Nitric Acid Solution Research Articles

Extraction of Actinides and Lanthanides(III) from Nitric Acid Solutions with Mixtures of N-(Diphenylphosphoryl)-N'-propylureas with ω-Nitrogen-Containing Groups and Dinonylnaphthalenesulfonic Acid

Extraction of uranium, thorium, and lanthanide(III) ions from nitric acid solutions with mixtures of dinonylnaphthalenesulfonic acid and N-(diphenylphosphoryl)-N'-n-propylureas containing imidazolyl, diethylamino, pyrid-2-yl, and 2-oxopyrrolidine fragments has been studied in organic solvents. Considerable synergetic effect on extraction of metal ions with mixtures of dinonylnaphthalenesulfonic acid and N-(diphenylphosphoryl)-N'-[3-(2-oxopyrrolidino)propyl]urea has been revealed. Stoichiometry of extracted complexes has been determined. Effect of extractant strucuture, organic diluent nature, and HNO3 content in aqueous phase on extraction efficiency of metal cations into organic medium has been accessed.

Extraction of Actinides and Lanthanides(III) from Nitric Acid Solutions with Mixtures of N-(Diphenylphosphoryl)-N'-propylureas with ω-Nitrogen-Containing Groups and Dinonylnaphthalenesulfonic Acid

Extraction of Actinides and Lanthanides(III) from Nitric Acid Solutions with Mixtures of N-(Diphenylphosphoryl)-N'-propylureas with ω-Nitrogen-Containing Groups and Dinonylnaphthalenesulfonic Acid

Extraction Properties of 4-[(Hexylsulfanyl)methyl]-3,5-dimethyl-1-phenyl-1H-pyrazole in the Palladium(II) Recovery from Nitric Acid Solutions

Extraction Properties of 4-[(Hexylsulfanyl)methyl]-3,5-dimethyl-1-phenyl-1H-pyrazole in the Palladium(II) Recovery from Nitric Acid Solutions

Nitrogen recovery from sludge centrate by membrane contactor: Influence of operating parameters and cleaning conditions

In urban wastewater treatment, the sludge generated is treated by anaerobic digestion, to be subsequently dehydrated by centrifuges. Currently, the liquid fraction obtained in this dehydration process is recirculated at the head of the treatment plant. However, its high nitrogen and phosphorus content makes it an effluent with high added value. The recovery of these nutrients could be an excellent alternative for the production of fertilizers or other industrial applications. In this study, the use of a liquid-liquid phase membrane contactor is presented as a favorable solution for the recovery of ammoniacal nitrogen from sludge centrated. The polypropylene hollow fiber membrane was evaluated considering its ammonia removal and recovery capacity. For this, different parameters were evaluated: the influence of the type and concentration of the acid solution, the wastewater pH, the flow rates of feeding and the acid stripping solution, and the contact time. Results showed that with a contact time of 65 min, ammonia removal and recovery percentages of the order of 90% were achieved. The flow rates of the stripping and feed solutions together with the acid concentration did not have a significant influence on the removal but on the recovery. Concerning used acid, sulphuric and phosphoric acid solutions achieved better results than nitric acid solution. The most critical parameter was the pH, obtaining the highest removal and recovery of ammonium at the highest pH. Finally, a stable cleaning protocol was obtained, between preventive and moderate cleanings to avoid severe cleanings, keeping the membrane at its maximum capacity.

Thermal stability of nitric acid solutions of acetohydroxamic acid

Thermal stability of nitric acid solutions of acetohydroxamic acid

INVESTIGATION OF EUDIALYTE CONCENTRATE DECOMPOSITION BY SORPTION CONVERSION IN NITRIC AND HYDROCHLORIC ACID MEDIA

The influence of the sorption conversion conditions for the eudialyte concentrate in low-concentration nitric and hydrochloric acid solutions (concentration and consumption of acid, temperature and duration of the process, sorbent consumption) on the valuable metals extraction efficiency (zirconium, hafnium, niobium, rare earth elements, titanium, manganese) into sulphocationite was studied. Optimal conditions for the process have been determined. It has been shown that sorption conversion in nitric acid solutions is more effective for separating valuable components from the silica component of eudialyte concentrate compared to both the traditional method decomposition by nitric acid and the method of sorption conversion in sulfuric and hydrochloric acid environments. The reasons for the loss of valuable metals and the behavior of natural radionuclides are discussed.

Synthesis and extraction properties of 4,5-diphosphorylated triazoles

A method for the synthesis of 4,5-diphosphorylated 1,2,3-triazoles has been developed, and the extraction of U(VI), Th(IV), and lanthanides(III) from nitric acid solutions by them was studied. A synergistic effect was found in the extraction of metal ions with mixtures of 4,5-diphosphorylated 1,2,3-triazoles and dinonylnaphthalenesulfonic acid. The stoichiometry of the extracted complexes was determined, and the influence of the structure of the extractant and the concentration of HNO3 in the aqueous phase on the efficiency of the extraction of metal ions into the organic phase was considered. It was established that 4,5-diphosphorylated 1,2,3-triazole with the octyl substituent at nitrogen atom has the highest extraction ability with respect to actinides and lanthanides in nitric acid media.

MODIFICATION OF THE SURFACE OF COPPER ALLOYS WITH ALUMINUM IN THE CONDITIONS OF SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS

The influence of the technological parameters of the SHS process (temperature, holding time and alloying of B, Cr, Ti) on the corrosion resistance of brass with a surface alite layer, which effectively resists β-radiation, was studied. The research was carried out in 30% aqueous solutions of HNO3, HCl, H2SO4. Aluminized coatings doped with silicon, which are obtained under optimal parameters, have 1.7-2.1 times higher corrosion resistance than doped B and Ti. Alloyed coatings have phases CuSi, CuAl, CuAl2, CuTi, Ti2Cu3, CuCr, Cu3Al, Cu2Al, Al3Si, and α-phase doped with Cr, Al, Si, B, Ti. When tested in a 30% aqueous solution of nitric acid, the coating doped with titanium and silicon shows a weight loss of 32 and 37 g/m2, respectively.

The Growth Process and Photocatalytic Properties of h-MoO3 and α-MoO3 under Different Conditions

In this experiment, we investigated the effects of different reactions on the growth process and morphology of h-MoO3 and α-MoO3, and their optical properties and photocatalytic activities were also investigated. Orthogonal experiments were designed to investigate the effects of four influencing factors, namely the amount of ammonium molybdate tetrahydrate (AHM), the type of acid, the reaction temperature and the holding time, on the morphology of h-MoO3 by a microwave hydrothermal method. The phase and morphology were analyzed by using advanced physicochemical techniques. The XRD results showed that the samples produced by the microwave hydrothermal method had sharp diffraction peaks, high crystallinity and complete crystalline shape. AHM generates h-MoO3 in both hydrochloric and nitric acid environments. In particular, when the temperature rises to 200 °C, the generated h-MoO3 will be converted to α-MoO3 in a nitric acid environment, which will be generated in a sulfuric acid environment. Therefore, increasing the reaction temperature will result in the conversion of h-MoO3 to α-MoO3 in sulfuric acid solution. SEM results show that the sample prepared from hydrochloric acid solution has a complete hexagonal prism morphology, while the sample prepared from sulfuric acid solution presents a long fibrous morphology, and the sample prepared from nitric acid solution has many defects on the surface of the hexagonal prism morphology. Interestingly, sample A11 prepared in nitric acid solution showed a spherical structure. Since the generated A3, A6 and A9 samples are all stable phase α-MoO3, they have a wider band gap compared with other samples. Their particle size is up to the nanometer scale, so they have strong adsorption properties. The spherical sample A11 has excellent adsorption and photocatalytic activity.

Experimental Study on the Chemical Resistance of Polyaroxydiazole Fiber

Polyarylene oxadiazole fiber (POD) is a kind of fiber commonly used in high temperature resistant filter materials. It is used in industrial filter screens. In order to study its chemical corrosion resistance, this paper uses different mass fractions of sulfuric acid, nitric acid, sodium hydroxide and ammonia solution is used to treat the POD fibers for different times. By characterizing the mechanical properties of the treated fiber, it intuitively reflects the acid and alkali resistance of the POD fibers. The results show that the strength retention rate of POD fibers is 38% when treated with 50% sulfuric acid for 72 hours; the strength retention rate is 36% when treated with 60% nitric acid for 72 hours; the strength retention rate is 77% when treated with 30% sodium hydroxide for 72 hours and after 72 hours of treatment with 20% ammonia water, its strength retention rate is 79%; the alkali resistance of POD fibers is better than the acid resistance.

Selective Complexation and Separation of Uranium(VI) from Thorium(IV) with New Tetradentate N,O-Hybrid Diamide Ligands: Synthesis, Extraction, Spectroscopy, and Crystallographic Studies.

An unmet challenge in the thorium-uranium fuel cycle is the efficient separation of uranium from thorium. Herein, two new tetradentate N,O-hybrid ligands, N,N'-diethyl-N,N'-di-p-tolyl-2,2'-bipyridine-6,6'-dicarboxamide (Et-Tol-BPDA) and N,N'-diethyl-N,N'-di-p-tolyl-2,2'-bipyrimidine-4,4'-dicarboxamide (Et-Tol-BPymDA), comprising a bipyridine or bipyrimidine core and amide moieties were designed and synthesized for selectively complexing and separating U(VI) from Th(IV). The high U(VI)/Th(IV) extraction selectivity was achieved by Et-Tol-BPDA (SFU/Th = 33 at 3 M HNO3) and Et-Tol-BPymDA (SFU/Th = 73 at 3 M HNO3) in nitric acid solutions. The extraction process for U(VI) or Th(IV) with these two ligands primarily proceeded through the solvation mechanism, as evidenced by slope analyses. Thermodynamic studies for the extraction of U(VI) and Th(IV) revealed a spontaneous process. Results from UV-vis spectroscopic titration and slope analyses demonstrated that U(VI) and Th(IV) each form a 1:1 complex with the two ligands both in the monophasic organic solution and the biphasic extraction system. The stability constants of the 1:1 complexes of Et-Tol-BPDA or Et-Tol-BPymDA with U(VI) were found to be larger than those with Th(IV), which coincide well with the high U(VI)/Th(IV) extraction selectivity. The solid-state structures of Et-Tol-BPDA, Et-Tol-BPymDA, and 1:1 complexes of the two ligands with U(VI) or Th(IV) were analyzed by X-ray diffraction technique. The results from this work implicate the potential of bipyridine- and bipyrimidine-derived diamide ligands for uranium/thorium separation.

Transform waste straw into water-holding fertilizer: A targeted modification strategy of functional groups

The goal of this study was to enhance the utilization of millet straw and endow it with the fertilizer function through modifying the carboxymethylcellulose (CMC-NH4), based on wheat straw, by acidification and ammonification to improve water and fertilizer efficiency. Amine group was introduced through the electrophilic substitution to supply nutrients to crops. The order of influential factors on the water absorption property was determined by an orthogonal experiment and showed that the highest water absorbency of 224.7 g/g, which was achieved for the conditions of 3:1 carboxymethylcellulose to nitric acid solution (mass percentage concentration of 50%), 3:1 carboxymethylcellulose to ammonia solution with the mass percentage concentration is 30%. The CMC-NH4 was characterized by scanning electron microscopy, fourier-transform infrared, x-ray diffraction, and X-ray photoelectron spectroscopy techniques, and the results indicated that application of CMC-NH4 promoted the growth indexes of wheat, improved wheat yields. Therefore, the waste straw was modified into the soil conditioner with specific function by the group targeted modification strategy. In addition, the fertilizer efficiency and water-retention behavior of CMC-NH4 encouraged its use as a safe water- and fertilizer-retaining agent in agricultural applications.

Катионообменное выделение америция при анализе природных вод альфа-спектрометрическим методом

The chromatographic method for isolating americium on a single column with KU-2-8 cation exchange resin from nitric acid solutions is proposed for determination of 241Am in natural waters. The advantages of this simple and rapid procedure are the availability and low cost of equipment, reagents and materials and a small amount of waste. Electrolytic deposition of americium is carried out on stainless steel disks from a solution of ammonium chloride and EDTA-Na2 for 30 minutes. Losses are controlled by the internal standard 243Am. The radiochemical recovery of americium was 60–84% for the model samples, including water with high salinity.

INVESTIGATION OF MODIFIED CEDAR NUT SHELL-BASED SORBENTS

The investigation was carried out to establish influences of thermal, chemical and thermochemical modifications on compositions of functional groups of the sorbents based on nut shells of the Siberian cedar (Pinus sibirica) and their physical and chemical properties. Samples of natural cedar nut shells (CNS) were thermally-modified at T=300 °С and analyzed by the methods of potentiometric titration and Fourier-transform infrared spectroscopy. It has been established that thermally-modified CNS possess 1.5–1.7 and 2.3–4.3 times as many hydroxyl and carboxyl groups in the constitution of sorbents grading 0.1–0.5 and 0.55–0.75 mm, respectively, as natural CNS. Chemical modification was carried out in nitric acid solutions with various concentrations (0.5–5n). It has been shown that being treated with 5n HNO3, the samples grading 0.55–0.75 mm possess 3.5 times as many carboxyl groups as natural CNS, while the samples grading 0.1–0.5 possess an increased number of hydroxyl groups only. Thermochemical modification was carried out in 2 stages: first, firing at a temperature of 300 °С, then chemical modification in HNO3 solutions with various concentrations. It has been revealed that this modification results to increasing predominantly hydroxyl groups in the constitution of carbon sorbents. The isotherm of sorption of copper (II) ions by the samples of modified CNS describes microporous solids with a relatively small outer surface, whereas the sorption isotherm of zinc (II) ions describes polymolecular adsorption onto both porous and macroporous adsorbents. The investigation has revealed that the sorbents being chemically and thermochemically modified with 5n nitric acid are most effective to extract copper ions.

Effect of Temperature on the Thermodynamics of the Stepwise Dissociation of Alanyl-Phenylalanine in Aqueous Solutions

The heats of interaction between alanyl-phenylalanine and solutions of nitric acid and potassium hydroxide at 288.15 and 308.15 K and solution ionic strengths of 0.5, 0.75, and 1.0 are determined via calorimetry with KNO3. Standard thermodynamic characteristics (ΔrH°, ΔrG°, ΔrS°, ΔC∘pΔ∘) of the reactions of acid–base interaction in aqueous solutions of alanyl-phenylalanine. The effect temperature has on the heats of dissociation of alanyl-phenylalanine is considered along with the relationship between the thermodynamic characteristics of the dissociation of the dipeptide and the structure of this compound.

Patterns of the process of starch nitration with nitric acid

The article presents the results of the experimental study on the starch nitration process with aqueous solutions of nitric acid. This nitrating medium has a number of advantages over the nitric and sulfuric acids mixture commonly used in industry, in particular it concerns the chemical stability of resulting starch nitrate. The aim of this work is to establish the dependence of nitration degree of starch on the nitration process parameters, taking into account changes in the chemical composition of its macromolecules. The experimental research method involved the use of ferrous sulfate method to determine the nitration degree of starch and IR-Fourier spectroscopy to analyze the macromolecules chemical composition. The parameters of the nitration process were changed in the following ranges: the mass fraction of water in acid solution of 0 to 35%, the temperature of 3.4 to 800С, the nitration module, as the ratio of the mass of the acid solution to the mass of potato starch of 1 to 40, and the nitration time of 1 to 180 min or 24 h. Based on the experimental results, it was found that the maximum degree of starch nitration is achieved with a water mass fraction in the nitrating solution of about 2%; a further increase in its content leads to a decrease in the starch nitration degree. The increase in the starch nitration degree to the maximum value in this case indicates the nucleophilic mechanism of starch nitration. It is shown that the temperature has a weak effect on the starch nitration degree, and nitrates of oxidized starch are formed under the conditions of high temperature. Increasing the nitration modulus leads to an increase in the starch nitration degree. The effect of nitration time on the starch nitration degree is related to the starch property to dissolve in nitric acid. The initial stage of starch nitration process proceeds at a high rate, which is a consequence of the acid intense penetration into the starch amorphous regions and their dissolution. In the following stages, the nitration process is slowed down due to the acid diffusion into the starch crystalline regions. If nitration is continued, a practically stable value of the nitration degree is achieved in the resulting starch nitrate. The obtained results allow choosing rational conditions for preparation of starch nitrate, which is a powerful explosive.

Cover Feature: Gamma Radiation‐Induced Degradation of Acetohydroxamic Acid (AHA) in Aqueous Nitrate and Nitric Acid Solutions Evaluated by Multiscale Modelling (ChemPhysChem 5/2023)

The Cover Feature represents acetohydroxamic acid degradation in used nuclear fuel reprocessing cycles, where it is broken down by hydrolysis and radiation in aqueous nitric acid to form acetic acid, hydroxylamine, nitrous oxide, and hydrogen gas. Designed by Rett Longmore. More information can be found in the Research Article by Jacy K. Conrad, Gregory P. Horne and co-workers.

Chemical recycling of high-density polyethylene (HDPE) wastes by oxidative degradation to dicarboxylic acids and their use as value-added curing agents for acrylate-based materials

Plastic waste has become a serious pollution problem due to the material's high consumption volume and durability. Therefore, effective waste treatment and conversion technology are urgently required. In this work, a chemical recycling process has been developed to convert high-density polyethylene (HDPE) from post-consumer milk bottles to value-added chemicals, especially mixed diacids with high succinic acid content, via hydrothermal nitric acid oxidation. The results reveal that HDPE can be completely recycled into water-soluble compounds with a yield ranging from 15 to 70% (∼8–36% carbon recovery) at 180–200 °C for 2–4 h. The oxidized products examined by 1H NMR spectroscopy are a mixture of succinic acid (C4), glutaric acid (C5), and adipic acid (C6), whose compositions are strongly governed by the reaction temperature, reaction time, filling capacity, nitric acid concentration and the HDPE/nitric acid ratio. With 20 ml of 0.18 g/ml nitric acid solution (1/7.2 HDPE/nitric acid ratio), a maximum product yield (%carbon recovery) of 69% (35%) with C4:C5:C6+ ratio of 55:30:15 (mol%) is achieved at 180 °C for 3 h. When the filling capacity was increased from 40 to 60% by adding extra water at the same HDPE: nitric acid ratio, prolonging the reaction time for 1 h resulted in the products with a high succinic acid composition (>94%) and 75% yield (36% carbon recovery). The benefits of employing dilute nitric acid solutions with the same HDPE: nitric acid ratio on the selectivity of succinic acid is also confirmed by a reaction at 200 °C for 2 h. As oxidation typically occurs at a higher rate at a higher temperature, the maximum product yield (∼53–56%) is received at 200 °C for 2 h. This lower optimum yield obtained at higher reaction temperature and higher nitric acid concentration implies heterogeneous degradation due to limited diffusion of reactive molecules. By adjusting the HDPE: nitric acid ratio (1:3.6 to 1:10.8), the optimum content of nitric acid is in a range of 3.6x–5.4x. The as-received products are successfully developed as UV-curable acrylate precursors by esterifying their carboxylic groups with hydroxyethyl acrylate, using 5 mol% p-toluene sulfonic acid as a catalyst. UV-cured sheets obtained after irradiating under a UV lamp for 10 min have a gel fraction of 80–90% tested in toluene, chloroform, and ethanol.

Dephosphorization of nitric acid solutions from the leaching of monazite ferrous ores under hydrothermal conditions by selective precipitation of iron(III) hydroxyphosphate (giniite)

The precipitation of phosphoric acid as a hydroxyphosphate from nitric acid solutions in the presence of iron(III) oxides and hydroxyoxides under hydrothermal conditions was studied. It was shown that the dephosphorization process proceeds with the formation of iron(III) hydroxyphosphate (giniite) Fe5(PO4)4(OH)3∙2H2O. The most efficient and speedy process is implemented at temperatures of 180–200 °C and above. It was found that the concentration of phosphoric acid in the solution as a result can be reduced to 0.001 mol/L and below. Lanthanide, uranium, and thorium nitrates are stable under conditions of hydrothermal dephosphorization of solutions, in contrast to iron(III) nitrates decomposing to hematite and nitric acid. The features of the studied hydrothermal process were used to increase the efficiency of direct nitric acid leaching of monazite iron-bearing ores of the Chuktukon rare metal deposit.

Development of a kinetic model of magnetite leaching

The object of the research is the process of magnetite leaching with nitric acid solutions, and the subject of the research is the mathematical justification of the kinetic model and the calculation of kinetic parameters. The article considers the case of leaching in the kinetic region, while magnetite is considered as a polydispersity material of spherical shape. It is proposed to use the distribution function of the number of particles N by their radius r in the form N=a∙rb, where a and b are constants. This distribution was used to derive the equation for the rate of the process W, taking into account the change in the surface of the particles depending on the degree of leaching α: W=dα/dτ=K*∙(1–α)m∙((С0(γ–α)/γ))n, where K* is the rate constant; m and n are the order of solid material and nitric acid, respectively; C0 and γ are the initial concentration of nitric acid and its stoichiometric excess. The order m is defined as m=(b+2)/(b+3), at b→∞ the order m→1. When b=0, m=2/3 is the case of the equation for a shrinking sphere. An algorithm for calculating kinetic parameters in the Excel is proposed. Experimental dependences of the degree of transformation α on time τ are approximated by a third-order equation; by differentiating the obtained equation, the values of the velocity Wexp=dα/dτ at individual points are calculated. After the logarithm of the above equation, there is the expression (γ=1): ln(Wexp)=ln(K*)+m∙ln(1–α)+n∙ln(С0(1–α)). With the help of the «LINEST» function in Excel, for a temperature of 373 K, the values of the order of m=0.93 and n=1.29 and the rate constant K*=0.08 were obtained. Calculation of kinetic parameters for different temperatures takes into account the dependence of the rate constant on temperature: ln(Wexp)=lnk0–E/R∙1/T+m∙ln(1–α)+n∙ln(C0(1–α)). As a result of the calculations, the values n=0.83; m=1.2; E/R=–10402; lnk0=25.09 were obtained. The value of the multiplier k0=exp(lnk0)=7.88∙1010, the activation energy E=–8.31∙E/R=86440 J/mol, the total reaction order n+m=2.03 was calculated. The obtained kinetic parameters were used to determine the calculated values of the rate W. The average relative error between the experimental and calculated values of the leaching rates is 10 %. The proposed method of processing experimental data using a mathematical leaching model can be used for any leaching process.