2CO3 Solution Research Articles

Effect of annealing temperature and precipitation agent on the structure, optical and magnetic characteristics of dysprosium orthoferrite nanoparticles

Powders consisting of DyFeO3 nanoparticles were obtained by the co-precipitation method using two different precipitating agents (NaOH (SH) and (NH4)2CO3 (AC) solutions) and followed by annealing for 1 h at 850, and 950 °C. Properties of the synthesized samples were characterized by FT-IR, PXRD, BET, TEM, UV-Vis DRS, and VSM analyses. The obtained data revealed that both calcination temperature and precipitation agent had notable influence on the structural parameters and properties of the synthesized DyFeO3 nanoparticles. Increasing the calcination temperature led to the increase of structural characteristics such as average crystallite size (DScher, DW-H, DRietveld, nm), lattice cell volume (V, Å), and crystallite phase content as well as in properties such as band gap energy value (Eg, eV), coercivity (Hc, Oe), remanent magnetization (Mr, emu∙g−1), and net magnetization (Mn, emu∙g−1). Additionally, when comparing samples calcined at the same temperature, DyFeO3-AC exhibited higher structural, optical, and magnetic properties compared to DyFeO3-SH. Moreover, the DyFeO3 nanoparticles synthesized in this study exhibited lower band gap energy (1.87–1.93 eV), coercivity (0.018–0.023 Oe), and remanent magnetization (2.82∙10−6–3.87∙10−6 emu∙g−1) values, but larger net magnetization (2.43–2.62 emu∙g−1) when compared to RFeO3 perovskites synthesized by different methods (R = La, Y, Ho, Dy, Eu, Tb).

Dissolution of contaminant Zr-DBP and corrosion of stainless steel by dissolved solution

In the nuclear spent fuel reprocessing, zirconium dibutyl phosphate (Zr-DBP) is deposited on the surface of stainless steel equipment, making spent fuel reprocessing difficult. Therefore, in this study, hydrazine carbonate ((N2H5)2CO3) was used to dissolve Zr-DBP. The effects of solid–liquid ratio, different mass fractions of (N2H5)2CO3 solutions, and (N2H5)2CO3 solutions containing different concentrations of hydrogen peroxide (H2O2) on the dissolution of Zr-DBP were investigated. The corrosion rates of different dissolution solutions on stainless steel were also investigated. When the mass fraction of (N2H5)2CO3 in solution was increased from 1 % to 20 %, the concentration of Zr(IV) at dissolution equilibrium increased from 1.05 g/L to 1.61 g/L, respectively. When the dissolution temperature was kept in the range of 25 °C to 65 °C, the increasing temperature promoted the dissolution of Zr-DBP. The presence of H2O2 induced the production of the white precipitates zirconium hydroxide (Zr(OH)4). In addition, the corrosion rate of stainless steel gradually increased from 0.00153 mm/a to 0.0138 mm/a when the concentration of H2O2 in the (N2H5)2CO3 solution was increased from 0 M to 1.5 M. The dissolution ability of Zr-DBP in different carbonate solutions was (N2H5)2CO3 ≥ ammonium carbonate ((NH4)2CO3) > sodium carbonate (Na2CO3) ≥ potassium carbonate (K2CO3).

Trypsin Digestion Pretreatment of Kelp Samples and the Iodine Speciation Analysis of Iodate, Iodide, MIT, and DIT by HPLC-ICP-MS

The analysis of iodine content in kelp is mainly focused on determining total iodine content, which lacks a rapid and sensitive analytical method for iodine species corresponding to iodate, iodide, monoiodotyrosine (MIT), and diiodo-tyrosine (DIT). Based on exploring the pretreatment methods of enzymatic hydrolysis of kelp, a rapid determination method of high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for different iodine species existed in kelp samples was established. The pretreatment method is trypsin hydrolysis of kelp samples treated at 50°C for 10 hours, then the extraction solution was obtained by centrifugation, and filtration was proved for the first time. A high-efficiency separation anion-exchange column (Dionex IonPac AS-14) for iodate, iodide, MIT, and DIT with 0.1 mol·L−1(NH4)2CO3 solution at pH = 9 as a mobile phase, a flow rate of 0.8 mL·min−1 for the first 1500 s, and 1.2 mL·min−1 for the last 1800 s was confirmed. The linear ranges of the standard calibrations on four iodine species are 1.0–150 μg·L−1, and the detection limits are 1.62, 1.02, 1.59, and 2.55 μg·L−1, respectively, while the RSD values of four iodine species are all less than 2%. Under the optimized conditions, the proposed method was successfully applied for the speciation analysis of iodine in kelp samples.

Influence of Synthetic Conditions on the Crystal Structure, Optical and Magnetic Properties of o-EuFeO3 Nanoparticles

In this paper, powders consisting of o-EuFeO3 nanoparticles were obtained by the co-precipitation method using two different precipitating agents (NH3 and (NH4)2CO3 solutions; corresponding products were denoted as samples S.1 and S.2, respectively) and followed by annealing for 1 h at 750, 850, and 950 °C. The magnetic, optical, and physicochemical characteristics of S.1 and S.2 were evaluated by means of EDXS (energy dispersive X-ray spectroscopy), PXRD (powder X-ray diffraction), TG/DSC (thermogravimetry/differential scanning calorimetry), FTIR (Fourier-transform infrared spectroscopy), TEM (transmission electron microscopy), UV-Vis DRS (Ultraviolet–Visible diffuse reflectance spectroscopy), and VSM (vibrating-sample magnetometry). The o-EuFeO3 structure was shown to be stable at annealed temperatures, and t = 850 °C is recommended for synthesizing such substances. The average size of o-EuFeO3 crystals is around 27 (S.1) and 34 nm (S.2). The results revealed a homogeneous distribution of the main elements on the samples’ surfaces, with morphology consisting of isometric and highly agglomerated nanoparticles. The bandgap value (Eg) of the synthesized samples was 2.31 (S.1) and 2.39 eV (S.2). Besides, these nanoparticles appeared to possess paramagnetic behavior.

Separation of Cu impurity from spent lithium-ion batteries by roasting in air and leaching with (NH4)2CO3 solution of low concentration

Separation of Cu impurities from spent lithium-ion batteries (LIBs) before precipitating other valuable metals is critical to improve the quality of final products. Currently, the main process for separating Cu impurity from spent LIBs by extraction and precipitation has the disadvantage of being high cost and complicated process. In this work, the surface characteristics of spent LIBs materials before and after thermal treatment are explored, and the effects of the concentration of ammonium salts, temperature, and pulp density on the leaching of Cu impurity are investigated. The novel process proposed in this work removes Cu impurities from spent LIBs materials using a solution of (NH4)2CO3 at low concentration. The results suggest that organics on the spent LIBs surface can be effectively removed by heating at a temperature of 505 °C to avoid the influence of organics on the removal of Cu impurities. Furthermore, the results of the leaching experiment demonstrate that (NH4)2CO3 displays an excellent leaching effect on Cu compared to NH4Cl, (NH4)2SO4, and NH4HCO3. The leaching efficiency of Cu at the concentration of 0.25 mol/L (NH4)2CO3, temperature 80 °C and leaching time of 120 min reaches 99.1%. On the contrary, the leaching efficiencies of Ni, Co, and Mn are <4% on average. The thermodynamic analysis proves the potential for removing Cu impurities from spent LIBs materials using a solution of (NH4)2CO3 at low concentration. The process lays the foundation for the subsequent hydrometallurgical process to recover other metals.

Separation of Hf(IV) from Zr(IV) in thiocyanate medium with ionic liquid Aliquat 336

Solvent extraction is the key technical link for the preparation of nuclear-grade Hf and Zr for advanced nuclear reactors. In this study, the separation of Hf(IV) over Zr(IV) from the highly concentrated aqueous feed by solvent extraction with ionic liquid Aliquat 336 was investigated. The results indicated that thiocyanate forms of the ionic liquid dissolved in amyl acetate were more conducive to selective extraction of Hf(IV). Under the selected conditions, optimal extraction efficiency of Hf(IV) could be up to 94.5%. The separation factor of Hf(IV) to Zr(IV) was found to be 19.4. The extraction mechanism of Hf(IV) was revealed by slope analysis and FTIR analysis. The extracted complex of Hf(IV) was determined as [(A336+)12(HfO2+)3(H+)(12x-2)(SCN−)(16+12x)]. The extraction isotherm indicated that nuclear-grade Zr(IV) could be recovered from the raffinate via a two-stage extraction. The sulfuric acid solution showed appreciable selectivity in scrubbing of Zr(IV) from the loaded organic phase. The Hf(IV) species in the remaining loaded organic phase could be effectively stripped by 3.0 M (NH4)2CO3 solution. Accordingly, a recyclable process flowsheet for the separation of Hf(IV) from Zr(IV) using Aliquat 336 was developed. It is believed that this process is a promising way for the preparation of enriched Hf and high purity Zr.

Terahertz absorption characteristics of ammonium salt solution based on self-sampling microfluidic chip

With the continuous development of terahertz (THz) detection technology, the use of terahertz spectroscopy to study chemical samples has become one of the indispensable tools in the field of biochemistry. While most biomolecules biological activity can only be expressed in aqueous solutions, water as a polar molecule has strong absorption properties for terahertz waves, making it difficult to use terahertz technology to study the activity of biological samples in aqueous solutions. In this study, a sandwich-type terahertz microfluidic chip with high terahertz wave transmission was designed and combined with a terahertz time domain spectroscopy (THz-TDS) system to test the terahertz spectra of distilled water, 0.9 mol/L NH4Cl, (NH4)2SO4, (NH4)2CO3 and CH3COONH4 solutions, respectively, and to investigate the effect of the electric field action time on the hydrogen bond in the solution under the action of an external electric field. The experimental results show that the terahertz spectra of different ammonium solutions at the same concentration differ significantly, indicating that the ion hydration process affects the intermolecular hydrogen bonding in water, while the applied electric field also affects the hydrogen bonding in water, resulting in a change in the terahertz waves water absorption.

A H-Bonding and Electrostatic Interaction Combined Strategy for TcO4- Separation by a Nitrotriacetate-Derived Amine-Amide Extractant.

Effective and selective separation of technetium from acidic nuclear liquid waste is highly desirable for partitioning and transmutation but is of significant challenge. Highly efficient extraction of pertechnetate can be achieved by taking H-bonding and electrostatic interaction combined strategy. Base on this strategy, an amine-amide ligand NTAamide(n-Oct) was employed to extract TcO4- in HNO3 solution. Using n-dodecane as a diluent, NTAamide(n-Oct) demonstrated excellent extractability and good selectivity toward TcO4- with a rapid extraction equilibrium that could be reached in less than 1 min. Its maximal loading capacity for TcO4- was almost 100 times as much as that of traditional amine extractant Aliquat-336 nitrate. Meanwhile, TcO4- could be efficiently stripped from the loaded organic phase by (NH4)2CO3 solution. Slope analysis indicated the formation of a 1:1 complex of NTAamide(n-Oct) with TcO4-. The extraction conformed to the anion exchange extraction model, as confirmed by analyses of single-crystal X-ray diffraction, 1H NMR titration, FTIR, and ESI-MS.

Characterization and constitutive modeling of red clay contaminated with ammonium carbonate

AbstractConventionally, red clay is used for agricultural purposes in southern China. Fertilizers, especially urea, are commonly introduced into the red clay to improve the crop yields. However, due to the rapid urbanization in China, large areas of lands with red clays have been converted into sites for domestic and industrial constructions. Nevertheless, few researchers focused on the effect of urea on the strength and compressibility of red clay. In this research, the shear strength and compressibility of the red clay saturated by different concentrations of the (NH4)2CO3 solution (urea's hydrolysates) were experimentally investigated using direct shear as well as oedometer tests, respectively. It was noticed that both the shear strength and stiffness of the red clay significantly decreased after exposure to the urea solution. In addition, the micromechanisms of the strength and compressibility of the red clay treated by the (NH4)2CO3 were studied by the scanning electron microscope test and X‐ray diffraction test. Based on the test results, a new model was developed to simulate the chemomechanical behavior of saturated clayey soil by modifying the Barcelona basic model (BBM) for unsaturated soils. The proposed model introduces four additional parameters, compared to the BBM, to account for the nonlinear shear strength behavior of the red clay. This model accounts for most of the complex features related to the strength and stiffness behavior of clayey soils. The parameter calibration procedures, by using the oedometer and direct shear test results, are also presented. To validate the proposed model, experimental results from the literature are considered in which illite clay samples were either mechanically or chemically or both mechanically and chemically loaded. Part of the experimental results is used to calibrate the model parameters and the other part along with the calibrated parameters is used to verify the proposed model. A comparison between experimental data and predicted results demonstrated that the proposed model is able to capture the main features related to the chemomechanical coupling behavior of saturated soils.

Influence of synthesis conditions on the calcium carbonate microparticle properties obtained by homogeneous and heterogeneous precipitation

CaCO3 microparticles were obtained by chemical precipitation from CaCl2 solution using Na2CO3 or (NH4)2CO3 solutions (heterogeneous precipitation) or carbamide (homogeneous precipitation) as precipitation agents. The effects of various experimental conditions, such as the temperature, duration and reagent ratio on the properties of precipitated CaCO3 were experimentally investigated. It was found that the shape of particles and CaCO3 polymorphs depended on the precipitation agent and process temperature; the size of particles—on the reagent ratio, the precipitation agent and the deposition time. Biphasic calcite-vaterite spherical microparticles with the highest polydispersity coefficient (K = 0.98 with an average particle size ln ≈ 3 μm) were obtained using Na2CO3 solution as a precipitation agent under low temperature (20 °C). Calcite rhombohedral crystals (ln ≈ 3 μm) were obtained using carbamide at high temperature (100 °C). Increasing the temperature of Na2CO3 and (NH4)2CO3 solutions (70–100 °C) led to formation of the biphasic aragonite–calcite druses of needle crystals (druses size ≈ 10–30 μm). Increasing the aging time for sediments in the mother liquor up to 1 h did not affect the shape of CaCO3 particles.

Extraction of nickel and cobalt from a laterite ore using the carbothermic reduction roasting-ammoniacal leaching process

The carbothermic reduction roasting followed by ammoniacal leaching of a Ni-laterite ore from Bajaur (Pakistan) has been studied first time for its potential exploitation via the Caron process. The use of fuel oil as reductant can be costly in Pakistan, therefore, plenty available coal was employed in this study. The roasting parameters like coal mixing proportion (5–15 wt%), temperature (600–900 °C), additive dosage (3–12 wt%), and time (15–180 min) were varied to optimize the selective reduction of Ni and Co. The extent of goethite phase transformation of roasted products characterized through the X-ray diffraction (XRD) analysis could depict sharp peaks for the formation of Ni-Fe alloy phase in the presence of an additive, Na2SO4. The optimal reduction condition was observed to be laterite ore mix with 10 wt% coal and 9 wt% Na2SO4, and roasted at 800 °C for 120 min. Leaching of the roast-reduced product performed in NH4OH–(NH4)2CO3 solutions (150 g/L total NH3) was influenced by carbonate ion concentration and yielded >90% Ni and 67% Co. The apparent activation energy of Ni, 21.2 kJ/mole and Co, 7.6 kJ/mole indicated to follow intermediate-controlled and diffusion-controlled mechanism, respectively. Furthermore, the leach liquor was pre-oxidized and contacted to 10 vol% of LIX 84-I; yielding a selective extraction of >97% Ni over Co at the organic-to-aqueous ratio of 1. Results presented in this paper suggest that the extraction of Ni and Co from Bajaur lateritic ore is technically feasible through the Caron process, and can be useful to others as well.

The kinetics of CO2 indirect mineralization of [formula omitted] to produce [formula omitted

The CO2 mineralization is an economical route to reduce CO2 emission for the production of high-value carbonate products. The performance of CO2 indirect mineralization of MgSO4 by (NH4)2CO3 solution was studied systematically. The effects of process parameters on the reaction performance and morphology of MgCO3·3H2O were investigated. In the reaction process, three stages were observed, including nucleation induction, solid phase growth and equilibrium stage. The nucleation induction period and equilibrium time are shortened with the increase of reaction temperature, initial reactants concentration, stirring speed and (NH4)2CO3/MgSO4 molar ratio. These parameters also play a vital role in the morphology of products. It was found that the difference between crystal growth rate and mass transfer rate has a significant impact on crystal morphology. A kinetic model was derived from the solid phase growth rate. The estimated activation energies of forward and reverse reaction are 30.37 kJ/mol and 32.71 kJ/mol, respectively.

Leaching of synthetic Ca3WO6 with ammoniacal ammonium carbonate solution under atmospheric pressure: A fundamental study

In (NH4)2CO3 solution, leaching Ca3WO6-bearing product converted from tungsten concentrate can directly obtain ammonium tungstate solution, and thus eliminates high-salinity wastewater discharge in ammonium paratungstate manufacture. Possible reactions of Ca3WO6 leaching in aqueous ammoniacal ammonium carbonate solution under atmospheric pressure were investigated thermodynamically and experimentally. The results show that tungsten in Ca3WO6 can be efficiently leached out by forming CaCO3(s) and (NH4)2WO4 (aq) in aqueous ammoniacal ammonium carbonate solution, while raising ratio of total ammonia to total carbon in solution and forming calcite are beneficial to increase the WO3 leaching ratio. Whereas the secondary reactions of Ca3WO6 with H2O and/or Ca (OH)2/CaCO3 with (NH4)2WO4 may occur and thus CaWO4 forms in the leaching, decreasing WO3 leaching ratio especially in concentrated (NH4)2WO4 solution and in case of forming vaterite. In addition, a three-layer cover was observed on the unreacted Ca3WO6 and hinders the leaching process. Through simultaneous grinding and leaching, both high WO3 leaching ratio and high WO3 concentration leachate can be achieved by increasing ratio of total ammonia to total carbon in NH3-(NH4)2WO4- (NH4)2CO3-H2O system. These results are helpful to optimize the leaching process of the converted product with Ca3WO6 by roasting tungsten-containing materials.

Preparation of Double Ammonium-Sodium Paratungstate and Its Transformation to Ammonium Paratungstate

For the circulation of sodium carbonate in treating tungsten concentrate by the autoclave soda leaching, preparation of double ammonium-sodium paratungstate (DASP) from Na2WO4-Na2CO3 solution and its transformation to ammonium paratungstate (APT) were studied experimentally. The result shows that DASP can be obtained by the reaction of CO2-(NH4)2CO3 with Na2WO4-Na2CO3 solution, and almost all of Na remain in the spent liquid, which can be returned to the leaching process of tungsten concentrate. Moreover, the transformation of DASP to APT can be achieved by the reaction of DASP with (NH4)2CO3 or (NH4)2SO4. In (NH4)2CO3 solution, APT can be prepared by hydrothermal reaction at 120°C, but the tungsten conversion ratio is only 63.94% for 6 h. In the (NH4)2SO4 system, irregularly stacked APT and more than 90% of the tungsten conversion ratio can be achieved by hydrothermal transformation, whereas DASP can completely transform to quadrate APT by in situ reaction at 120°C for 6 h. The results presented are conducive to improve the soda leaching method and achieve cleaner, economical, and efficient preparation of APT.

Wet chemical etching of ZnO films using NH x -based (NH4)2CO3 and NH4OH alkaline solution

In this paper, we deposited ZnO thin films by RF magnetron sputtering at room temperature from un-doped targets. Wet chemical etching of ZnO films in (NH4)2CO3 and NH4OH solutions were examined. For comparison, hydrochloric acid was also used as an etchant. The NH x -based alkaline solutions provide well-controlled etching rate, and smooth surface and sidewall profiles. Although NH x -based alkaline solution etch rates for ZnO were relatively low, they were enhanced with the use of a H3O stabilizer. In this case, the NH4OH solution went from reaction-dominant mode to diffusion-dominant mode, which is beneficial for smooth surface morphology.

Molybdenite–limestone oxidizing roasting followed by calcine leaching with ammonium carbonate solution

Oxidizing roasting of molybdenite with lime can significantly reduce SO2 pollution compared with the traditional roasting without lime. However, the calcine is subsequently leached by sulfuric acid, resulting in serious equipment corrosion and abundant non-recyclable CaSO4 slag. In this work, a novel process, in which the molybdenite was roasted with CaCO3 followed by (NH4)2CO3 solution leaching, was proposed to improve the art of lime roasting–sulfuric acid leaching. Oxidizing roasting of molybdenite with CaCO3 was investigated through thermodynamic calculation, thermogravimetric analysis and roasting experiments. The results show that the products of the oxidizing reaction of MoS2 in the presence of CaCO3 and O2 are CaSO4, CaMoO4 and CO2 at 573–1000 K. The MoS2 conversion rate achieves approximately 99% and the sulfur-retained rate attains approximately 95% with a CaCO3-to-MoS2 molar ratio of 3.6 at 500 °C for 1 h by adding 5% mineralizer A (mass fraction). The leaching results show that the leaching rate of Mo reaches 98.2% at 85 °C for 7 h with a (NH4)2CO3 concentration of 600 g/L and a liquid–solid ratio of 10 mL/g. The results presented are potential to develop a novel cleaner technique for ammonium molybdate production.

Indirect mineral carbonation of blast furnace slag with (NH4)2SO4 as a recyclable extractant

Large quantities of CO2 and blast furnace slag are discharged in the iron and steel industry. Mineral carbonation of blast furnace slag can offer substantial CO2 emission reduction and comprehensive utilisation of the solid waste. In this study, a recyclable extractant, (NH4)2SO4, was used to extract calcium and magnesium from blast furnace slag (main phases of gehlenite and akermanite) by using low-temperature roasting to fix CO2 through aqueous carbonation. The process parameters and efficiency of the roasting extraction, mineralisation, and Al recovery were investigated in detail. The results showed that the extractions of Ca, Mg, and Al can reach almost 100% at an (NH4)2SO4-to-slag mass ratio of 3:1 and at 370 °C in 1 h. Adjusting the pH value of the leaching solution of the roasted slag to 5.5 with the NH3 released during the roasting resulted in 99% Al precipitation, while co-precipitation of Mg was lower than 2%. The Mg-rich leachate after the depletion of Al and the leaching residue (main phases of CaSO4 and SiO2) were carbonated using (NH4)2CO3 and NH4HCO3 solutions, respectively, under mild conditions. Approximately 99% of Ca and 89% of Mg in the blast furnace slag were converted into CaCO3 and (NH4)2Mg(CO3)2•4H2O, respectively. The latter can be selectively decomposed to magnesium carbonate at 100–200 °C to recover the NH3 for reuse. In the present route, the total CO2 sequestration capacity per tonne of blast furnace slag reached up to 316 kg, and 313 kg of Al-rich precipitate, 1000 kg of carbonated product containing CaCO3 and SiO2, and 304 kg of carbonated product containing calcium carbonate and magnesium carbonate were recovered simultaneously. These products can be used, respectively, as raw materials for the production of electrolytic aluminium, cement, and light magnesium carbonate to replace natural resources.

Solubility Data in the Ternary NH4HCO3–NH4VO3–H2O and (NH4)2CO3–NH4VO3–H2O Systems at (40 and 70) °C

Effective separation of NH4VO3 from NH4HCO3 or (NH4)2CO3 solution is an important step in the newly proposed vanadium production process based on sodium salt roasting. The solubility data for NH4HCO3–NH4VO3–H2O and (NH4)2CO3–NH4VO3–H2O systems at (40 and 70) °C were studied, respectively; thus, a strategy for effective separation of NH4VO3 from NH4HCO3 or (NH4)2CO3 solution has been proposed.

Experimental investigation of the effect of addition of different activators to aqueous solution of potassium carbonate: Absorption rate and solubility

The absorption rate and solubility of carbon dioxide (CO2) into 35wt% aqueous potassium carbonate (K2CO3) solution in the presence of different promoters were evaluated experimentally. A vapor–liquid equilibrium (VLE) apparatus was used to measure the equilibrium partial pressure of CO2 and CO2 partial pressure changes with time in CO2 partial pressures ranging from 0 to 50kPa (low partial pressures) and at temperature 313.15K. The activators considered are Piperazine (PZ), 2-(1-piperazinyl)-ethylamine (PZEA), Monoethanolamine (MEA), Tetraethylenepentamine (TEPA) and Boric acid (BA). Different molar ratios of the activator to K2CO3 (0.25, 0.66 and 1.5) at constant total blend concentration of 2.5moldm−3 (M) were investigated to find the optimal molar ratio. Among studied promoters, the highest absorption rate and CO2 solubility was achieved with the TEPA+K2CO3 solution with molar ratios of 0.66 and 1.5 respectively. As an overall conclusion, TEPA+K2CO3 solution could be a potential candidate for CO2 capture.

Uranium(VI) extraction from concentrated Egyptian wet-process phosphoric acid using a synergistic organophosphorous solvent mixture

Uranium(VI) recovery from concentrated Egyptian hemi-dihydrate wet-process phosphoric acid, 9.2 M, is investigated using synergistic organophosphorous solvent mixture of dinonyl phenyl phosphoric acid (DNPPA) and tris(2-ethylhexyl)phosphate (TEP). The effect of various factors such as [DNPPA] concentration, [TEP] concentration, phosphoric acid concentration, shaking time, aqueous: organic phase’s ratio (V aq/V org), stability of the solvent, the diluents effect, and temperature on the degree of extraction has been established. The effect of different stripping agents was investigated. The enthalpy change of the uranium extraction process was determined and the extracted uranium is further subjected to a second cycle of extraction [0.3 M D2EHPA + 0.075 M TOPO], scrubbing impurities (5 M sulfuric acid), and finally stripping with 1 M (NH4)2CO3 solution. Precipitation of uranium in highly pure UO3 product using hydrogen peroxide and heat treatment at 375 °C were carried out.