Aqueous Ammonia Solution Research Articles

Low-Temperature Aqueous Ammonia-Processed Copper (I) Selenocyanate Hole-Transporting Material for Efficient Inverted Perovskite Solar Cells

Significant efforts have been reported on copper(I) thiocyanate (CuSCN) as an efficient hole-transporting layer (HTL) for perovskite solar cells. Surprisingly, its higher chalcogen analogue copper (I) selenocyanate (CuSeCN) is unexplored yet, even though CuSeCN has been shown to have different properties compared to CuSCN because of its different electronegativity, polarizability, and size (Se vs S atoms). In this work, we report the synthesis of CuSeCN as an HTL in perovskite solar cells via low-temperature solution-processable deposition from an aqueous ammonia solution. The transparency and thermal stability of CuSeCN films were examined by the deposition of thin films from an aqueous ammonia solution under ambient conditions. The structural, electrical, optical, and morphological properties of the CuSeCN films were characterized by X-ray diffraction, XPS, FTIR, cyclic voltammetry, UV–vis–NIR spectroscopy, and field emission scanning electron microscopy. A single-step fast deposition–crystallization method was used to fabricate low-temperature CuSeCN-based inverted planar perovskite solar cells, with device architecture indium tin oxide (ITO)/CuSeCN/CH3NH3PbI3/PC61BM/BCP/Ag. Furthermore, to examine the effect of the thickness of the HTL on device performance, three different concentrations of CuSeCN solution were used for thin-film deposition in perovskite solar cells. The annealing temperature of the HTL films was optimized to obtain the highest possible device performance. A maximum power conversion efficiency (PCE) of 13.59% (Voc = 0.99 V, Jsc = 18.8 mA/cm2, and FF = 0.73) was achieved with 7.5 mg mL–1 of CuSeCN solution, along with negligible J–V hysteresis and reproducibility of device performance.

Biomass derived nitrogen functionalized carbon nanodots for nanomolar determination of levofloxacin in pharmaceutical and water samples.

Binder-free and efficient electrochemical sensing of levofloxacin (LF) was successfully developed based on the nitrogen-doped carbon nanodots (NCNDs). The NCNDs were synthesized by hydrothermal carbonation (180°C for 12 h), and the heteroatom was embedded in aqueous solution of ammonia (NH3). Spectral and microscopic characteristization techniques were used to analyze the topological, crystallinity, and chemical binding behavior of synthesized biomass functional material. HR-TEM image revealed a uniform spherical dot (2.96 nm), and superior quantum yield efficiency (0.42 Φ). The NCNDs was drop coated on a glassy carbon electrode (GCE) and electrochemical sensing of LF was performedby cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric i-t curve in phosphate-buffered saline (PBS; pH = 7.0). The NCNDs modified electrode showed a sharp oxidation peak at +0.95 V (vs. Ag/AgCl) with a four-fold higher current response than the bareGC electrode. The NCNDs/GCE surface not only increases the current response, but has lower detection potential, and facilitates electron transfer reaction. Under optimized working parameters, the NCNDs/GCE showed wide linear concentrations rangefrom 200 nM to 2.8 mM and a low detection limit (LOD) of 48.26 nM (S/N = 3). The electrode modified with NCNDs has high electrochemical sensing stability (RSD = 1.284 ± 0.05% over 5 days), and superior reproducibility (RSD = 1.682 ± 0.06% (n = 3)). Finally, theNCNDs modified GC electrode was successfully applied to quantify the concentration of LF in drug and river water samples with acceptable recovery percentages of 96.60-99.20% and 97.20-99.00% (n=3), respectively.

Dynamic Modeling Assessment of CO2 Capture Process Using Aqueous Ammonia

In the pursuit of addressing climate change and achieving sustainable development, this study presents a comprehensive and intricate mathematical model that provides valuable insights into the process of carbon dioxide capture using ammonia aqueous solutions as solvents. The ability of the model to accurately describe the process under consideration is supported by the validation results. Specifically, the validation process involves the examination of four parameters over the height of the absorption column. The results demonstrate a strong correlation as the model predicted profiles are in close agreement with experimental values, with an error coefficient exceeding R = 0.91. When subjecting the system to a 25% variation in flue gas inflow, the carbon capture rate exhibits a significant fluctuation (7–10%) for both increasing and decreasing cases. In addition, the validated model is scaled-up to simulate the industrial-scale ammonia-based absorption process of carbon dioxide. The simulation incorporates a column with intercooling after each layer of packing. The results indicate that by minimizing the temperature within the column, the concentration of ammonia in the clean gases obtained at the top remains below 10 ppm, while the capture rate increases up to 94%. Furthermore, the analysis of a predetermined scenario reveals that the model can effectively replicate the behavior of the system under various conditions. This finding highlights its potential utility for future applications, including process optimization and the implementation of control techniques aimed at mitigating the above-mentioned drawbacks, such as solvent loss due to vaporization.

REACTOR SİMULATİON DURİNG ANİLİNE SYNTHESİS

Study of reactor modeling in the process of aniline synthesis. Every year the demand for aniline is growing all over the world, and, accordingly, the capacity of its production. The areas of consumption of this product are different: the production of isocyanates used in the industry of building materials (foams, decorative parts, pipe insulation, etc.), in the shoe industry, additives to motor fuels; production of pharmaceutical preparations; organic dyes and pigments; herbicides.The object of study of this work is an industrial reactor related to shell-and-tube vertical apparatuses.The purpose of this work is to improve the process of synthesis of aniline using a mathematical model.The parameters of the equations describing the rate of the aniline synthesis process are determined; a mathematical model of an industrial reactor was developed taking into account the strong exothermicity of the aniline formation reaction.A computer model of the aniline synthesis reactor was developed, the adequacy of which was confirmed experimentally, allowing to determine the values of output characteristics in a wide range of changes in technological and design parameters; the influence of technological and design parameters on the process of aniline synthesis was studied. Based on the results of scientific research, 2 abstracts of conferences were published. Beginning in the early 1970s, American Cyanamide (USA) developed an original technology to produce aniline through the ammonolysis of benzoic acid. Benzoic acid was reacted with aqueous ammonia solution in the presence of cupric oxide at 215-220 °C and 3.5-4.2 MPa. Benzoic acid is produced according to known technology through the liquid phase oxidation of toluene with the help of cobalt salts at a temperature of 130-140 ° C and 0.21-0.22 MPa under strong heat removal conditions. Keywords: aniline synthesis. aniline production parameters, mathematical model of the reactor.

Modulating the coadsoption of hydroxyl and nitrogenous groups induced by Ni and Cu doping on FeOOH for accelerating dehydrogenation in the ammonia oxidation reaction

Owing to its high hydrogen content and carbon-free nature, ammonia is a promising energy carrier used in powering fuel cells and an alternative oxidation substrate to water in electrolytic hydrogen production devices. However, the insufficient mechanistic understanding and the lack of inexpensive and efficient catalysts for the ammonia electro-oxidation reaction (AOR) have hampered the development of the ammonia-based energy system. In this work, novel Ni and Cu co-doped porous FeOOH nanorods (NiCu-FeOOH) synthesized by a light-induced chemical precipitation method can serve as the AOR catalyst with efficient catalytic activity (1.41 V at an anodic current density of 10 mA cm−2) and enhanced stability in an aqueous ammonia solution. According to the experimental data and theoretical calculation results, the synergistic effect of heterogeneous Ni and Cu atoms makes Ni and Fe sites on the surface of NiCu-FeOOH exhibit a suitable electronic structure to coadsorb nitrogenous intermediates and hydroxyl groups at the top of the volcano plot and thereby accelerate dehydrogenation in the AOR. The backward shift of the rate-determining step (RDS) (⋆NH2 + ⋆OH formation step shifts to ⋆N2H3 + ⋆OH formation step) and the lower energy barrier of the RDS (0.86 eV) reveal that the Ni and Cu co-doping makes FeOOH crystals active for the AOR. The coadsorption reaction pathway involved in nitrogenous intermediates and hydroxyl groups has been in-novatively proposed to effectively describe and simulate the AOR process, which opens a new horizon to design low-cost and stable AOR catalysts.

Ecofriendly synthesis of hydrated manganese oxide and its efficient adsorption of lead ions from water

Abstract Utilizing the waste liquid derived from graphene oxide synthesis as raw material, hydrated manganese oxide (HMO) was prepared by a chemical precipitation method with sodium hydroxide solution or aqueous ammonia solution. The HMO samples were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, Zeta potential analyzer, and scanning electron microscopy. The adsorption characteristics of the HMO samples were examined through lead ion adsorption from water. The effects of adsorption temperature, starting lead ion concentration, and adsorption time on the lead ion adsorption capacity were investigated. The relevant data agreed well with the pseudo-second-order kinetic model and the Langmuir isotherm model. Additionally, the maximum adsorption capacities of HMO-1 are 70.897 mg g−1, 76.660 mg g−1, and 79.424 mg g−1 for the lead ions at 298 K, 308 K, and 318 K, respectively. The lead ion adsorption mechanism of HMO has been explained. The findings indicate the as-synthesized HMO can be used as an efficient adsorbent material for eliminating lead ions from water.

Solvolysis of 2’-deoxyribonucleosides and oligo-2’-deoxyribonucleotides in aqueous pyrrolidine or ammonia solutions

To assess the feasibility of high-temperature aminolysis of deoxyribooligonucleotides containing rare bases as a method to determine their base sequence, the 2’-β-D-deoxyribosides of 5-bromouracil, 2-aminopurine, uracil, adenine, cytosine, 5-methylcytosine, hypoxanthine, N6-methyladenine, N4-ethylcytosine, and guanine were compared as to their rate of degradation in 0.5 M aqueous pyrrolidine at 110 °C, conditions used earlier in the analysis of oligonucleotides containing only the canonical bases. The reaction mixtures were analyzed by chromatography on Zorbax XDB-CN and UV absorption spectroscopy. The first-order rate constants for the nucleoside degradations decreased in the above order, spanning a wide range of reactivities. Some of these nucleosides were also tested in 0.5 M aqueous ammonia at 110 °C, giving similar first-order rate constants, except for 2’-deoxyguanosine, which is much more reactive with ammonia, due to the lower basicity of this reagent, leaving a larger proportion of the nucleoside in the non-ionized form, susceptible to nucleophilic attack at the base. Short oligothymidylates containing a single 2-aminopurine, adenine, guanine, or cytosine unit in central position were tested in pyrrolidinolysis, to determine the cleavage rates at these sites and the dependence of these cleavage rates on oligonucleotide length. A model decadeoxyribonucleotide containing all four canonical bases was also pyrrolidinolyzed, followed by ion-exchange chromatography, to deduce the nucleotide sequence from the resulting chromatographic profile.

Effect of the Synthesis Time on Structural Properties of Copper Oxide

The structural properties of the CuO nanopowder oxide prepared reflux techniquewithout any templates or surfactant, using copper nitrate hydrate (Cu(NO)3 3H2O) in deionizedwater with aqueous ammonia solution are reported. The Xrd analysis data and processing in originpro program used to get FWHM and integral width to study the effect of different synthesis timeswas studied on the structural properties. It was found that values of crystal sizes are 17.274nm,17.746nm, and 18.560nm, the size of nanoparticles is determined by Halder-Wagner, and 15.796nm, 15.851nm, and 16.52nm, were calculated by Size-Strain Plot (SSP) method. The Sample wasconsidered to determine physical and microstructural parameters such as internal strain,dislocations density, surface area, and the number of unit cells and then to compare the results.

Кинетика растворения триоксида молибдена в щелочной среде

The paper presents experimental study results of the MoO3 powder samples dissolution kinetics in the aqueous ammonia solution at various pH concentrations and values. Molybdenum ions concentration in the filtrate samples was determined spectrophotometrically. Kinetic characteristics were obtained, and kinetic parameters (specific dissolution rate, reaction order with respect to the H+ ion) were calculated. It was established that the dissolution rate was increasing in the ammonia solution concentration range of 0.02--1.26 mol/l, and with the growing pH it passed through the maximum. Taking into account the acid-base equilibria constants, the dissolution process was simulated, and its stage-by-stage nature was established. Fractional reaction order with respect to the H+ ions calculated from the curves plotted in the α--t/t0.5 coordinates (affine transformation method) indicated the adsorption mechanism of dissolution. It was shown that the MoO3 dissolution proceeded with formation of the intermediate adsorption complexes. Due to the HMoO4- low concentration in the MoO3 concentration within the studied pH range by the surface-active particle, on which groups of ions were adsorbed, the MoO4- could be considered. The results obtained are an addition to the data possessed on the molybdenum oxide phase and other transitional metals behavior. They could be applied in the practical applications associated with dissolving molybdenum in the alkaline electrolytes

高濃度短期暴露リスク評価のための非定常室内濃度分布予測手法の開発（第2報）：屋内での液体化学物質漏洩を想定した経気道暴露濃度予測

Recently, health risk assessment of chemical substances has become a legal requirement, and accordingly, estimation of indoor gas concentrations and their impact on workers has taken on increasing importance. Therefore, we have developed a numerical model based on CFD (Computational Fluid Dynamics) methods to predict transient and non-uniform concentration distributions for chemical substances in enclosed spaces. This paper (Part 2) reports on the heterogeneous concentration distributions of ethanol and aqueous ammonia solutions formed in a full-scale environment, the microclimate around the human body, and the risk assessment of trans-airway exposure.

Construction of the multi-layer TiO2-NTs/Sb-SnO2/PbO2 electrode for the highly efficient and selective oxidation of ammonia in aqueous solution: Characterization, performance and mechanism

Electrochemical oxidation is a promising technology to convert ammonia nitrogen to environmental-friendly gaseous nitrogen, but the high cost of the precious metal as an electrode limits its application. Herein, the multi-layer TiO2-NTs/Sb-SnO2/PbO2 electrode, a cheap and efficient dimensionally stable anode (DSA), was constructed for selective electrocatalytic oxidation of ammonia. The surface morphology, crystalline structure, and composition of the TiO2-NTs/Sb-SnO2/PbO2 electrode were investigated by the field emission scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The synergistic effect of the multi-layer structures of the electrode contributed to a stable structure and efficient electrocatalytic activity. Accelerated lifetime measurements and electrode recycling tests proved that the electrode possessed outstanding stability and long life with continuously used for 935 h. Compared with the commercial Ti/RuO2-IrO2, the TiO2-NTs/Sb-SnO2/PbO2 electrode displayed a more excellent performance of chlorine evolution and higher removal efficiency of ammonia. Under the optimal conditions, 30 mg/L of ammonia nitrogen could be completely removed with 92.3% selective conversion to gaseous nitrogen after 60 min. Moreover, the difference between oxygen evolution potential and chlorine evolution potential exceeded 0.45 V on the TiO2-NTs/Sb-SnO2/PbO2 electrode, which enhanced the anodic chlorine evolution reaction. Hypochlorite radical (ClO•) was supposed as the dominant oxidant to transform ammonia in water, which could promote ammonia removal and the selectivity of gaseous nitrogen with minimizing by-products formation such as nitrite and nitrate, etc. Therefore, this study suggests that the constructed multi-layer TiO2-NTs/Sb-SnO2/PbO2 electrode might be a promising anode for the electrochemical oxidation of ammonia nitrogen to N2 in an aqueous solution.

New Zwitterionic Oligonucleotides: Preparation and Complementary Binding

New zwitter-ionic oligonucleotide derivatives containing 1,2,3,4-tetrahydroisoquinoline-7-sulfonyl phosphoramidate group are described. Automated synthesis of these compounds was carried out according to the β-cyanoethyl phosphoramidite scheme using the Staudinger reaction between 2-trifluoroacetyl-1,2,3,4-tetrahydroisoquinoline-7-sulfonyl azide and phosphite triester within an oligonucleotide grafted to a polymer support. 1,2,3,4-Tetrahydroisoquinoline-7-sulfonyl phosphoramidate group (THIQ) proved to be stable under the conditions of standard oligonucleotide synthesis, including the removal of protective groups and cleavage of the oligonucleotide from the polymer support by treatment with a mixture of concentrated aqueous solutions of ammonia and methylamine (1 : 1) at 55oC. Oligonucleotides modified by one to five THIQ groups in various positions were obtained. The zwitter-ionic character of the obtained derivatives was reflected in their different mobility under conditions of denaturing PAGE. The thermal stability of the duplexes of oligodeoxynucleotides containing THIQ groups with complementary DNA and RNA differed only slightly from that of natural DNA:DNA and DNA:RNA duplexes. The results obtained suggest the possible use of oligonucleotides modified with zwitterionic THIQ groups as antisense therapeutic agents.

Efficient removal of ammonium in aqueous solution by ultrasonic magnesium-modified biochar

Ammonium is one of the most important nutrients in agricultural wastewater, and its excessive existence will pose a threat to ecosystem and even human life. The cavitation effect generated by ultrasonic waves with huge energy can break the carbon bonds of biochar and thus increase the abundance of functional groups. In order to adsorb ammonium effectively in water, we used ultrasound to improve biochar or magnesium-loaded biochar performance in removing wastewater pollutant. Batch experiments with material characterization and adsorption models were conducted to assess adsorption characteristics. The nano-biochar (NBC) was obtained after the ultrasonic modification, with porosity, cation exchange capacity (CEC), zero point of charge (pHpzc), and functional groups (–OH, C–O, C–O–H, C–H) effectively being improved, indicating OH– and H+ were separated from water and bound to biochar to form functional groups during ultrasonic cavitation. The nano-Mg-biochar (NMBC) also increased the functional group of metal oxides. The ammonium adsorption of NBC and NMBC was dominated by intraparticle diffusion. The observed ammonium adsorption capacity of NBC and NMBC was best described by the Langmuir isotherm, implying the adsorption derived from the energetically homogeneous surface. Moreover, the maximum adsorption capacities for NH4+ on NBC, and NMBC were 13.589, and 23.777 mg·g−1, respectively. Ultrasound improved the maximum ammonium adsorption capacity of raw biochar and Mg-biochar through electron attraction and ion exchange, respectively. Notably, ultrasonic modification causes a more uniform distribution of chemical crystals in the biochar and broken carbon bond to combine with more functional groups, which would be a significant way to reorganize functional groups directionally and optimize the adsorption performance of materials.

New Zwitter-Ionic Oligonucleotides: Preparation and Complementary Binding

New zwitter-ionic oligonucleotide derivatives containing 1,2,3,4-tetrahydroisoquinoline-7-sulfonyl phosphoramidate group are described. Automated synthesis of these compounds was carried out according to the β-cyanoethyl phosphoramidite scheme via the Staudinger reaction between 2-trifluoroacetyl-1,2,3,4-tetrahydroisoquinoline-7-sulfonyl azide and phosphite triester within oligonucleotide grafted to polymer support. 1,2,3,4-Tetrahydroisoquinoline-7-sulfonyl phosphoramidate group (THIQ) was stable under the conditions of standard oligonucleotide synthesis, including the removal of protective groups and cleavage of the oligonucleotide from the polymer support by treatment with a mixture of concentrated aqueous solutions of ammonia and methylamine (1 : 1) at 55°C. Oligonucleotides modified by one to five THIQ groups in various positions were obtained. The zwitter-ionic character of the obtained derivatives was reflected in their varying mobility under conditions of denaturing PAGE. The thermal stability of the duplexes of oligodeoxynucleotides containing THIQ groups with complementary DNA and RNA only slightly differed from that of natural DNA:DNA and DNA:RNA duplexes. The results reported suggest that oligonucleotides modified with zwitter-ionic THIQ groups as antisense therapeutic agents.

Degree of Dissolution of Nickel(II) Hydroxide in Mixtures of Aqueous Solutions of Ammonia and Ammonium Bicarbonate

The degree of dissolution of nickel(II) hydroxide in mixtures of aqueous solutions of ammonia and ammonium bicarbonate has been studied. The equilibrium between the solid and liquid phases was reached in 11–12 h after the start of experiment. Nickel(II) hydroxide showed higher solubility in the ammonia–carbonate mixture compared with aqueous solutions of ammonia and ammonium bicarbonate. The ratio of ammonium bicarbonate and ammonia concentrations in solution at which the highest degree of dissolution of Ni(OH)2 was achieved was determined. An analytical description of the ion-molecular equilibrium in the ammonia– carbonate mixture was given, and the equilibrium concentrations of molecules and ions in the system were calculated. A stoichiometric equation describing the dissolution of nickel(II) hydroxide in an ammonia–carbonate solution was given.

Selective non-catalytic denitrification of biomass combustion flue gases (synthetic mixture)

Despite many benefits of agricultural biomass utilization as an energy source, there are certain disadvantages such as the possible high emission of NOx. The NOx emission represents one of the key challenges for agricultural biomass use as a fuel. The experimental denitrification chamber was used to evaluate the impact of initial NO content, NH3:NO molar ratio, flue gas temperature, and the temperature difference between two denitrification chamber sections on NOx reduction using ammonia aqueous solution. The optimization of experimental conditions was done in the NO concentration range from 200-800 ppm, NH3:NO molar ratios from 0.31-3 and second chamber section temperature range from 770-67?C. The denitrification process under controlled conditions is the starting point for the optimization of the secondary denitrification technique of selective non-catalytic reduction SNCR process on real-scale plants combusting biomass or any other fuels with increased NOx emission.

Degree of Dissolution of Nickel(II) Hydroxide in Mixtures of Aqueous Solutions of Ammonia and Ammonium Bicarbonate

Degree of Dissolution of Nickel(II) Hydroxide in Mixtures of Aqueous Solutions of Ammonia and Ammonium Bicarbonate

Effects of Hydrothermal Treatment on Mesopore Structure and Connectivity in Doped Ceria-Zirconia Mixed Oxides.

Pore size and pore connectivity control diffusion-based transport in mesopores, a crucial property governing the performance of heterogeneous catalysts. In many cases, transition-metal oxide catalyst materials are prepared from molecular precursors involving hydrothermal treatment followed by heat treatment. Here, we investigate the effects of such a hydrothermal aftertreatment step, using an aqueous ammonia solution, on the disordered mesopore network of CexZr1-x-y-zYyLazO2-δ mixed oxides. This procedure is a common synthesis step in the preparation of such ceria-based oxygen storage materials applied in three-way catalysis, employed to improve the materials' thermal stability. We perform state-of-the-art Ar-physisorption analysis, especially advanced hysteresis scanning, to paint a detailed picture of the alterations in mesopore space caused by the hydrothermal aftertreatment and subsequent aging at 1050 °C. Furthermore, we investigate the network characteristics by electron tomography in combination with suitable statistical analysis, enabling a consistent interpretation of the desorption scans (physisorption). The results indicate that the hydrothermal aftertreatment enhances the mesopore connectivity of the continuous 3D network by widening pores and especially necks, hence facilitating accessibility to the particles' internal surface area and the ability to better withstand high temperatures.

The Influence of Some Factors on the Water Electrical Conductivity Variation Rate in the Low-Frequency Contact Sensors of Conductometers

The aim of the work is to study ways to improve the accuracy of water and steam condensate electrical conductivity measurements by evaluating the effect the parameters of the medium analyzed have on the time constant of the conductometer low-frequency contact sensors. Conductometers are currently among the most widely used and reliable instruments applied in cycle chemistry monitoring systems. The electrical conductivity of process media at thermal and nuclear power plants is measured predominantly with the use of contact low-frequency sensors of conductometers. In this regard, a study of the influence of individual factors on the accuracy of electrical conductivity measurements is a topical and demanded issue. The article presents the results obtained from a study of the effect the sample temperature, flow rate and ionic composition have on the electrical conductivity variation rate in dosing ammonia used for main condensate and feed water correction treatment. A comparative analysis of the obtained dependences of the electrical conductivity time constant on the studied perturbations as applied to low-frequency conductometers of various manufacturers is performed. The experiment conducting procedure and the technical characteristics of the instruments used for electrical conductivity measurements are given. As a result of the accomplished study, the factors affecting the time constant of low-frequency flow conductometers of various manufacturers have been substantiated by experiment, and the accuracy of the obtained measured electrical conductivity values for various sample parameters has been given. The study of the effect the sample qualitative composition has on the conductometer sensor time constant has shown a high variation rate of electrical conductivity values at an ammonia concentration in the medium analyzed up to 300 µg/dm3 followed by a gradual decrease in the conductivity variation rate in the interval up to 1000 µg/dm3. It is shown that the combined dosing of ammonium ions and bicarbonates leads to an increase in the time constant value in comparison with the case of dosing only an aqueous solution of ammonia. Optimal sample parameters (temperature and flow rate) are recommended to obtain more reliable measurements of the process water electrical conductivity at thermal and nuclear power plants.

Ignition improvers for aqueous ammonia as marine fuel

The potential of three molecules NH4NO2, H2O2 and O3 to ignite aqueous solutions of ammonia (25% by mass) as fuel, was investigated using chemical kinetic simulations at conditions representative of a two-stroke marine diesel engine. The purpose was to address two of the most prominent issues with making ammonia a practical fuel for marine applications: the difficulty of igniting ammonia, and the safety concerns regarding its volatility and toxicity. The ignition simulations carried out to this end used a two-zone reactor model of the engine, representing the ignition zone into which fuel was injected, and the bulk cylinder gases, respectively. The results suggested that all three ignition improving molecules were able to ignite aqueous ammonia reliably and at high combustion efficiency with acceptable levels of NO, N2O and NH3 emissions. Among the three fuel formulations investigated, H2O2 as 12% aqueous solution by mass, promised the lowest emissions of NO and N2O in the exhaust gases. This ignition improver in aqueous solution added in a mole fraction of 0.15 to a mole fraction of 0.85 aqueous ammonia having an ammonia fraction of 25% by mass promised to be the most practical solution, since it is stable and can be stored safely in a separate tank until injected into the engine.