt% BTO of CFO/SiC/BTO nanocomposites is providing excellent sensitivity and selectivity towards LPG in the mixture of NO2 and NH3.

Effect of β - hydroxy - γ -aminophosphonate (β - HPC) on the hydrolytic activity of Nocardia brasiliensis as determined by FT-IR spectrometry.

The use of immunomodulatory and metabolic modulating drugs has been considered a better strategy to improve the efficacy of conventional treatments against pathogens and metabolic diseases. L-carnitine is relevant in fatty acid metabolism and energy production by β-oxidation, but it also has a beneficial therapeutic immunomodulatory effect. The β-hydroxy-γ-aminophosphonate (β-HPC) was developed, synthesized and studied in different pathologies as a more soluble and stable analog than L-carnitine, which has been studied in bacterial physiology and metabolism; therefore, we set out to investigate the direct effect of β-HPC on the metabolism of N. brasiliensis, which causes actinomycetoma in Mexico and is underdiagnosed. To analyze the effect of β-HPC on the metabolic capacity of the bacterium for the hydrolysis of substrate casein, L-tyrosine, egg yolk, and tween 80, Fourier transform infrared spectroscopy (FT-IR) was employed. It was found that β-HPC increases the metabolic activity of N. brasiliensis associated with increased growth and increased hydrolysis of the substrates tested. By the effect of β-HPC, it was observed that, in the hydrolysis of L-tyrosine, the aromatic ring and functional groups were degraded. At 1515 cm-1, any distinctive signal or peak for this amino acid was missing, almost disappearing at 839, 720, 647, and 550 cm-1. In casein, hydrolysis is enhanced in the substrate, which is evident by the presence of NH, OH, amide, and CO. In casein, hydrolysis is enhanced in the substrate, which is evident by the presence of NH, OH, amide, COO, and P = O signals, characteristic of amino acids, in addition to the increase of the amide I and II bands. In Tween 80 the H-C = and C = C signals disappear and the ether signals are concentrated, it was distinguished by the intense band at 1100 cm-1. Egg yolk showed a large accumulation of phosphate groups at 1071 cm-1, where phosvitin is located. FT-IR has served to demonstrate that β-HPC is a hydrolysis enhancer. Furthermore, by obtaining the spectrum of N. brasiliensis, we intend to use it as a quick comparison tool with other spectra related to actinobacteria. Eventually, FT-IR may serve as a species identification option.

Stable and Ordered Body-Centered Cubic PdCu Phase for Highly Selective Hydrogenation.

Phase engineering of nanomaterials plays a crucial role for regulating the catalytic performance. Nevertheless, great challenges still remain for elucidating the structure-selectivity correlation. Herein, this study demonstrates that the body-centered cubic phase of PdCu (bcc-PdCu) can serve as a highly active and selective catalyst for 3-nitrostyrene (NS) hydrogenation under mild conditions. In particular, bcc-PdCu displays a 3-nitro-ethylbenzene (NE) selectivity of 93.8% with a turnover frequency (TOF) value of 4573 h-1 at 30°C in the presence of H2 . With the assistance of NH3 ∙BH3 , the selectivity of 3-amino-styrene (AS) reaches 94.5% with a TOF value of 13719h-1 . Detailed experimental and theoretical calculations reveal that improved NE selectivity is ascribed to the selective adsorption of the CC bond and desorption of NE on bcc-PdCu. Moreover, the presence of NH3 ∙BH3 facilitates the selective hydrogenation of NO2 due to their strong interaction and thus leads to the formation of AS. This work provides an efficient selective catalyst for NS hydrogenation under mild conditions, which may attract immediate interests in the fields of materials, chemistry, and catalysis.

Density functional theory calculation of catalytic sulfidization on the azurite (0 1 1) surface by ammonium salts and its effect on flotation

In this study, we performed microflotation experiments and density functional theory (DFT) calculations to investigate the effect of ammonium salts on azurite sulfidization. The flotation recovery of azurite with ammonium salt and Na2S treatment was higher than that with Na2S treatment alone. The DFT calculation showed that the S atom in HS− could bond to Cu atoms on the azurite (011) surface, i.e., it chemically adsorbed on the azurite (011) surface to form copper sulfide species. In the presence of NH3, the adsorption energy decreased from −149.42 kJ/mol to −187.26 kJ/mol compared with only HS− adsorption, and the bond length of CuS increased from 2.17 Å to 2.30 Å, indicating enhanced adsorption of the S species. The Cu 3d and S 2p energy-level overlap range became wider, and the formed CuS species became complex after catalytic sulfidization by ammonium salts, enhancing the stability of the CuS species. During catalytic sulfidization, NH3 species desorbed from the azurite surface and returned to the solution, so ammonium species acted as a catalyst in azurite sulfidization. This work elucidated the role of ammonium salts in the enhanced sulfidization flotation of azurite at an atomic level and further supplemented our previous experimental statement.

Protection Effect of Ammonia on CeNbTi NH3-SCR Catalyst from SO2 Poisoning

CeNbTi catalyst was poisoned in different sulfur poisoning atmospheres at 300 °C for 6 h and then was evaluated for selective catalytic reduction (SCR) of NOx with NH3. The catalyst deactivation upon SO2 exposure was effectively inhibited in the presence of NH3. Temperature-programmed decomposition (TPD) analyses were applied to identify deposit species on the poisoned catalysts by comparison with several groups of reference samples. Diffuses reflectance infrared Fourier transform spectroscopy (DRIFTS) over CeNbTi catalysts with different poisoning pretreatments and gas purging sequences were designed to investigate the roles of NH3 in the removal of surface sulfites and sulfates. More ammonium sulfates including ammonium bisulfate and ammonium cerium sulfate were generated instead of inert cerium sulfate in these conditions. The mechanisms about the formation and transformation of surface deposits upon sulfur poisoning w/wo NH3 were explored, which provided a basis for developing Ce-based mixed oxides as SCR catalysts for stationary sources.

Mechanistic insights into the promotion of low-temperature NH3-SCR catalysis by copper auto-reduction in Cu-zeolites

The performance of Cu-chabazite (Cu-CHA) zeolite, the state-of-art catalyst for the ammonia-assisted selective reduction (NH3-SCR) of toxic NOx pollutants from heavy-duty diesel vehicles, is insufficient at low reaction temperatures and needs to be improved for meeting stringent emission regulations. Here, we demonstrate that the auto-reduction of isolated Cu sites (i.e. Cu2+[OH]→Cu+) in Cu-CHA could promote the low-temperature NOx abatement efficiency in NH3-SCR. Combining in situ spectroscopy, steady-state/transient kinetic measurements and computational simulations, we unveiled that Cu auto-reduction, which was driven by non-oxidative thermal activation, weakened the Cu tethering to CHA framework and thus increased the Cu mobility, particularly, in the presence of NH3. More importantly, auto-reduction-induced charge redistribution favored NO activation to form intimately interacted Cu+···NO+ pairs, which enabled alternative and highly efficient pathways leading to drastically promoted NO abatement at temperatures below 250 °C. These mechanistic findings shed new light on tuning the speciation of Cu single-sites to promote NOx reduction catalysis over Cu-zeolites.

Vanadium (oxy)nitride as a new category of anode for direct ammonia solid oxide fuel cells cells

Ammonia (NH3) is considered a potential energy carrier to be used as a fuel in energy conversion devices, such as solid oxide fuel cells (SOFCs). Nonetheless, in the presence of NH3, traditional Ni-containing anodes may suffer from poor chemical stability, resulting in its partial conversion to nickel nitride. We, therefore, propose a new composite anode for direct ammonia solid oxide fuel cells made of a metallic conducting phase, vanadium (oxy)nitride (VON), and an oxygen-ion conducting phase, (ZrO2)0.92(Y2O3)0.08 (YSZ). X-ray diffraction (XRD) reveals that the VON material is chemically compatible with YSZ. Good thermal stability was also shown under reducing conditions by thermogravimetry (TGA). Electrochemical impedance spectroscopy (EIS) showed that peak performing composition is composed of 50:50% vol of VON:YSZ at 850 °C, yielding comparable performance to that of previous reports on traditional Ni-YSZ cermets. The electrode mechanism under NH3 fuel was found to be similar to that of traditional Ni-based cermet compositions using hydrogen fuel, due to the predicted thermal decomposition of ammonia under the studied operation temperatures, i.e., ≥650 °C, while sensitivity to flow rate considerations was also highlighted. To the best of our knowledge, this work reports a completely new category of anodes for SOFC applications.

A novel resource conversion strategy of waste plastic express packaging bags using supercritical water-ammonia process: Optimization by response surface methodology

With the rapid development of e-commerce and express delivery industries, a large number of waste plastic express packaging bags (WPEPBs) are generated and urgent to be safely disposed. In this work, a novel resource conversion strategy was developed to produce high value-added chemicals from WPEPBs by supercritical water ammonia (SWA) process without any catalyst. WPEPBs could be converted into two parts by the SWA process: oil and solid residue. More than 80 % of the oil was identified as long-chain alkanes and alkenes due to the decomposition of polyethylene (PE) contained in WPEPBs. The presence of NH3 in SWA was beneficial to improve the production of long-chain alkenes. The plasticizers in WPEPBs including bisphenol A (BPA) and phthalate ester (DEHP) could be efficiently converted into aniline (≈15%) and 2-ethylhexanol (≈4 %) due to the high reactivity of NH3 in the SWA process. Compared with the degradation of WPEPBs in supercritical water, the SWA process could reduce side effects and improve the purity of target products. High-purity CaCO3 powder could be further recovered from the solid residue. The optimal parameters of the SWA process for the conversion of WPEPBs by Response Surface Methodology (RSM) were 440.5 ℃, 90 min, and CNH3 of 4.8 wt%. The conversion ratio of WPEPBs (CWPEPBs) and CaCO3 recovery ratio (RCaCO3) were 99.10 % and 98.85 %, respectively. In contrast to traditional methods for recycling of plastic waste such as mechanical recycling and incineration, the SWA process is believed to be a clean and high-efficiency resource conversion strategy for WPEPBs.

A Diamine-Oriented Biorefinery Concept Using Ammonia and Raney Ni as a Multifaceted Catalyst.

Diamines are important industrial chemicals. In this paper we outline the feasibility of lignocellulose as a source of diol-containing molecules. We also illustrate the possibility of turning these diols into their diamines in good to excellent yields. Central to these transformations is the use of commercially available Raney Ni. For diol formation, the Raney Ni engages in hydrogenation and often also demethoxylation, that way funneling multiple components to one single molecule. For diamine formation, Raney Ni catalyzes hydrogen-borrowing mediated diamination in the presence of NH3.

Synthesis and Characterization of NiO Nanoparticles by Using Thermal Decompositions of Ni(II) – ONO and ONNO Type Schiff Base Complexes

Five different Nickel (II) complexes were prepared using a ONNO type Schiff base bis-N;N’(salicylidene)-1,3-propanediamine (LH2) and an ONO type Schiff base N(2-hydroxy)salicylaldimine (SAPH2) in the presence of NH3 or amine and NiO nanoparticles were obtained with thermal decomposition of this complexes in air. The prepared complexes and Schiff bases have been characterized by element analysis, IR spectroscopy, Thermogravimetry (TG), 1HNMR and 13CNMR spectroscopy, Mass Spectrometry (MS), Atomic absorption spectrometry (AAS), and Scanning Electron Microscopy (SEM). The surface area of the obtained nanoparticle NiO material was measured by the Brunauer-Emmett-Teller (BET) method. The thermal decomposition products NiO nanoparticles were investigated with XRD, and SEM technics. SEM investigations showed that due to the very little solubility of the prepared two complexes and consequently they were precipitated in the form of nanoparticles. In addition, it observed that this very insoluble complexes are converted to NiO nanoparticles a result of thermal decomposition.

Fabrication and photoanode performance of ZnO nanoflowers in ZnO-based dye-sensitized solar cells

ZnO photoanodes consisting of nanoflowers were successfully synthesized on FTO substrates in two steps using the seed layer-hydrothermal method. To control the morphological and photovoltaic properties of ZnO thin films, three types of photoanodes were fabricated in the presence of NH3 (C1), NH3-PEG (C2) and NH3-PVA (C3). The morphological and structural properties of the produced photoanodes were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). Using these photoanodes, six different types of dye sensitized solar cell (DSSC) were obtained with Ruthenium Dye (Z907) and two different electrolytes. Photovoltaic (PV) and electrochemical impedance spectroscopy (EIS) characterization of DSSCs were performed. The maximum energy conversion efficiencies of these photoanodes in the presence of NH3, NH3-PEG and NH3-PVA were obtained as 1.57, 0.70 and 1.61, respectively, for the same type of electrolyte (AN50) under 100 mW/cm2 illumination.

Electro-synthesized composite of polyaniline and gum Arabic for colorimetric ammonia vapor detection

Polyaniline (PAni) is a conductive polymer with colorimetric properties, which can be combined with biopolymers to form novel composite materials. These materials can be used as a colorimetric sensor/indicator in the identification of different kinds of analytes. The present study aimed to develop a film of PAni and gum Arabic (GA) by electrochemical method to evaluate its potential use in a colorimetric sensor for ammonia vapor (NH3). The composite PAni/GA was prepared by electrochemical polymerization on a gold surface using the cyclic voltammetry technique. The stability of the films was evaluated in acid (HCl 0.1 mol L-1) after 25 imaging cycles. Strongly acidified gum arabic solution (pH 0.0) and a sweep speed of 10 mV s-1 caused higher current density in the film formation. The morphology of the films was observed by SEM and the presence of cracks in its structure can favor the entry of gases. The response of the composite in the presence of NH3 was measured using a colorimeter. The PAni/GA composite is a promising and rapid tool for use in colorimetric sensors in the detection of NH3.

Formation pathway of secondary inorganic aerosol and its influencing factors in Northern China: Comparison between urban and rural sites

Secondary inorganic aerosol, including sulfate, nitrate, and ammonium (SNA), is a significant source of PM2.5 during haze episodes in Northern China. A series of high-time-resolution instruments were used in collecting PM2.5 chemical components and gaseous pollutants during a regional heavy pollution process from January 12–25, 2018, at urban and rural sites. SNA, accounting for >50% of PM2.5 at both sites, had greater importance on haze formation. Gas-phase and N2O5 hydrolysis reactions were the main formation pathways of nitrate during the daytime and nighttime, respectively. The OH radical was the primary factor for gas-phase reactions. HONO photolysis played a more critical role in OH radical formation when O3 concentration decreased during the haze episode. N2O5 hydrolysis reaction was mainly affected by O3 and aerosol water content. High relative humidity, aerosol water content, and N2O5 concentrations at the urban site enhanced the hydrolysis reactions more than those at the rural site. The aqueous-phase reactions dominated the sulfate formation with the highest rate of transition metal ion catalytic and H2O2 oxidation reactions at the urban and rural sites, respectively. Elevated relative humidity and particle acidity at the urban site resulted in a higher formation rate of aqueous-phase sulfate than at the rural site. The gas-particle partition coefficient of NH3 had a negative correlation with the particle pH, and the presence of NH3 could promote the increase of SNA concentration. Thus, more attention should be paid to the differences in SNA formation between urban and rural regions when formulating air quality policies.