Ammonium Dihydrophosphate Research Articles

Obtaining phosphate fertilizer with additional nutrients

In order to obtain phosphorus fertilizer enriched with additional nutrients, the decomposition process of apatite concentrate with sulfuric acid was carried out with an additive, in the first variant – ammonium hydrophosphate, and in the second variant - ammonium and potassium hydrophosphates. Experimental studies have studied the effect of additives on the interaction of sulfuric acid with fluorapatite, as well as X-ray phase and IR spectroscopic analyses have studied the structural composition of the resulting product. It was found that with the use of additives, the resulting phosphorus fertilizer contains, along with calcium dihydrophosphate, also ammonium dihydrophosphate. A distinctive feature is the decomposition of sulfuric acid phosphates, resulting in a poorly soluble calcium sulfate that passes into the solid phase, which has traces of its presence in the resulting fertilizer, and may also not be part of the solution. The process of decomposition of fluorapatite with sulfuric acid using an additional part (NH4)2HPO4, the optimal amount of the additional part should be considered 12-18% (by weight of sulfuric acid) additive, while the highest degree of decomposition of apatite concentrate is achieved, which is 95-97%. The conducted studies have established that the introduction of an additive - ammonium and potassium hydrophosphates - into the process of sulfuric acid decomposition of apatite concentrate also has a positive effect on the duration of the superphosphate maturation period. To clarify the structural composition of the finished product, X–ray phase studies and IR spectrometric analysis of the powdered product were carried out. Thus, mineral fertilizers obtained with the use of additives having an additional nutrient element in their composition, namely nitrogen - in the first variant, and nitrogen and potassium - in the second variant.

Properties of potassium dihydrogen phosphate and its effects on plants and soil

Abstract One of the challenges of the modern world is to improve human nutrition and to safely increase the yield of agricultural production using existing agricultural land. It is clear that sufficient agricultural efficiency cannot be achieved without fertilizers, but fertilizers must cause minimal damage to the soil. Microorganisms, such as spore-forming bacteria, actinomycetes, fungi, algae, and protozoa play an important role in the soil and keep soil healthy. One of the soil substances involved in reactions that take place in plants is cellulose. This study investigated the effect of potassium dihydrogen phosphate (PDP), synthesized (via conversion between potassium chloride and ammonium dihydrophosphate) and granulated with the addition of microcrystalline cellulose (MC), on plants (winter wheat Toras, Lithuania) and soil microorganisms. The data of plants fertilized with pure KH2PO4, ones fertilized with PDP granulated with MC, and grown without fertilizers were compared in this study. Scanning electron microscopy and differential scanning calorimetry analysis were used to characterize the obtained product. One-way analysis of variance was used to evaluate the differences of the mean values between groups. In all cases, the significance level was p ≤ 0.05. The effect of pure KH2PO4 on plant indicators was found to be lower than that of granular PDP with MC. The length of the leaves was 29.63 and 31.20 cm, green mass was 0.471 and 0.763 g, ash mass was 0.015 and 0.019 g, respectively. In addition, granular PDP with MC did not adversely affect the soil microorganisms because the number of any species of bacteria (Spore b., mineral nitrogen assimilating bacteria, cellulose degrading bacteria) did not decrease and a slight increase in the number of Actinomycetes (from 8.5 × 105 to 2.9 × 106 KSV/g) and molds (from 3.0 × 104 to 1.4 × 105 KSV/g) was observed. The granular PDP with MC that we developed and used have better physical properties, higher agrochemical efficiency and cause less harm to soil microorganisms compared to pure PDP.

Исследование свойств твердофазных электродных материалов на основе фосфата лития – ванадия

An original method for the synthesis of lithium-vanadium phosphate has been developed, which includes two stages: 1st — heat treatment of a mixture of vanadium oxide and ammonium dihydrophosphate; 2nd — mechanical activation of a mixture of the product obtained at the first stage with lithium hydroxide on Bridgman equipment, followed by heat treatment, and providing a 95 % product yield in a highly dispersed state. It is shown that electrodes based on synthesized Li3V2(PO4)3 are reversibly cycled in the basic 1C mode. Optimization of the ratio of the electrode components showed that its maximum characteristics are achieved with the following ratio between the components: 82 % Li3V2(PO4)3: 10 % carbon black : 8 % solid polymer electrolyte. Solid-phase electrodes based on lithium-vanadium phosphate surpass known analogues with liquid electrolyte in capacity, stability and persistence.

Synthesis of Promising Cathode Material for Lithium Polymer Batteries

Original method for synthesis of lithium vanadium phosphate was developed. The method includes two stages: 1st, synthesis of iron phosphate from a mixture of ammonium dihydrophosphate and metal oxide; and 2st, synthesis of lithium vanadium phosphate by thermal lithiation of the product obtained in the 1st stage, with mechanical activation of the precursor in the course of plastic deformation. Our results would provide some basis for further improvement on the Li3V2(PO4)3 electrode materials for advance lithium-ion batteries.

Hydrothermal synthesis of urchin-like alumina for fire-extinguishing powders

Alumina with an urchin-like morphology has been synthesized from Al2(SO4)3/CO(NH2)2/H2O/isopropanol mixture via hydrothermal route followed by calcination. Raman spectra and SEM images have shown the urchin-like structure to be formed of γ-AlOOH phase with the component ratio Al3+/CO(NH2)2/H2O = 1:(2–3):(100–200). The increase in CO(NH2)2 content has resulted in the formation of needle-like crystals of NH4Al(OH)2CO3. Structural transformations of alumina during hydrothermal synthesis have been investigated by SEM and TEM methods. The 5–10 μm urchin-like alumina particles have been found to be composed of 100–200-nm-thick sheets. The alumina samples have been studied by low-temperature nitrogen adsorption method. The adsorption–desorption isotherms and pore size distributions have shown that pore structure of the urchin-like alumina is formed by the slit pores with two open ends. It has been found that after treatment with chlorosilanes the surface of the urchin-like alumina becomes superhydrophobic, the average contact and sliding angle values being 154° and 5°, respectively. Addition of 5 wt% of the hydrophobized urchin-like alumina particles to the model fire-extinguishing powder has made the powder hydrophobic, the average contact angle being increased up to 151°. Introduction of 5 wt% of the hydrophobized urchin-like alumina particles to ammonium dihydrophosphate has resulted in a decrease in the cohesion strength for ammonium dihydrophosphate fire-extinguishing powder from 0.415 to 0.104 kPa. The hydrophobized urchin-like alumina particles can be used as functional additives to the fire-extinguishing powders for the improved flowability and water repellency to be achieved.

Study of X-ray diffraction processes in ADP crystals under the influence of temperature gradient

The influence of temperature gradient on the intensity of X-ray beam reflected from atomic planes of antiferroelectric crystal of ammonium dihydro-phosphate (ADP) was studied. It was found that under the influence of temperature gradient on ADP crystal, the intensity of diffracted X-ray beam initially decreases at small values of gradient and then monotonously increases with increasing gradient. It is assumed that in the initial period of the action of temperature gradient the crystal domains have no time to orient in the same direction, and the intensity of beam decreases owing to the scattering of X-rays in different directions when reflected from the walls of boundaries of domains. After the alignment of domains, their arrangement in the same direction, separate areas of unidirectional domains are formed under the action of temperature gradient and the intensity of diffracted X-ray beam increases, as confirm the experimental data. The specified mechanism is supposed to occur also in other crystals having the domain structure.

Refractory Porous Materials Based on Secondary Resources and Phosphate Compounds

Results are provided for a study of porous ceramic materials prepared in the course of chemical and exothermic reactions based on a system containing secondary resources (chamotte scrap, mullite-containing waste, aluminum smelting slag), aluminium phosphate binder, aluminum refractory clay, and various additives. Temperature dependences are established for heat capacity and thermal conductivity in the range 30 – 1000°C for the material obtained. It is shown that the optimum overall aluminum and slag content in a mixture for preparing porous materials is 10 – 20%. It is established that addition of magnesite and chrome-magnesite, and also ammonium dihydrophosphate, makes it possible to control density and strength of the materials obtained.

DTA-TG and XRD study on the reaction between ZrOCl2·8H2O and (NH4)2HPO4 for synthesis of ZrP2O7

In this paper, we report results of thermoanalytical investigation on the reaction between ZrOCl2·8H2O and (NH4)2HPO4 in molar ratio 1:2. Differential thermal-thermogravimetric and X-ray diffraction analyses were performed in order to reveal the chemical transformations, which took place during heating of the individual compounds ZrOCl2·8H2O, (NH4)2HPO4 and the mixture ZrOCl2·8H2O:2(NH4)2HPO4. It was shown that the transformations in the mixture below 160 °C were connected with dehydration of ZrOCl2·8H2O and interaction between the components of the mixture, which resulted in the formation of NH4Cl, NH4H2PO4 and a mainly amorphous zirconium phase, most likely t-ZrO2. The zirconium component subsequently reacted with ammonium dihydrophosphate (below 200 °C) or with dehydrated phosphate derivatives (above 200 °C), which in both cases yielded an amorphous product. The interaction between the components of the mixture resulting in the formation of ZrP2O7 was completed by its crystallisation at 610 °C. Our study indicates an alternative low-temperature approach for the synthesis of the technologically important ZrP2O7 material.

Mechanism of LiFePO4 solid-phase synthesis using iron (II) oxalate and ammonium dihydrophosphate as precursors

An experimental study of the thermolysis mechanism of FeC2O4, NH4H2PO4, Li2CO3, and citric acid from the viewpoint of the usage of a mixture of these compounds in lithium power engineering for the solid-state synthesis of LiFePO4 and its composite with carbon LiFePO4/C as well as comparison of experimental data with thermodynamic calculations were made in the temperature range from 25 up to 1,000 °C. The oxides Fe3O4, Fe2O3, and FeO were detected as the intermediate products of thermolysis of ferrous oxalate in these conditions. Various paths of oxalate decomposition may well proceed concurrently with the predomination of this or that path under slight changes in the experimental conditions. The formation of orthorhombic lithium phosphate Li3PO4 is detected just in a blend grinded at room temperature, and Li3PO4 and NH4PO3 are the basis of triphylite synthesis at increased temperatures (up to 800 °C). A new phase of single-substituted anhydrous lithium citrate C6H7O7Li is formed at room temperature if citric acid C6H8O7∙H2O is used as an organic precursor. The thermal treatment, at which citric acid can form a carbon coating with a maximum conductivity, was estimated experimentally. To identify the products of chemical reactions, structural characterization, and comparative analysis of samples synthesized at several temperatures, a set of techniques was used, namely TG with gas release analysis, Mossbauer spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, surface microanalysis, laser diffraction analyses. Galvanostatic cycling was used to study the electrochemical properties of the LiFePO4/C electrode material.

Thermodynamics of LiFePO4 Solid-Phase Synthesis Using Iron(II) Oxalate and Ammonium Dihydrophosphate as Precursors

A detailed thermodynamic analysis and an experimental study of the thermolysis mechanism of Li2CO3 + NH4H2PO4 + FeC2O4 blends were performed from the viewpoint of the usage of these compounds for the LiFePO4 solid-phase synthesis. Thermodynamic calculations of the assumed chemical reactions have been done within a practically important (for LiFePO4 synthesis) temperature range of (25 to 900) °C. The thermodynamic parameters of the related compounds (Li2O, Li3PO4, (NH4PO3)4, NaFePO4, FePO4 2H2O, FePO4, and LiFePO4) were determined more precisely than earlier. The temperature dependences of changes in the standard Gibbs energy, standard enthalpy, standard entropy, and standard molar heat capacity for the chemical reactions in LiFePO4 synthesis were calculated. Various paths of oxalate decomposition may well proceed concurrently with the predomination of this or that path under slight changes in the experimental conditions. The formation of orthorhombic lithium orthophosphate Li3PO4 was detected just in a blend grinded at room temperature. Heating up to 360 °C results in full destruction of the reaction mixture; Li3PO4 in its activated state is a crystal component at this synthesis stage. Lithium orthophosphate structurally belonging to the same spatial Pnma group as the target product LiFePO4 is the basis of its synthesis.

Synthesis and electrochemical properties of lithium iron phosphate

Original method for synthesis of lithium iron phosphate was developed. The method includes two stages: 1st, synthesis of iron phosphate from a mixture of ammonium dihydrophosphate and metal oxide; and 2nd, synthesis of lithium iron phosphate by thermal lithiation of the product obtained in the 1st stage, with mechanical activation of the precursor in the course of plastic deformation.

A time-resolved luminescence spectroscopy study of self-trapped excitons in NH 4H 2PO 4 crystals

A complex investigation of the dynamics of electronic excitations and luminescence in nonlinear optical crystals of ammonium dihydrophosphate NH 4H 2PO 4 was performed using low-temperature vacuum ultraviolet luminescence spectroscopy with time resolution upon selective photoexcitation by synchrotron radiation. Data on the photoluminescence (PL) decay kinetics, time-resolved PL spectra (2–6.2 eV), and time-resolved PL excitation spectra (4–24 eV) were obtained for the first time for NH 4H 2PO 4 crystals at 8 K. It is ascertained that the PL of NH 4H 2PO 4 crystals in the vicinity of 4.7 eV has intrinsic character due to the radiative annihilation of self-trapped excitons. Possible channels of generation and decay of relaxed and unrelaxed electronic excitations in NH 4H 2PO 4 crystals are discussed.

Synthesis of [NZP]-Structure-Type Materials by the Combustion Reaction Method

Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}P{sub 6}O{sub 24} and Ba{sub 1.25}Zr{sub 4}P{sub 5.5}Si{sub 0.5}O{sub 24} compositions, which belong to the [NZP] family of low-thermal-expansion materials, were synthesized by the combustion reaction method using urea as a fuel and NH{sub 4}NO{sub 3} as an oxidizer. The combustion method is a highly exothermic reaction often referred to as self-propagating high-temperature synthesis. The raw materials used were metal zirconates and fine ZrO{sub 2} powders. An earlier-described combustion method using metal nitrates, zirconium oxynitrate, and ammonium dihydrophosphate to synthesize [NZP] compounds was modified in the present study by replacing these costly raw materials with less-expensive oxides. The reactivity of different combinations of raw materials also is discussed.

Low-temperature time-resolved vacuum UV spectroscopy of NH4H2PO4 crystals

A complex investigation of the dynamics of electronic excitations in nonlinear optical crystals of ammonium dihydrophosphate NH4H2PO4 was performed using low-temperature vacuum UV luminescence spectroscopy with time resolution upon selective photoexcitation by synchrotron radiation. Data on the photoluminescence decay kinetics, time-resolved photoluminescence spectra (2–6.2 eV), and time-resolved photoluminescence excitation spectra (4–24 eV) were obtained for the first time for NH4H2PO4 crystals at 8 K. It is ascertained that the photoluminescence of NH4H2PO4 crystals in the vicinity of 4.7 eV has intrinsic character due to the radiative annihilation of self-trapped excitons. Possible channels of generation and decay of relaxed and unrelaxed electronic excitations in NH4H2PO4 crystals are discussed.