The phase system CaO-CO(NH2)2-N2O5-H2O at 25°C

Isotherms in the acidic region of the phase system CaO-CO(NH)₂-N₂O₅-H₂O at 25°C were determined. In this region, CO(NH₂) · HNO₃ occupies the largest field of the diagram with small encompassing fields for CO(NH₂)₂, Ca(NO₃)₂ · 4CO(NH₂)₂, Ca(NO₃)₂ · 4H₂O, Ca(NO₃)₂ · 2H₂O, and Ca(NO₃)₂.     

Solubility in system CO(NH2)2-NH4NO3-H3PO4-H2O

Solubility data were obtained in the system CO(NH₂)₂-NH₄NO₃-H₃PO₄-H₂O at 0° and 15°C. The results show that high-analysis solution fertilizers can be produced from standard urea-ammonium nitrate (UAN) and phosphoric acid materials. These acidic solution fertilizers contain up to 35% total plant nutrient (TPN = N + P₂O₅ + K₂O), with N:P₂O₅ ratios varying from 20:1 to 1.5:1. Potential liquid products having fertilizer grades of 23-12-0, 26-9-0, 28-6-0, and 31-3-0 are feasible.     

Synthesis of double pyrophosphates of sodium and chromium for pigmentation of organosilicate coatings

The conditions for synthesis of double pyrophosphate of sodium and chromium in the Cr(NO₃)₃-Na₄P₂O₇-H₂O system have been considered. The characteristic properties of organosilicate coatings of the “polyorganosiloxane-layered hydrosilicate-Cr₂O₃-rutile” composition with a finely dispersed green pigment synthesized have been determined.     

Solubilities in the ammonium thiosulfate-urea-ammonium nitrate-water system at 0°C

Solubilities in the system CO(NH₂)₂-NH₄NO₃-(NH₄)₂S₂O₃-H₂O were obtained at 0°C and pH values between 6.12 and 7.33. The new composition of matter, (NH₄)₆(S₂O₃)₂(NO₃)₂·CO(NH₂)₂, was identified and characterized chemically and microscopically. Stable high-analyses solution fertilizers can be produced at 0°C utilizing waste ammonium thiosulfate solutions with standard ammonium nitrate and urea fertilizer materials. A 31-0-0-5.6S grade (%N-%P₂O₅-%K₂O-Other) fertilizer solution can be formed at 0°C when NH₄NO₃/CO(NH₂)₂ is about one. Stable 30% total nitrogen solutions containing up to 10% sulfur can be produced at other NH₄NO₃/CO(NH₂)₂ ratios.     

Low-temperature anti-icing reagents in the Ca(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-Mg(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-CO(NH<Subscript>2</Subscript>)<Subscript>2</Subscript>-H<Subscript>2</Subscript>O system and their properties

The polytherms of ice melting in sections of the Ca(NO₃)₂-Mg(NO₃)₂-CO(NH₂)₂-H₂O system with different component ratios were studied in the temperature interval from 0 to −40°C. A series of nitrate and nitrate-carbonate reagents that are promising for the creation of anti-acing reagents were found, which form eutectics with ice at temperatures from −25 to −39°C. Their properties, viz., melting properties with respect to ice and corrosiveness on metals and alloys, were determined. An effective corrosion inhibitor was selected.     

Reaction products of triammonium pyrophosphate in different Indian soils

Studies were undertaken on the isolation and identification of reaction products of triammonium pyrophosphate (TPP), the major non-orthophosphate constituent of ammonium polyphosphate newly introduced in India, in representative soils of the alfisol, oxisol, entisol, mollisol and vertisol groups of India. Saturated solution of TPP were reacted with soils for periods of 30 minutes and one day with corresponding precipitation times of 15 days, three months and one year to isolate reaction products which were identified by X-ray diffraction technique, infra-red spectroscopy and chemical analyses. Six reaction products, namely, Ca(NH₄)₂P₂O₇ · H₂O, Mg(NH₄)₂P₂O₇ · 4H₂O, Ca(NH₄)₄H₂(P₂O₇)₂, Ca₃(NH₄)₄H₆(P₂O₇)₄·3H₂O, FeNH₄P₂O₇ and NH₄Al_0·33 Fe_0·67P₂O₇ were identified in different soils; Ca(NH₄)₂P₂O₇·H₂O and Mg(NH₄)₂P₂O₇ · 4H₂O occurring in abundance in most soils. Significant hydrolytic degradation of pyrophosphate reaction products to orthophosphate was not observed.Complementary studies where TPP in solid form was applied to soil, and reaction formed at and around the site of TPP placement were identified after six weeks incubation also showed the formation of Ca(NH₄)₂P₂O₇ · H₂O and Mg(NH₄)₂P₂O₇ · 4H₂O in the soils examined.     

Effect of precipitants during the preparation of Cu-ZnO-Al2O3/Zr-ferrierite catalyst on the DME synthesis from syngas

The synthesis of dimethyl ether (DME) from biomass-derived model synthesis gas has been investigated on Cu-ZnO-Al₂O₃/Zr-ferrierite bifunctional catalysts. The catalysts are prepared by co-precipitation–impregnation method using Na₂CO₃, K₂CO₃ and (NH₄)₂CO₃ as the precipitants. The catalytic activity tests reveal that the best yield of DME can be obtained on the catalyst precipitated by using (NH₄)₂CO₃. Detailed characterization studies conducted on the catalysts to measure their properties such as surface area, acidity by temperature-programmed desorption of ammonia (NH₃-TPD), reducibility of Cu oxide by temperature-programmed reduction (TPR), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and copper surface area and particle size measurements by N₂O titration method. Increasing the number of moderate acidic sites and facilitation of easily reducible copper species with small particle size are found to be the prime reasons for the superior functionality of the (NH₄)₂CO₃ precipitated catalyst. The usage of (NH₄)₂CO₃ also leaves no residual ions, whereas the presence of residual K⁺ and Na⁺ ions in the case of K₂CO₃ and Na₂CO₃ precipitated catalysts leads to lower activity and selectivity.     

Transformations of ortho- and pyrophosphates with or without zinc in chemical solutions and major Indian soils

Studies on the formation and identification of the nature of reaction products formed with zinc and ortho- and pyrophosphate fertilizers were carried out in chemical solutions and in contrasting Indian soils having wide pH range from acidic to alkaline. Triammonium pyrophosphate (TPP), a constituent of the newly developed ammonium polyphosphate (APP) and diammonium orthophosphate (DAP), the only orthophosphate fertilizer manufactured and used in the country were taken for these studies. The reaction products (precipitates) formed in the solutions were isolated and identified through X-ray diffraction technique and chemical analysis, and those formed at the sites of fertilizer placement separated and identified only through X-ray diffraction technique. In the study with solutions ZnNH₄PO₄ (orthorhombic) was identified at all levels of Zn applications and at both concentrations of 0.1Mg and 1.0M DAP; whereas, Zn₃(NH₄)₂(P₂O₇)₂.2H₂O was observed only at the lower concentration (0.1 M) of TPP with Zn. Zinc was completely soluble at the higher concentration (1.0M) of TPP indicating the formation of a soluble complex, (NH₄)₆Zn(P₂O₇)₂.6H₂O. In soils, the reaction products obtained with band application of DAP alone and along with Zn fertilizers were CaHPO₄.2H₂O, Ca(NH₄)₂(HPO₄)₂.H₂O (dimorph B), MgNH₄PO₄.6H₂O (struvite), MgHPO₄.3H₂O, FePO₄.2H₂O (metastrengite, monoclinic), AlPO₄.2H₂O (orthorhombic), ZnNH₄PO₄ (orthorhombic) and Zn₃(PO₄)₂.4H₂O. The reaction products with TPP alone and with Zn were Ca(NH₄)₂P₂O₇.H₂O, Mg(NH₄)₂P₂O₇.4H₂O (monoclinic), FeH₂P₂O₇, Ca₂P₂O₇.2H₂O (monoclinic) and Zn(NH₄)₂P₂O₇.H₂O.     

An Aerosol Chemical Reactor for Coating Metal Oxide Particles with (NH4)SO4-H2SO4-H2O. 1. New Particle Formation

In situ atmospheric measurements (notably single-particle mass spectrometry) show that tropospheric aerosols are internally mixed, including both water-soluble and insoluble components. This fact notwithstanding, most process study laboratory work has concentrated on water-soluble electrolytes because the generation of particles composed of both soluble and insoluble components is difficult to achieve in the laboratory. Even so, such an aerosol is essential for accurate process studies of atmospheric aerosols and for the quantitative calibration of single-particle mass spectrometers. In the completed work, particles composed of a (NH₄)₂SO₄-H₂SO₄-H₂O coating on a TiO₂, Al₂O₃, or ZrO₂ core are prepared in a novel chemical reactor, which is a tube furnace with a linear-temperature gradient along its longitudinal axis. Reactor controls on the number size distribution are reported, including the linear flow velocity, the SO₃ vapor pressure, the NH₃ vapor pressure, the reactor temperature gradient, and the presence or the absence of insoluble seed nuclei (viz. TiO₂, Al₂O₃, and ZrO₂).     

Thermal decomposition of ammonium sulphate

The thermal decomposition and vaporisation of ammonium sulphate, (NH₄)₂SO₄, is shown to take place via two distinct sets of reactions. In the first, ammonium pyrosulphate, (NH₄)₂S₂O₇, is the primary condensed phase product: 2(NH₄)₂SO₄ ← (NH₄)₂S₂O₇+2NH₃+H₂O The second stage concerns the decomposition of the pyrosulphate. Ammonia, sulphur dioxide, nitrogen and water are the major products, the dominant reaction being 3(NH₄)₂S₂O₇ ← 2NH₃+6SO₂+2N₂+9H₂O     

五元体系KCl-KBr-K2SO4-K2B4O7-H2O 323 K和348 K的相平衡

用等温溶解平衡法研究了五元体系KCl-KBr-K₂SO₄-K₂B₄O₇-H₂O在323 K和348 K时的相平衡关系,测定了该五元体系在相应温度条件下平衡溶液的溶解度和密度,根据相平衡实验数据绘制相应的相图(K₂SO₄饱和)。研究结果表明:该五元体系在323 K和348 K条件下均属于固溶体型,相图中均有2个平衡固相结晶区,其平衡固相分别为固溶体K(Cl,Br)和K₂B₄O₇·4H₂O,1条单变量曲线。该五元体系323 K和348 K的相图相比,348 K时K₂ B₄O₇·4H₂O结晶区变小,而固溶体K(Cl,Br)结晶区变大。     

Phase Equilibria in Water-Salt Systems Consisting of Potassium,Sodium, and Ammonium Carbonates and Anti-Icing Properties of Carbonate Compositions

Phase equilibria in K₂CO₃–H₂O, Na₂CO₃–H₂O, K₂CO₃–Na₂CO₃–H₂O, K₂CO₃–(NH₄)₂CO₃–H₂O systems under temperatures ranging from 0 down to ?36°C are investigated. The carbonate compositions forming low-temperature eutectics are revealed. Their melting ability with respect to ice under temperatures ?5 and ?10°C is determined. It was found that potassium carbonate is characterized by sufficient anti-icing properties. Potassium carbonate composition activity is determined with respect to metals. Efficient corrosion inhibiters are selected. It was found that potassium carbonate is aggressive with respect to cement concrete. Special protection is necessary, if potassium carbonate is used on cement concrete coatings.     

Formations of a nonanuclear peroxo molybdate and its heptanuclear precursor

Coupling reaction of peroxo heptanuclear and dinuclear molybdenum complexes K₆[Mo₇O₂₂(O₂)₂]·9H₂O (1) and K₂[Mo₂O₃(O₂)₄(H₂O)₂]·2H₂O (2) results in the formation of a nonanuclear peroxo molybdate K₈[Mo₉O₂₅(O₂)₆]·9H₂O (3) in a weak acidic solution, which is promoted by the existence of lactic acid. The activation of peroxo group in compound 3 shows obvious O–O bond activation in comparison with 1, which is based on structural data and infra-red analyses.     

A tetranuclear oxofluorovanadium(IV) cluster encapsulating a Na(H2O)n+ subunit

Hydrothermal reactions of sodium vanadate, methylenediphosphonic acid, hydrogen fluoride and the appropriate organoamine yielded the vanadium(IV)-oxyfluoride compounds [NH₃(CH₂)₂(NH₂)(CH₂)₂NH₃]₃[{Na(H₂O)} ⊂ {V₄O₄F₂(O₃PCH₂PO₃)₄}]·8H₂O (1·8H₂O) and [NH₃(CH₂)₂(NH₂)(CH₂)₂(NH₂)(CH₂)NH₃]₂[{Na(H₂O)} ⊂ {V₄HO₄F₂(O₃PCH₂PO₃)₄}]·7H₂O (2·7H₂O). The vanadium-oxyfluoride cationic unit {V₄O₄F₂(O₃PCH₂PO₃)₄}^10 − of the compounds consists of pairs of fluoride bridged {VFO₅} octahedra linked through η⁴-diphosphonate ligands into a three polyhedra thick band. The {Na(H₂O)_n}⁺ groups occupy the interior of the band but are displaced from the centroid toward one face so as to project the aqua ligands into the extra-annular domain. The fluoride ligands bridge two vanadium sites as well as coordinating to the sodium cation.     

Easy-care properties of simultaneously grafted and crosslinked cotton fabrics

The Concurrent grafting of acrylic acid (AA) and crosslinking of dimethylodihydroxyethyleneurea (DMDHEU) with cotton fabric in the presence of ammonium persulfate [(NH₄)₂S₂O₈)], magnesium chloride hexahydrate (MgCl₂ · 6H₂O), and ammonium chloride (NH₄Cl) catalysts were studied. These salts were separately used or as a binary mixture of (NH₄)₂S₂O₈/MgCl₂ · 6H₂O or (NH₄)₂S₂O₈/NH₄Cl. The pad–dry–cure method was employed for the fabric treatment under a variety of conditions. The latter include the nature and kind of the single catalyst as well as pair-mixed catalysts, the concentrations of the catalyst and AA, and temperature and duration of curing. The effects of these conditions on the values of the carboxyl content and crease recovery angle (CRA) of the treated fabrics were evaluted. The tensile strength, elongation at break, dyeability, aqueous and nonaqueous oily soiling, and soil-release properties of the treated fabrics were also examined. Results obtained indicated that all treated fabrics have superior properties, except tensile strength and elongation at break, as compared with the untreated fabric (control). However, beside the AA-grafting and DMDHEU-crosslinking reactions, there are other types of reactions catalyzed by the salts used, viz., the addition reactions between AA molecules and the cellulosic hydroxyls The tentative mechanisms for these reactions are suggested. © 1996 John Wiley & Sons, Inc.     

Thermal Analysis of Ammonium Dinitramide Decomposition

The new energetic material ammonium dinitramide (ADN), NH₄N(NO₂)₂, has been investigated with regard to its thermal properties and decomposition behavior. Thermal decomposition of ADN is observed after complete melting at 91.5 °C. The main decomposition pathway is based on the formation of NH₄NO₃ and N₂O followed by the thermal decomposition of NH₄NO₃ to N₂O and H₂O at higher temperatures. Side reactions forming NO₂, NO, NH₃, N₂ and O₂ are described and a mechanism for the acid-catalized decomposition of hydrogen dinitramide, dissociation product of ADN, is proposed.     

Voltammetric study of electrocatalysis for dioxygen reduction by trinuclear rutheniumammine complex confined in a polymer membrane

Electrocatalytic O₂ reduction was studied using a modified electrode coated with a Nafion membrane (Nf) dispersing a trinuclear ruthenium ammine complex ([(NH₃)₅Ru^IIIORu^IV(NH₃)₄ORu^III(NH₃)₅]Cl₆, Ru-red). When measuring cyclic voltammogram under O₂ atmosphere (at 0.5 mV s⁻¹), catalytic currents due to O₂ reduction were found to develop below −0.2 V (vs. Ag/AgCl). Since Ru-red undergoes irreversible decomposition into the mononuclear complexes via the reduced state (Ru^III-Ru^III-Ru^III) (∼−0.1 V), it is suggested that the electrocatalysis originates from the decomposed species (initial active species: Ru^II(NH₃)₅(OH₂) and Ru^II(NH₃)₄(OH₂)₂) rather than from the Ru-red. Although the present electrocatalyst was also applied to H₂O₂ reduction system, the catalytic activity was found to be poor from the voltammetric behavior. It appeared that the kinetics of the electrocatalysis is much faster in the O₂ reduction than in the H₂O₂ one. A selective and direct catalysis for O₂ reduction into H₂O was suggested from a ring-disk voltammogram to take place by an aggregate of the mononuclear ruthenium complexes in the polymer matrix. In addition, it was found that electrocatalytic O₂ reduction involves a slow kinetic process, so that factors affecting the overall kinetics were discussed in terms of the catalysis mechanism.     

Bubble-point measurements in the ammonia-carbon dioxide system

The bubble-point pressures in the NH₃-CO₂ system, at complete chemical equilibrium, have been measured in the range of 130–185°c corresponding to pressures of 30–175 atm. The NH₃-CO₂ system exhibits a sharp pressure minimum; in the area of high NH₃ concentration, critical behaviour and retrograde condensation have been found. The results, as part of the NH₃-H₂O-CO₂ system, are discussed from the standpoint of chemical phase theory and are shown to be consistent with the NH₃-H₂O and CO₂-H₂O systems. The relation of these measurements to the commercial urea synthesis is also discussed.     

Synthesis of K2O–MgO–SiO2 compounds as slow-release fertilisers from acid-leached biotite residues

For the utilisation of mineral residues and improving the nutrient use efficiency in fertilisers, the K₂O–MgO–SiO₂ compounds prepared as slow-release K fertilisers by using the acid-leached biotite residues, K₂CO₃, and Mg(OH)₂ as the starting materials were systematically studied and evaluated in this work. Sintering experiments were performed at 700–1000 °C and solubility experiments were conducted by dissolving the sintered samples in 0.50 M HCl solution, 0.10 M citric acid solution, and water. The results showed that K₂MgSiO₄ (KMS), KMS-K_1.14Mg_0.57Si_1.43O₄(K₂M₂S₅)–K₂MgSi₃O₈(KMS₃) mixtures, and K₂MgSi₅O₁₂ (KMS₅) were synthesised at 800 °C, 850–900 °C, and 950 °C, respectively. These compounds are citrate-soluble, and the solubilities followed the order KMS > K₂M₂S₅ ≫ KMS₃ > KMS₅. The release properties of the K₂O accumulated in water for all the K₂O–MgO–SiO₂ compounds fit the release kinetics Elovich equations, which suggest that KMS and KMS-K₂M₂S₅-KMS₃ can be used as slow-release K fertilisers and that KMS₅ with a much slower release of K₂O may be more suitable as a soil conditioner. Evaluation of the raw materials, synthesis approach, product properties, and environmental benefits shows that K₂O–MgO–SiO₂ slow-release fertilisers are eco-friendly and offer plenty of advantages with regard to soil fertility, environmental protection, resource utilisation, and energy consumption.     

Development of potassium ferrate(VI) cathode material stabilized with yttria doped zirconia coating for alkaline super-iron battery

To improve the stability of potassium ferrate(VI) (K₂FeO₄) cathode and its properties of charge transfer in alkaline battery system, K₂FeO₄ cathodes are coated by yttria (Y₂O₃) doped zirconia (ZrO₂) composites, denoted as Y₂O₃–ZrO₂ composite coatings. These composite coatings are derived from the conversion of yttrium nitrate (Y(NO₃)₃·6H₂O) and Zirconium oxychloride (ZrOCl₂·6H₂O) in ether medium. Examinations by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) show that K₂FeO₄ cathodes are coated by Y₂O₃–ZrO₂ overlayer. Alternatively, results of discharge properties and electrochemical impedance spectroscopes (EIS) indicate that when the molar ratio between Y₂O₃ and ZrO₂ is 0.09, denoted as Y₂O₃ (9 mol%)–ZrO₂, the stability and charge transfer of Y₂O₃ (9 mol%)–ZrO₂ coated K₂FeO₄ cathodes are improved greatly compared to that of uncoated or ZrO₂ coated K₂FeO₄ cathodes. Therefore, Y₂O₃–ZrO₂ composite coatings are a potential choice to improve the stability and charge transfer of K₂FeO₄ cathodes in alkaline electrolyte.