Aqueous Ammonia Solution Research Articles

Carbon nanotubes in high internal phase emulsion polymer composite for packed-cartridge micro-solid-phase extraction of fluoroquinolones in urine

Aim of this study stands in the evaluation of a carbon nanotubes-based polymerized high internal phase emulsion composite (CNT/polyHIPE) as sorptive phase in biological sample preparation. A micro-solid-phase extraction procedure (µSPE) was developed for trace fluoroquinolone (FQ) antimicrobials, namely Ciprofloxacin, Levofloxacin, Lomefloxacin, Moxifloxacin, Norfloxacin and Sparfloxacin, in human urine samples. PolyHIPEs modified by incorporation of different concentrations of nanotubes (0.2–0.8 wt %) were one-pot synthesized and applied in the packed-cartridge setting. The sorption affinity for the drugs was investigated in tap water and buffered aqueous solutions, demonstrating the key role of the nanotubes embedded in the polymer. The 0.5 wt % CNT composite was selected to develop a straightforward µSPE procedure directly in raw urine (1 mL sample), followed by HPLC-MS/MS. Targets were retained on the sorbent at near neutral pH and, after an aqueous washing (0.1 % v/v formic acid), eluted in a single-step with 4 % v/v ammonia aqueous solution (15 % v/v acetonitrile), thus combining extraction and clean-up. The method allowed accurate quantification of FQs, as evidenced by the recoveries (74–116 %, n = 3) obtained on blank pooled urine samples spiked with 40, 75, 150 µg L−1, accompanied by good inter-day precision (RSD < 14 %, n = 3). To confirm the applicability of the analytical method, some real-life blind samples were processed as a proof of concept.

Gamma-Ray-Induced Amino Acid Formation during Aqueous Alteration in Small Bodies: The Effects of Compositions of Starting Solutions.

Organic compounds, such as amino acids, are essential for the origin of life, and they may have been delivered to the prebiotic Earth from extra-terrestrial sources, such as carbonaceous chondrites. In the parent bodies of carbonaceous chondrites, the radioactive decays of short-lived radionuclides, such as 26Al, cause the melting of ice, and aqueous alteration occurs in the early stages of solar system formation. Many experimental studies have shown that complex organic matter, including amino acids and high-molecular-weight organic compounds, is produced by such hydrothermal processes. On the other hand, radiation, particularly gamma rays from radionuclides, can contribute to the formation of amino acids from simple molecules such as formaldehyde and ammonia. In this study, we investigated the details of gamma-ray-induced amino acid formation, focusing on the effects of different starting materials on aqueous solutions of formaldehyde, ammonia, methanol, and glycolaldehyde with various compositions, as well as hexamethylenetetramine. Alanine and glycine were the most abundantly formed amino acids after acid hydrolysis of gamma-ray-irradiated products. Amino acid formation increased with increasing gamma-ray irradiation doses. Lower amounts of ammonia relative to formaldehyde produced more amino acids. Glycolaldehyde significantly increased amino acid yields. Our results indicated that glycolaldehyde formation from formaldehyde enhanced by gamma rays is key for the subsequent production of amino acids.

Recycling of metals from LiFePO4 battery cathode material by using ionic liquid based-aqueous biphasic systems.

Lithium-ion batteries are essential for electric vehicles and energy storage devices. With the increasing demand for their production and the concomitant surge in waste generation, the need for an efficient and environmentally friendly recycling process has become imperative. This work presents a new approach for recycling of metals from the LiFePO4 (LFP) cathode material. The cathode material was first leached by a HCl solution without an oxidizing agent. Subsequently, an ionic-liquid-based aqueous biphasic system (IL-based ABS) was used for the separation of lithium and iron from leachate solutions, followed by a precipitation process. The influence of the acid concentration, solid-to-liquid ratio and leaching time on the leaching yield was investigated. UV-vis absorption spectra revealed the presence of mixed-valent iron in the leachate, with 83 ± 1% Fe(ii) and 17 ± 1% Fe(iii). The ABS systems comprised tributyltetradecylphosphonium chloride [P44414]Cl and a salting-out agent (HCl or NaCl). The extraction percentage of iron reached 90% and less than 1% of lithium was extracted under the studied optimal conditions. Further enhancement of iron extraction, reaching 98%, was achieved via a two-stage cross-current extraction process. Iron was precipitated from the loaded IL phase with an efficiency of 97% as Fe(OH)2 and Fe(OH)3, using an aqueous ammonia solution. Lithium was precipitated as Li3PO4 with a lithium purity of 99.5% by adding K3PO4 solution. The ionic liquid used in the process was efficiently regenerated and used in four extraction cycles with no activity decline, with an extraction percentage of 90% of iron in each cycle.

ОЦЕНКА ЭФФЕКТИВНОСТИ ПОДАВЛЕНИЯ АММИАКА В ВОЗДУШНЫХ СРЕДАХ ПРОИЗВОДСТВЕННЫХ ПОМЕЩЕНИЙ С ИСПОЛЬЗОВАНИЕМ БАРЬЕРНОГО РАЗРЯДА

One of the main problems in the industrial production of livestock and poultry products is the neutralization of toxic gases in the air removed from livestock premises. Ozonation is used for this. Ozone is produced in dielectric barrier discharge installations. The disadvantages of the method include the dependence of the electrical characteristics of the dielectric barrier discharge on the parameters of the medium and the generation of nitrogen oxides. (Research purpose) The research purpose is determining the effectiveness of ammonia suppression by ozone generated in dielectric barrier discharge installations at various parameters of the generator operating mode. (Materials and methods) Established the effectiveness of ammonia suppression by ozone at various parameters of the ozone generator operation mode. A 25 percent aqueous solution of ammonia with controlled purging over the surface of the solution was used as an ammonia source. The dependences of the mass concentration of ozone (O3), nitrogen oxides (NOx) and hydrogen sulfide (H2S) at the generator output on the operating mode parameters were studied. It was shown that the range of changes in the concentration of gases varied within the following limits: ozone - from 180 to 4, ammonia - from 80 to 2, hydrogen sulfide - from 4 to 0, nitrogen oxides - from 0 to 130 milligrams per cubic meter. (Results and discussion) It was found that the concentration of ammonia decreased from 50 to 10 milligrams per cubic meter; the time to reach the specified values of the concentration of ammonia in the stream was 20-50 seconds; when ozone is generated in all operating modes, nitrogen oxides are formed in the weight ratio O3/NOx from 1.42/1 to 1/1. The dependences of the generation of ozone and nitrogen oxides on the input voltage of the generator power supply unit were determined. It was noted that the optimal pumping rate of plasma-forming gas (atmospheric air) ranged from 0.8 to 1.5 m/ s; the mass ratio of nitrogen oxides to ozone varies from 0.69 to 0.98, which is unacceptable for premises with permanent residence of animals and maintenance personnel. (Conclusions) It was stated that the results obtained in assessing the rational operating modes of ozonators allow us to formulate technical requirements for the development of a specialized ozone generator adapted for use in agricultural production.

Obtaining a complex mineral fertilizer from raw materials of varying degrees of purification from impurities

The article is devoted to the synthesis of a complex fertilizer magnesium-ammonium phosphate (MAP) from raw materials of varying degrees of purification, the effect of certain impurities on the MAP yield, as well as the choice of optimal conditions for obtaining this fertilizer. Phosphorus, as is known, is an irreplaceable element of plant nutrition, therefore the introduction of compounds containing phosphorus in one form or another is necessary for the normal development of plants during the growing season. Phosphoric acid, obtained by opening natural phosphates with mineral acids, in particular, sulfuric acid, is often used to obtain phosphoric fertilizers. One of the ways to purify the phosphoric acid obtained in this case is purification using various organic solvents. At the output, phosphoric acid is purified from most impurities, containing a small amount of impurity cations and anions, the main of which are fluorides and sulfates. We carried out the MAP synthesis on the basis of chemically pure phosphoric acid and using an acid purified with an organic solvent tributyl phosphate. It has been shown that the presence of sulfates and fluorides in purified phosphoric acid increases the MAP solubility in an aqueous solution by increasing the ionic strength of the solution and leads to a slight decrease in the yield of the synthesis product from 81% to 78%. The interfering effect of impurity anions can be reduced by conducting the process in an alkaline medium, pH 9-10, with the addition of an excess relative to the stoichiometric amount of an aqueous ammonia solution.

A hybrid forces Quantum Mechanical Charge Field Molecular Dynamics of Cs+ ion in aqueous ammonia: A solvation lability, “structure breaking” phenomenon and hydrogen bond properties

AbstractThe dynamics and structure of Cs+ solvation in an aqueous ammonia solution have been investigated using the Quantum Mechanical Charge Field Molecular Dynamics (QMCF‐MD) simulation method. The system contained 18.6% ammonia in aqueous solution at 298.15 K. The QM region was set to a radius of 7.0 Å to include the first and second solvation shells. The Hartree‐Fock (HF) level was applied to calculate the ion‐ligand and ligand–ligand interactions in the QM region using the LANL2DZ‐ECP basis set for the ion and DZP‐Dunning for the ligands. The radial distribution revealed only one solvation shell, indicating a labile solvation structure. The various coordination number of ligands suggests an instant exchange between them. The mean residence times of 1.29 and 0.9 ps were less than in the pure water and liquid ammonia system, indicating higher mobility ligands of the aqueous ammonia system. The preferential factor 0.55 supports the hypothesis that the Cs+ ion prefers to be dissolved in water. As the ligands moves further away from the ion, the observed number of hydrogen bonds increases, revealing the “structure‐breaking” property of the Cs+ ion. The minimum angle ligand‐ion‐ligand tends to be higher near the ion, confirming this phenomenon.

High-pH mobile phase in reversed-phase liquid chromatography-tandem mass spectrometry to improve the separation efficiency of aminoglycoside isomers.

In chromatography, the use of extreme conditions can often lead to unique separation selectivity. In this study, a highly basic mobile phase (pH > 11), which is not typically employed for reversed-phase liquid chromatography (RPLC), was utilized in RPLC-tandem mass spectrometry (MS/MS) to achieve effective separation between electrically neutral bases of aminoglycosides (AGs). A mixture of AGs was simultaneously analyzed using 500mmol L-1 ammonia aqueous solution (pH 11.8) as the mobile phase. A total of 11 AGs, including 2 stereoisomers of neomycin (B and C) and 5 structurally similar components of gentamicin (C1, C1a, C2, C2a, and C2b), were completely separated for the first time. The high separation performance for AGs was mainly due to two factors: First, slight differences in hydrophobicity among the AGs were significantly enhanced at a high pH by the complete acid dissociation of amines. Second, the high pH of the mobile phase minimized any electrostatic interactions between the AGs and residual silanol groups in the stationary phase, resulting in extremely sharp peaks for the AGs. The sensitivity of spectinomycin decreased by more than 20% when using the highly basic mobile phase (pH 11.8) due to its degradation, therefore, a mixture of 10 AGs was analyzed with 250mmol L-1 ammonia aqueous solution (pH 11.5) with less degradation as the optimum condition. The developed analytical method could be used to determine the concentrations of trace AGs in milk with high accuracy and precision. Thus, RPLC-MS/MS using a high-pH mobile phase has great potential for the efficient separation of basic compounds containing amino sugars such as AGs.

Synthesis of iron oxide nanoparticles encapsulated poly(styrene‐co‐4‐vinyl pyridine) nanocomposites for column adsorption and photocatalytic degradation of para nitrophenol from water

AbstractStyrene (St), 1,4 vinyl pyridine (4VP) monomers and divinyl benzene (DVB) monomer‐cum‐crosslinker at different molar ratios were subjected to emulsion polymerization in the presence of FeCl2, 6H2O/FeCl3⋅4H2O followed by the treatment with an aqueous ammonia solution to produce several iron oxide nanoparticles (IONs) impregnated crosslinked copolymer composites. The resulting polymer metal nanocomposites (PMNCs) were characterized by FTIR, proton and 13C NMR, UV–visible spectroscopy, XRD, XPS, DLS, magnetic properties, SEM and TEM. The PMNCs were used for batch and column adsorption and photocatalytic degradation of p‐nitrophenol (PNP) from water. The PMNC4 composite prepared with an styrene:4VP molar ratio of 5:1 (16.7 mol% 4VP), 4 wt.% DVB crosslinker and 0.025/0.05 molar ratios of Fe(II)/Fe(III) salts leads to an optimum batch equilibrium adsorption (qe, mg/g)/removal% of 496.36/99.3 PNP from aqueous PNP of concentration 100 mg/L. The same composite showed an equilibrium PNP adsorption (qe) of 114.2 mg/g polymer and a removal% of 26.8 for an inlet feed concentration (Ci, mg/L)/flow rate (Qt, mL/min)/bed height (h, mm) of 100/30/30 in a fixed bed. The PMNC4 polymer showed a photodegradation efficiency of 98% with a 1st order rate constant of 0.029 min−1 after 70 min of degradation of 100 mg/L PNP in solar light.Highlights Copolymer network of styrene, 4 vinyl pyridine and DVB were synthesized. Iron oxide nanoparticles were introduced into the network in‐situ during synthesis. The metal polymer nanocomposites (PMNCs) were characterized. Synthesis parameters were optimized with respect to batch adsorption of PNP. PMNCs showed excellent fixed bed adsorption and photocatalytic degradation of PNP.

The [Zn(NH3)4]2+ reactions with quinaldinate or pyrazinoate: A ready synthetic route to zinc(II) coordination polymers?

The reaction of [Zn(NH3)4]2+ in aqueous ammonia solution with quinaldinic acid (quinoline-2-carboxylic acid) gave a mononuclear heteroleptic ammine/quinaldinate complex with the [Zn(quin)2(NH3)] composition. The introduced secondary ligand adopted the usual N,O-bidentate chelating coordination. In the analogous reaction with pyrazinoic acid (pyrazine-2-carboxylic acid), complete substitution of ammonia with pyrazionate and water was observed. A mixture of two compounds formed: a mononuclear and already known [Zn(pyraz)2(H2O)2] and a novel one-dimensional (1D) coordination polymer [Zn(pyraz)2(H2O)]n. X-ray structure analysis revealed the pyrazinoate ligands in [Zn(pyraz)2(H2O)]n in two binding modes, in a bidentate chelating coordination and in a tridentate bridging coordination. The bridging pyrazinoate has engaged in binding three out of four donors: a carboxylate oxygen and both nitrogen atoms. A detailed presentation of the structure of [Zn(pyraz)2(H2O)]n and its comparison with the structures of related compounds are given below.

5-Alkyloxymethyl Derivatives of 2ʹ-Deoxyuridine Bearing 2,4-Dinitrophenyl and Dansyl Groups: Synthesis and Antibacterial Activity

Condensation of 3ʹ,5ʹ-di-O-acetyl-5-bromomethyl-2ʹ-deoxyuridine with 6-trifluoroacetylaminohexan1-ol yielded 5-(6-trifluoroacetylaminohexyl-1-oxymethyl)-3ʹ,5ʹ-di- O-acetyl-2ʹ-deoxyuridine. Its deblocking with an aqueous alcoholic solution of ammonia gave 5-(6-aminohexyl-1-oxymethyl)-2ʹ-deoxyuridine, and condensation with triazole and 2-chlorophenyl phosphorodichloridate followed by treatment with an aqueous solution of ammonia led to the formation of 5-(6-aminohexyl-1-oxymethyl)-2ʹ-deoxycytidine. The interaction of the obtained compounds with 2,4-dinitrofluorobenzene or N-hydroxysuccinimide esters of N-2,4-dinitrophenylaminohexanoic acid or 5-dimethylaminonaphthalene-1-sulfonyl glycine was used to synthesize DNP- and DNS-derivatives of 2ʹ-deoxyuridine as well as 5-(6-DNP-aminohexanoylaminohexyl-1-oxymethyl)-2ʹ-deoxycytidine. DNP derivatives of 2ʹ-deoxyuridine were shown to inhibit the growth of Micrococcus luteus.

Adsorption of Carbon Dioxide on Shirasu‐based Materials

AbstractThis work investigated adsorption of carbon dioxide on Shirasu‐based materials with various pretreatment procedures. A Shirasu‐based material pretreated via calcination procedure followed by treatment in aqueous ammonia solution adsorbed significantly high amount of carbon dioxide compared with pristine Shirasu‐based material and the Shirasu‐based material pretreated via only solution treatment in aqueous ammonia solution. The ability improved through addition of appropriate amount of water before the adsorption process of carbon dioxide, and exhibited comparative adsorption amount of carbon dioxide with high performance materials previously reported.

Synthesis of Two-Dimensional NiO Nanostructures by a Combination of Programmable Chemical Deposition and Hydrothermal Treatment

The synthesis of two-dimensional NiO nanostructures by programmable chemical deposition in combination with the hydrothermal treatment of intermediates in distilled water and in aqueous ammonia solution was studied. Simultaneous thermal analysis was used to determine the dependence of thermal stability and sorption capacity of particles of the intermediates on the parameters of their hydrothermal treatment and on the composition of the dispersion medium. The results of IR spectroscopy and X-ray diffraction analysis helped us to recognize the crystal structure specifics and the set of functional groups for intermediates and for NiO nanopowders formed on their basis. The average size of the coherent scattering regions (CSRs) of the manufactured nickel oxide powders varied from 4.0 ± 0.5 to 8.6 ± 0.8 nm depending on the hydrothermal treatment parameters. Scanning (SEM) and transmission (TEM) electron microscopy showed that the recrystallization of NiO nanoparticles can be tuned depending on the synthesis parameters to yield two-dimensional nanostructures of various shapes and required sizes, ranging from nanosheets of chaotic geometry to flat hexagons with a variable diameter. Due to their anisotropic microstructure, the manufactured nanomaterials can be effectively used in the fabrication of functional components for advanced alternative energy devices (supercapacitor electrodes, solid oxide fuel cells, etc.), including the use of printing technologies.

Radiolysis of aerated aqueous ammonia solutions

Radiolysis of aerated aqueous ammonia solutions

Tailored synthesis of iron oxide nanoparticles for specific applications using a statistical experimental design

For this work, iron oxide nanoparticles are synthesized by the co-precipitation method with stoichiometric amounts of Fe2+ and Fe3+ salts in a 1:2 ratio in distilled water and the pH is raised by adding an aqueous ammonia solution by controlled dripping. Nanoparticles precipitating after the reaction time are magnetically filtered and stored in ethanol for further analysis. Superparamagnetic Fe3O4 nanoparticles with a slight deviation from the stoichiometry are obtained, with sizes between 7.4 and 12.8 nm and saturation magnetization between 40 and 78 emu/gr. At pH 6, rod-shaped nanoparticles are obtained in addition to spherical ones. With a statistical design, it is shown how the morphological, structural and magnetic properties of the resulting nanoparticles can be manipulated by the synthesis parameters, offering many possibilities to tailor the materials to a wide range of applications.

Controlling Metal-Oxide Reducibility for Efficient C-H Bond Activation in Hydrocarbons.

Knowing the structure of catalytically active species/phases and providing methods for their purposeful generation are two prerequisites for the design of catalysts with desired performance. Herein, we introduce a simple method for precise preparation of supported/bulk catalysts. It utilizes the ability of metal oxides to dissolve and to simultaneously precipitate during their treatment in an aqueous ammonia solution. Applying this method for a conventional VOx -Al2 O3 catalyst, the concentration of coordinatively unsaturated Al sites was tuned simply by changing the pH value of the solution. These sites affect the strength of V-O-Al bonds of isolated VOx species and thus the reducibility of the latter. This method is also applicable for controlling the reducibility of bulk catalysts as demonstrated for a CeO2 -ZrO2 -Al2 O3 system. The application potential of the developed catalysts was confirmed in the oxidative dehydrogenation of ethylbenzene to styrene with CO2 and in the non-oxidative propane dehydrogenation to propene. Our approach is extendable to the preparation of any metal oxide catalysts dissolvable in an ammonia solution.

Improving carbon dioxide capture in aqueous ammonia solutions by fine SiO 2 particles

Improving carbon dioxide capture in aqueous ammonia solutions by fine SiO 2 particles

The Reactivity-Enhancing Role of Water Clusters in Ammonia Aqueous Solutions.

Among the many prototypical acid-base systems, ammonia aqueous solutions hold a privileged place, owing to their omnipresence in various planets and their universal solvent character. Although the theoretical optimal water-ammonia molar ratio to form NH4+ and OH- ion pairs is 50:50, our ab initio molecular dynamics simulations show that the tendency of forming these ionic species is inversely (directly) proportional to the amount of ammonia (water) in ammonia aqueous solutions, up to a water-ammonia molar ratio of ∼75:25. Here we prove that the reactivity of these liquid mixtures is rooted in peculiar microscopic patterns emerging at the H-bonding scale, where the highly orchestrated motion of 5 solvating molecules modulates proton transfer events through local electric fields. This study demonstrates that the reaction of water with NH3 is catalyzed by a small cluster of water molecules, in which an H atom possesses a high local electric field, much like the effect observed in catalysis by water droplets [ PNAS 2023, 120, e2301206120].

Simulation of ammonia injection system for a compression ignition engine

Ammonia in anhydrous and aqueous forms, are attractive carbonless fuels for future marine diesel engines. The aim of this study was to determine if these fuels could be injected into a two-stroke marine diesel engine using a unit injector system. In this study, existing in service injector hardware was used to develop a dynamic numerical injector model. The results of the simulation were then validated against injector performance literature obtained for an engine, using conventional diesel fuel oil. Using the developed numerical model, the injection performance of anhydrous and aqueous ammonia solutions could then be investigated. The study found good correspondence between the model and the pressure trace found in literature. In terms of fuel injection performances, it was found that both fuels were injectable with a unit injector, however the correct volume and mass required were not achieved. Furthermore, injection timing and duration were affected marginally. For aqueous ammonia, with the higher bulk modulus, injection was advanced by 0.21 CA degrees and for anhydrous ammonia with a lower bulk modulus; it was delayed by 0.21 CA degrees. Overall proper operation of the injection system was observed. This outcome is promising, especially in shifting the maritime industry towards zero carbon ammonia engines.

Direct electrochemical detection mechanism of ammonia in aqueous solution using Cu-decorated Si microelectrodes

Most of the reports on electrochemical ammonia detection with copper electrodes have been performed at pH 10 or higher. However, according to phase diagrams, no reactions take place between copper and ammonia under those conditions, qualifying such detec­tion of ammonia as indirect. This short paper deals with the detection of ammonia concen­tration in the micromolar range through a direct mechanism at pH 9, using a Cu-decorated microstructured Si electrode. The reaction mechanism is thoroughly studied.

Effect of selected green corrosion inhibitors on SO2 removal during carbon steel corrosion in aqueous solutions of ammonia and histidine

To understand the feasibility of using carbon steel in the flue gas desulfurization process, the corrosion protection of carbon steel was investigated by adding four green corrosion inhibitors (12-aminolauric acid; 4-carboxyphenylboronic acid; 1,2,3-benzotriazole; and L-methionine) to an ammonia solution containing histidine as the SO2 absorbent. The effects of the corrosion inhibitors on the corrosion rates of carbon steel and SO2 absorption performance were investigated. We observed that 1,2,3-benzotriazole was the most effective corrosion inhibitor, reducing the corrosion rate by 73 % and increasing the SO2 absorption loading by 8.3 % compared to other corrosion inhibitors. Scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray diffraction studies were conducted to understand the corrosion inhibition behavior of 1,2,3-benzotriazole. The formation of the Fen-(SO2-BTA)m complex and its subsequent adsorption on the carbon steel surface blocked active sites and inhibited corrosion. This study demonstrated the feasibility of effectively using carbon steel under harsh environmental conditions such as in desulfurization.