Solubility of Lead Nitrate in Aqueous Solutions of Nitric Acid and Iron(III) Nitrate

Solubility of lead(II) nitrate in the system H₂O-Fe(NO₃)₃-HNO₃ was studied using the simplex-lattice method of experiment design.     

Calculated and Experimentally Obtained Heats of Combustion of Hydrazinium Nitrate,Monomethylhydrazinium Nitrate,and N,N‐Dimethylhydrazinium Nitrate

The heats of combustion were determined experimentally and calculated thermodynamically for the following compounds: hydrazinium nitrate, [H₂NNH₃][NO₃] ( 1 ); monomethylhydrazinium nitrate, [H₂NNH₂(CH₃)][NO₃] ( 2 ); and N, N‐dimethylhydrazinium nitrate, [H₂NNH(CH₃)₂][NO₃] ( 3 ).The agreement between the experimental and theoretical values (in parentheses) is very satisfactory: 1 , 1035 (1157); 2 , 2490 (2389); 3 , 3542 (3376) kcal kg^—1.     

Synthesis and Structure of Tetraphenylantimony Nitrate

The reaction of pentaphenylantimony with triphenylantimony dinitrate in toluene gives tetraphenylantimony nitrate in 99% yield. The X-ray diffraction data show that the antimony atom in the molecule of tetraphenylantimony nitrate has a distorted trigonal-bipyramidal coordination with axial location of the oxygen atom of the nitrate group. The Sb-O, Sb_{a x}, and Sb-C_{e q} bond lengths in two independent molecules of tetraphenylantimony nitrate are 2.498(3), 2.548(2); 2.134(3), 2.138(3); and 2.101(3)-2.112 Å.     

Sonochemical Synthesis of Layered Copper Hydroxy Nitrate Nanosheets

Sonochemical reduction of copper nitrate, using 20 kHz ultrasound in aqueous solutions in the presence of urea, led to the formation of layered copper hydroxy nitrate nanosheets, as evidenced by scanning and transmission electron microscopy images. Fourier‐transform infrared, X‐ray diffraction, and X‐ray photoelectron spectroscopy analyses were used to characterize layered Cu₂(OH)₃NO₃ nanosheets. The ultrasound‐assisted progressive hydrolysis of urea and in situ formation of Cu(0) through the sonochemical reduction process induced homogeneous nucleation and crystallization of layered Cu₂(OH)₃NO₃ nanosheets.     

Two New Lead(II) Coordination Polymers with (Substituted) Bipyridine and Auxiliary Nitrate Ligands

The reaction of lead(II) nitrate with 4,4′‐bipyridine (4,4′‐bpy) and 4,4′‐dimethyl‐2,2′‐bipyridine (4,4′‐dm‐2,2′‐bpy) or 5,5′‐dimethyl‐2,2′‐bipyridine (5,5′‐dm‐2,2′‐bpy) resulted in the fomation of single crystals of [Pb₂(4,4′‐bpy)(5,5′‐dm‐2,2′‐bpy)₂(NO₃)₄] ( 1 ) and [Pb₃(4,4′‐bpy)₂(4,4′‐dm‐2,2′‐bpy)₂(NO₃)₆] ( 2 ). The new compounds have been characterized by single‐crystal X‐ray diffraction structure analysis as well as through elemental analysis, IR, ¹H‐NMR and ¹³C‐NMR spectroscopy and their stability has been studied by thermal analysis. In the crystal structure of ( 1 ) formula‐like dimers are further connected to a 2‐D network through the auxiliary nitrate ligands. The crystal structure of ( 2 ) exhibits two crystallographically independent Pb^II central atoms (in a ratio of 1:2). With the aid of the 4,4′‐bpy and the nitrate ions, a 3‐D polymeric structure is achieved.     

Activity Coefficients of Uranyl Nitrate and Nitric Acid in Aqueous Mixtures

The activity coefficients of nitric acid and uranyl nitrate in in aqueous mixtures are necessary to model the system H₂O-HNO₃-UO₂(NO₃)₂-TBP-diluent. Three methods have been compared in this work to determine activity coefficients based on experimental data, Pitzer's equation or Zdanovskiy's rule. Acid activities have been calculated from the data of two first methods. These results were compared with the data of third method. Errors were about 3.3.%. Activity coefficients of uranyl nitrate γ_U as a function of concentration of uranyl nitrate and nitric acid were determined in 76 mixed solutions. The equation to calculate γ_U was proposed.     

Differential Pulse Polarographic Determination of Nitrate in AUT Solution

A differential pulse polarographic method for the determination of nitrate ion has been developed. With 0.5 M CaCl₂ as supporting electrolyte, NO^?₃ is reduced to give a peak with E_1/2=–1.836 Volt vs. the Ag/AgCl electrode. The differential pulse polarographic peak height is proportional to the nitrate concentration from 20 to 60 ppm. The detection limit for nitrate is 2 ppm in pure aqueous solution. In the determination of 40 ppm nitrate a relative precision (relative standard deviation) of less than 2% was achieved. Nitrite interferes seriously and should be absent if accurate results are required. The method has been applied to the determination of nitrate in Ammonium Uranyl Tricarbonate (AUT) Solution, results obtained by this method are compared to those obtained by ion chromatography. The agreement between the two sets of results suggests that the DPP method can be used with a fair degree of confidence.     

Nitrate ion transport across TBP-kerosene oil supported liquid membranes coupled with uranyl ions

The role of nitrate ions in uranyl ions transport across TBP-kerosene oil supported liquid membranes (SLM) at varied concentrations of HNO₃ and NaNO₃ has been studied. It has been found that nitrate ions move faster compared to uranyl ions at the uranium feed solution concentrations studied. The nitrate to uranyl ions flux ratio vary from 355 to 2636 under different chemical conditions. At low uranium concentration the nitrate ions transport as HNO₃ · TBP, in addition to as UO₂(NO₃)₂ · 2TBP type complex species. The flux of nitrate ions is of the order of 12.10 · 10^–3 mol · m^–2 · s^–1 compared to that of uranium ions (4.56 · 10^–6 mol · m^–2 · s^–1). The permeability coefficient of the membrane for nitrate ions varies with chemical composition of the feed solution and is in the order of 2.5 · 10^–10 m^–2 · s^–1. The data is useful to estimate the nitrate ions required to move a given amount of uranyl ions across such an SLM and in simple solvent extraction.     

Mechanism of Electrodeposition of Lead Dioxide from Nitrate Solutions

The lead dioxide electrodeposition (LDE) from nitrate electrolytes is studied by the rotating disk electrode, cyclic voltammetry, and electrode impedance methods. A four-stage kinetic scheme of the LDE reaction is proposed: (1) the electron transfer and generation of oxygen-containing species on the electrode surface; (2) the species interact with lead ions, forming an oxygen-containing intermediate product of Pb(III) of the type Pb(OH)²⁺, which is not fixed on the electrode surface; (3) the product is oxidized, with the transfer of the second electron, forming compounds of Pb(IV) associated with oxygen (of the type Pb(OH)²⁺ ₂); and (4) the latter decomposes via a chemical mechanism to form PbO₂. The rate-determining stage of the LDE process is essentially dependent on the potential and state of the electrode surface, concentration of Pb(II) ions in solution, and hydrodynamic conditions of experiment. The proposed scheme explains within a unified mechanism of the LDE reaction all the experimental data obtained both in this work and in the literature.     

Sequential Spectrophotometric Determination of Microgram Amounts of Nitrate and Nitrite in Mixtures

This paper describes three new methods: the first may be used for the determination of nitrite; the second is applicable to determination of nitrate; and the third permits sequential determination of both nitrite and nitrate in mixtures with no prior separation. For the determination of nitrite and nitrate in synthetic mixtures containing 1:5 to 5:1 ratios of the ions, in tap water, and in river water, mean recoveries (for 3 to 22 μg of added NO⁻₃and NO⁻₂) are 96.1 and 98.1% (n= 15) and coefficients of variation are 2.2 and 2.5% for NO⁻₃and NO⁻₂(n= 5), respectively.     

Alert Electrodes for Continuous Monitoring of Nitrate Ions in Natural Water

In this study, simple disk electrodes were tested to monitor nitrate ion level in raw water: a Cu rod (3.1 mm diameter), a Pd rod (4 mm diameter) and an electrochemical copper deposit on Pd disk. These electrodes were able to detect significant variations of nitrate ions rate in synthetic media and in natural water. The influence of some ions such as SO₄^2?, Mg²⁺, HCO₃^?, Cl^?, NH₄⁺ and Ca²⁺ were also tested. These electrodes, working at potentials close to ?1.5 V, were able to detect a 2 ppm nitrate ion variation in natural water. The preliminary results showed these electrodes should be promising alert systems for the in‐situ monitoring of nitrate ion level in natural waters.     

Nitrate Removal and Nitrate Removal Velocity in Coastal Louisiana Freshwater Wetlands

Nitrate removal and nitrate removal velocity rate were determined for Mississippi River deltaic plain forested-tupelo dominated wetland, and a floating emergent freshwater marsh. Nitrate removal rate from floodwater was 19.45 and 48.90 mg N m^?2 d^?1 for two forested-tupelo wetland sites and 48.41 and 46.98 mg N m^?2 d^?1 at two floating emergent freshwater marsh sites. The removal velocity constants (k) of NO₃-N ranged from 0.44 to 1.44 per day for the four site studies. Removal velocity of nitrate from the water column was faster in the floating emergent marsh cores than from the forested wetland course, which contained more sediment. Results demonstrated that removal velocity is an important parameter when estimating nitrate removal from floodwater. Results also demonstrated the two freshwater wetland habitats had a high capacity for processing any nitrate entering the wetlands from adjacent agriculture area. Removal was attributed to denitrification and diffusion.     

Investigation of the Effect of Various Substituents on the Density of Tetrazolium Nitrate Salts as Green Energetic Materials

The substitution effect of various functional groups such as –NO₂, –CN, –N₃, –NF₂, and –NH₂ on the density of tetrazolium nitrate salts is investigated through multiple linear regression method. The methodology of this work introduces a new model, which related density of tetrazolium nitrate salts to the number of fluorine and nitrogen atoms, the presence of NF₂ groups, NO₂ groups, as well as CH₃ groups in the structural formula. The new reliable correlation shows that the NF₂ and NO₂ group can cause increasing the density of tetrazolium nitrate salts, especially NO₂, whereas the CH₃ group can decrease their density. The new proposed relationship has good reliability and predictability, so it can be used to design new rich nitrogen compounds based on tetrazolium nitrate salts as green energetic materials. These results are also tested for N,N′‐azo‐1,2,4‐triazolium nitrate salts, which is caused to derive another correlation. This correlation shows that the presence of NF₂ functional groups increases the density of N,N′‐azo‐1,2,4‐triazolium nitrate salts as well as the value of n_O/n_C.     

Effect of Ammonium Ions on the Radiation Degradation of Potassium Nitrate

The formation and thermal conversion of paramagnetic centers in -irradiated single crystals of potassium nitrate with an ammonium nitrate impurity was studied by EPR spectroscopy. It was found that the presence of ammonium nitrate decreased the radiation-chemical yield of nitrite ions, which are one of the final radiolysis products of nitrate-containing compounds. An analysis of the results of a study on NO₂ orientation in the KNO₃ crystal lattice with an impurity of NH⁺ ₄ allowed us to propose a mechanism for selective N–O bond rupture in the radiation-stimulated dissociation of the nitrate ion in a potassium nitrate matrix.     

Fabrication of a Nitrate Selective Electrode for Determination of Nitrate in Fertilizers by Using Flow Injection Analysis System

A nitrate ion selective electrode (nitrate-ISE) based on pyrrole modification on a common pencil lead was proposed. The lab-made nitrate-ISE was easily constructed by pyrrole polymerization with nitrate ion as the dopant using cyclic voltammetry. The fabricated nitrate-ISE was then coupled with flow injection analysis (FIA) for an automatic system. The flow potentiometry provided working range of 1x10^-4 to 4x10^-3 mol L^-1 of nitrate and allowed sample throughput up to 50 samples h^-1. Linear regression analysis showed good agreement (r²=0.9961) with Nernstian response. This system was applied to determine nitrate-nitrogen (nitrate-N) in fertilizer samples.     

Integrated Tandem Electrochemical-chemical-electrochemical Coupling of Biomass and Nitrate to Sustainable Alanine

Alanine is widely employed for synthesizing polymers, pharmaceuticals, and agrochemicals. Electrocatalytic coupling of biomass molecules and waste nitrate is attractive for the nitrate removal and alanine production under ambient conditions. However, the reaction efficiency is relatively low due to the activation of the stable substrates, and the coupling of two reactive intermediates remains challenging. Herein, we realize the integrated tandem electrochemical-chemical-electochemical synthesis of alanine from the biomass-derived pyruvic acid (PA) and waste nitrate (NO₃⁻) catalyzed by PdCu nano-bead-wires (PdCu NBWs). The overall reaction pathway is demonstrated as a multiple-step catalytic cascade process via coupling the reactive intermediates NH₂OH and PA on the catalyst surface. Interestingly, in this integrated tandem electrochemical-chemical-electrochemical catalytic cascade process, Cu facilitates the electrochemical reduction of nitrate to NH₂OH intermediates, which chemically couple with PA to form the pyruvic oxime, and Pd promotes the electrochemical reduction of pyruvic oxime to the desirable alanine. This work provides a green strategy to convert waste NO₃⁻ to wealth and enriches the substrate scope of renewable biomass feedstocks to produce high-value amino acids.     

A Complex between C-Methylcalix[4]resorcinarene and Triethylammonium Nitrate

Abstract

The synthesis and crystal structure of the complex formed by the all-cis epimer of C-methylcalix[4]resorcinarene (1) and triethylammonium nitrate are reported. “1.(HNEt⁺ ₃)₄. (NO^? ₃)₄(2)”, crystallizes in the monoclinic space group P2₁/n, a=25.796(2), b=16.6048(11), c=29.5659(10) Å, β=94.636(4)°, V=12623(2) ų, Z=8. Refinement led to a final conventional R₁ value of 0.128 for 12428 reflections and 1473 parameters. The resorcinarene displays the usual bowl-type shape, with four hydroxyl protons involved in intramolecular hydrogen bonds, whereas the remaining four make hydrogen bonds with four bridging nitrate ions, which results in the formation of infinite chains. Those chains are arranged so as to form layers, between which the triethylammonium ions and the remaining nitrate ions are hydrogen-bonded one to another.     

Kinetic and Mechanistic Study of the Thermal Decomposition of Ethyl Nitrate

Thermal decomposition of ethyl nitrate (ENT; CH₃CH₂ONO₂) has been studied in a low‐pressure flow reactor combined with a quadrupole mass spectrometer. The rate constant of the nitrate decomposition was measured as a function of pressure (1–12.5 Torr of helium) and temperature in the range 464–673 K using two different approaches: from kinetics of ENT loss and those of the formation of the reaction product (CH₃ radical). The fit of the observed falloff curves with two‐parameter expression provided the following low‐ and high‐pressure limits for the rate constant of ENT decomposition: k ₀ = 1.0 × 10⁻⁴ exp(−16,400/T ) cm³ molecule⁻¹ s⁻¹ and k _∞ = 1.08 × 10¹⁶ exp(−19,860/T ) s⁻¹, respectively, which allow to reproduce (via above expression and with 20% uncertainty) all the experimental data obtained for k ₁ in the temperature and pressure range of the study. It was observed that the initial step of the thermal decomposition of ethyl nitrate is O–NO₂ bond cleavage leading to formation of NO₂ and CH₃CH₂O radical, which rapidly decomposes to form CH₃ and formaldehyde as final products. The yields of NO₂, CH₃, and formaldehyde upon decomposition of ethyl nitrate were measured to be near unity. In addition, the kinetic data were used to determine the O–NO₂ bond dissociation energy in ENT: 38.3 ± 2.0 kcal mol⁻¹.     

Fe-Doped CoS2 Nanoarrays: Efficient Electrocatalytic Nitrate Reduction to Ammonia under Ambient Conditions

The electrocatalytic nitrate reduction reaction (NO₃⁻RR) enables the reduction of nitrate to ammonium ions under ambient conditions. It was considered as an alternative reaction for the production of ammonia (NH₃) in recent years. In this paper, we report that the Fe doping CoS₂ nanoarrays can effectively catalyze the formation of NH₃ from nitrate (NO₃⁻) under ambient conditions. This is mainly due to the increase of the NO₃⁻ reaction active site by Fe doping and the porous nanostructure of the catalyst, which greatly improves the catalytic activity. Specifically, at −0.9 V vs. RHE, the NH₃ yield rate (R_NH3) of Fe−CoS₂/CC is 17.8×10⁻² mmol h⁻¹ cm⁻² with Faraday Efficiency (FE) of 88.93 %. Besides, such catalyst shows good durability and catalytic stability, which provides the possibility for the future application of electrocatalytic NH₃ production.     

Oxidative Coupling of 1,3-Dicarbonyl Compounds by Cerium(IV) Ammonium Nitrate

A fast, mild, and highly efficient method for the intermolecular coupling of 1,3-dicarbonyl compounds using cerium ammonium nitrate in CH₃CN/CH₃OH/H₂O has been described. The procedure provided a convenient method for the synthesis of 1,4-diketone derivatives with excellent yields (up to 96%) and powerful evidence for the oxidation mechanism mediated by cerium ammonium nitrate.