Presence Of HNO3 Research Articles

Recovery of valuable metals from spent lithium-ion batteries through an ecofriendly catalytic approach

The rapid growth of lithium-ion batteries (LIBs) used in electric vehicles is amplifying the importance of recycling valuable materials from spent batteries. Current recycling technologies utilize extractive metallurgical processes to recover metals, particularly from cathode materials. However, pyrometallurgy requires high temperatures for smelting, while hydrometallurgy relies on toxic chemical reagents for leaching. Here, we present a catalytic strategy designed to overcome the energy and environmental challenges associated with metallurgical processes. The extraction reaction is conducted using an HxRuO2 catalyst in the presence of HNO3, H2, and CO2. Extraction is achieved through the selective hydrogenation of nitrate to ammonia, followed by the carbonation of leached metal species. The catalytic process successfully achieves nearly complete recovery of Co and Li as carbonates from LiCoO2. Furthermore, we demonstrate the versatility of this catalytic approach in recovering metals from various cathode materials, including spent LIBs. This newly developed one-pot method offers a promising industrial process for recycling valuable metals from spent batteries in an atom-efficient and environmentally friendly manner, without generating waste.

Reductive Treatment of δ-MnO2 with Sodium Borohydride: Method for Increasing the Electrode Material Capacitance

The effect of reductive treatment on the phase composition, morphology, and electrochemical parameters of δ-MnO2 produced by the hydrothermal method from KMnO4 at a temperature of 160°C in the presence of HNO3 was studied. δ-MnO2 processing with 3 M NaBH4 aqueous solution leads to partial reduction of Mn(IV) to Mn(III) and Mn(II). The electrochemical characteristics of the obtained electrode materials were examined by cyclic voltammetry, galvanostatic charge–discharge measurements, and impedance spectroscopy. Reductive treatment increases the specific capacitance of δ-MnO2 in 1 M Na2SO4 up to 204 F g–1 at a current density of 0.1 A g–1, and also reduces diffusion limitations during cycling due to an increase in the specific surface area. The loss of specific capacitance after 2000 charge–discharge cycles does not exceed 2.6%, which confirms the high electrochemical stability of the obtained electrode materials.

Radiolysis of diamide phenanthroline extractant: exploring the mechanism of HNO3 enhancing the extraction and An/Ln separation performance after irradiation

The stability of organic extractant molecules against radiolysis is critical in the field of actinides and lanthanides (An/Ln) separations. In order to evaluate the radiolytic effects on the extraction performance, the solutions of N,N’-diethyl-N,N’-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) in n-octanol were subjected to γ-irradiation in the presence and absence of 3 mol/L HNO3 aqueous phase. Et-Tol-DAPhen diluted in n-octanol was almost completely decomposed after irradiation and exhibits decreased extraction ability at an absorbed dose of about 384 kGy, along with the appearance of various degradation products. Et-Tol-DAPhen, which was diluted in n-octanol, was completely decomposed upon irradiation in the presence of 3 mol/L HNO3 aqueous phase. However, it exhibited higher DU and SFU/Eu values than before irradiation, as well as degradation products that were also generated. The structures of some isomers of radiolytic products were investigated by density functional theory (DFT) calculations, the radiolysis pathways and products of Et-Tol-DAPhen extractants were obtained, and the radiolysis pathways and products of Et-Tol-DAPhen extractants was proposed. The radiolytic products mainly originated from amide bond and NC bond cleavage of side group substituents, and some resulted from interaction with n-octanol radicals generated during radiolysis. The presence of HNO3 can inhibit the radiolysis of Et-Tol-DAPhen to a certain extent and cause enhanced extraction ability. Moreover, the DFT calculations reveal that the radiolytic products produced in presence of 3 mol/L HNO3 aqueous phase also have efficient extraction performance towards UO22+. The understanding of the radiolysis pathways and products of extractants, based on radiation chemical effects is expected to be helpful for developing new strategies for extractants with long-term performance.

The Barrier-Enhancing Function of Soluble Yam (Dioscorea opposita Thunb.) Polysaccharides in Rat Intestinal Epithelial Cells as Affected by the Covalent Se Conjugation

The non-starch yam polysaccharides (YP) are the bioactive substances of edible yam, while Se is an essential nutrient for the human body. Whether a covalent conjugation of Se to YP might cause bioactivity change for the resultant selenylated YP in the intestine is still insufficiently studied, including the critical intestinal barrier function. In this study, two selenylated YP products, namely, YPSe-I and YPSe-II, with corresponding Se contents of 795 and 1480 mg/kg, were obtained by the reaction of YP and Na2SeO3 in the presence of HNO3 and then assessed for their bioactivities to a cell model (i.e., rat intestinal epithelial IEC-6 cells). The results showed that YP, YPSe-I, and YPSe-II at 5–80 μg/mL dosages could promote cell growth with treatment times of 12–24 h. The three samples also could improve barrier integrity via increasing cell monolayer resistance and anti-bacterial activity against E. coli or by reducing paracellular permeability and bacterial translocation. Additionally, the three samples enhanced F-actin distribution and promoted the expression of the three tight junction proteins, namely, zonula occluden-1, occludin, and claudin-1. Meanwhile, the expression levels of ROCK and RhoA, two critical proteins in the ROCK/RhoA singling pathway, were down-regulated by these samples. Collectively, YPSe-I and, especially, YPSe-II were more potent than YP in enhancing the assessed bioactivities. It is thus concluded that this chemical selenylation of YP brought about enhanced activity in the cells to promote barrier integrity, while a higher selenylation extent of the selenylated YP induced much activity enhancement. Collectively, the results highlighted the important role of the non-metal nutrient Se in the modified polysaccharides.

Synthesis, Characterization and Antimicrobial Activity of Novel Substituted Purine Derivatives

In the present work, three new compounds were synthesized (49a, 49b, 51). Compounds were synthesized as the reaction sequences outlined in scheme1. Nitration of the theophylline was carried out as per the literature method. In this theophylline was reacted with the 65% HNO3 in presence of the acetic anhydride at the 0-5oC. Acetic anhydride was used as a dehydrating agent in the nitration reactions. Reaction was carried out at a controlled temperature because; the high temperature may cause polynitration and oxidative breakdown of aromatic ring. Product was characterized by the FTIR, 1H NMR and mass spectra. The N-alkylation of 8-nitro theophylline can be done by using 1-chloro3-iodopropane as alkylating agent and K2CO3 as base, at controlled temperature condition to prevent polymerization and get better yield. Then the reaction of 7(2-chloro ethyl) 8-nitro theophylline, substituted aryl amines and KI was carried out in microwave oven at 140W for 15 minutes to obtain 1,3-dimethyl-7-{2-[(4-aryl amino] ethyl}-8-nitro-3, 7-dihydro-1H-purine-2, 6-dione. Keywords: Purine, Theophylline, 8-nitrotheophylline, Anti-microbial activity.

Extraction of Cd(II) picrate with benzo-18-crown-6 ether into benzene under the presence of nitric acid in water phases.

Cd(II) picrate was extracted at 298K into benzene (Bz) using benzo-18-crown-6 ether (B18C6) under the presence of HNO3 in water (w) phases. Extraction constants, such as Kex, Kex±, and Kex2±, and a conditional distribution constant (KD,A) of A- = Pic- were determined, where their extraction and distribution constants were defined as [CdLA2]Bz/P, [CdLA+]Bz[A-]Bz/P, and [CdL2+]Bz([A-]Bz)2/P with P = [Cd2+][L]Bz[A-]2 at L = B18C6 and [A-]Bz/[A-], respectively. A [HNO3]t dependence of log Kex was discussed, while ionic strength dependences of log Kex± and log Kex2± were done. Here, [HNO3]t denotes a total concentration of HNO3 added to the w phases. Also, among the eight conditions of [HNO3]t, comparing Kex with an experimental distribution ratio of Cd(II) indicated that the Kex values do not function as a measure for extraction ability of L to the present systems. Moreover, the composition of Cd(II): Pic(-I) in the extracted species was shown by changing [HNO3]t.

Hydrothermally grown α-MoO3 microfibers for photocatalytic degradation of methylene blue dye

Adsorption and photodegradation efficiency of α-MoO3 microfibers towards methylene blue (MB) dye in the aqueous solution were reported. To obtain high-quality α-MoO3 microfibers, an aqueous solution of (NH4)6Mo7O24·4H2O and citric acid was hydrothermally treated (180 °C, 12 h) in the presence of HNO3. The possible growth mechanism of microfibers in the hydrothermal reaction is explained. XRD and TEM studies provide shreds of evidence that microfibers have crystallized in a pure orthorhombic phase and grown up in the direction of [001]. The structural bonding between molybdenum and oxygen constituent elements of microfibers was further confirmed by XPS, FTIR, and Raman techniques. The estimated optical band gap of α-MoO3 microfibers (Eg = 2.68 eV) lies in the visible region, making them suitable for visible light photocatalytic application. MB adsorption and degradation capacity of microfibers were performed in the dark and light, respectively. The photocatalytic properties revealed that 90 % MB dye was degraded within 120 min illumination. Moreover, the good photocatalytic recycling capability of α-MoO3 microfibers makes them a promising photocatalyst to eliminate organic pollutants from water.

An investigation of changes in structural parameters and organic functional groups of inertinite rich lignite during acid treatment processes

ABSTRACT In the recent past, researchers have paid much attention to HF, HNO3, and HCl acids for demineralization of various types of coals with the assumption that they bring negligible amount of change in the coal structure. Here we report the changes occurring in the structural parameters and the nature of organic functional groups present in an inertinite-rich lignite coal during acid demineralization processes. The investigation has been carried out by analyzing the coal using multiple analytical tools, namely, Fourier transform infrared spectroscopy (FTIR), solid-state 13C nuclear magnetic resonance (13C-NMR), and X-ray diffraction techniques (XRD). The maximum demineralization (90.82%) and surface area (252m2/g) of coal was achieved using HF/HCl/HF process. A broad peak of =N–OH functional group was observed in FTIR spectrum of HF/HNO3 process which can be associated with the interaction of coal and nitric acid. This result is also consistent with an increase in nitrogen (from 2.0% to 5.6%) and oxygen (from 12.6% to 19.3%) content of HF/HNO3-treated coal. The NMR results indicate that the coal structure contains two aromatic rings per cluster, which remains intact even after demineralization. Some increase in the amount of phenolics or phenolic ester (from 1.4% to 3.6%), oxy-methylene (from 1.96% to 2.4%), and oxymethine (1.0% to 1.5%) in the coal structure was observed by demineralization of coal using HF/HNO3 process whereas it remains constant when HF/HCl/HF process is used, indicating that the presence of HNO3 can remove organic sulfur (up to 53.96%) from the coal sample during acid treatment processes. The aromaticity (f a) of raw coal was found to be in the range of 0.71–0.75, which increases with HF/HNO3 treatment but remains constant with HF/HCl/HF treatment. The other crystallite structural parameters obtained from FTIR, 13C-NMR, and XRD were influenced to a relatively greater extent by HF/HNO3 treatment when compared with HF/HCl/HF treatment of coal. This is the first detailed analysis of the structural change in the macromolecular arrangement of coal due to demineralization, which will aid toward new techniques for utilization of Indian coal in clean coal technology.

Biotite reactivity in nitric and oxalic acid at low temperature and acid pH from surface and bulk dissolution measurements

The dissolution of biotite, a trioctahedral mica, was investigated for a temperature range of 25–70 °C and a pH range of 1–3 in the presence of HNO3 (nitric acid) and H2C2O4 (oxalic acid) solutions. Single millimetric, cleaved flakes of biotite were reacted in batch and flow-through experiments to obtain kinetic information and elucidate the mechanisms that control the overall dissolution reaction under these conditions. The reacting basal surface was explored using in-situ laser confocal microscopy (LCM-DIM) and ex-situ scanning and phase shifting interferometry (VSI-PSI), while the release of tetrahedral (Al and Si), octahedral (Mg and Fe) and exchange (K) cations in solution was monitored over time. This experimental approach allowed us to calculate far-from-equilibrium dissolution rates associated with changes in topography of the (001) surface (horizontal retreat (Rstep) and vertical retreat (Rvertical)), etch pit formation and growth (Rpit) and the release of Si in solution, i.e., bulk dissolution (Rbulk,Si). In HNO3 solutions, a proton promoted reaction mechanism (PPRM), through proton adsorption on the biotite surface, was dominant. The variation of Rstep, Rvertical and Rbulk,Si accounting for the dissolution of (hk0) surfaces at different temperature and pH was used to calculate the apparent activation energy (Ea) and the proton reaction order (nH+). The respective values decreased from 63 kJ mol−1 at pH 1 to 31 kJ mol−1 at pH 3 and increased from 0.46 at 25 °C to 0.77 at 70 °C. This variability was related to the variation of proton consumption with temperature. In H2C2O4 solutions, formation and growth of etch pits on the (001) surface occurred, yielding an increase in surface roughening. Rpit accounted for the rate of etch pit development which was observed to increase, as temperature increased. Based on Rpit, relatively high Ea values (121 kJ mol−1 and 162 kJ mol−1) were associated with an early evolution of the basal etch pits, whereas lower values (36 kJ mol−1 and 56 kJ mol−1) were calculated using Rbulk,Si. The present study contributes to the interpretation of the mechanisms involved in the biotite dissolution process at highly acidic pH, in the presence of inorganic and organic acid, and low temperature (T ≤ 80 °C). Furthermore, our results highlight the importance of combining surface and bulk analyses to assess the balance between the different reactions involving proton consumption during the dissolution and its dependency on temperature, pH and organic acids concentration.

Description of the Extraction of Trivalent REE and TPE Nitrates with Tributyl Phosphate and Its Solutions in Paraffins in the Presence of Nitric Acid and Salting-out Agents Using a Unified Model

The extraction of trivalent REE and TPE nitrates with tributyl phosphate and its solutions in paraffins at room temperature in the presence of HNO3 is described mathematically using a unified model involving parallel occurrence of several equilibrium reactions, suggested previously for modeling the extraction equilibria with REE and TPE in neutral systems and with hexavalent actinide nitrates in acid systems. The previously suggested set of equations was supplemented by the equation of the formation of a complex acid in the organic phase via addition of the HNO3 molecule to the element trisolvate.

NOx scrubbing with H2O2/HNO3 solutions achieved with a laboratory bubble contactor

In this work, the removal of dilute nitrogen oxides NOx from the gaseous effluents of Tunisian nitric acid plant by absorption into aqueous hydrogen peroxide solutions containing or not nitric acid was studied. All semi-continuous absorption tests were carried out at ambient conditions and at 40 Pa as NOx partial pressure. The effects of the gas flow rate, the initial H2O2 concentration and the presence of HNO3 on the NOx absorption efficiency (ANOx) were studied. The tests results revealed that ANOx increases with an increase in initial H2O2 concentration in the scrubbing liquid, but decreases with an increase of gas flow rate. Furthermore, the presence of nitric acid in the aqueous hydrogen peroxide solution has a positive effect on ANOx. These results confirmed that the removal of NOx liberated from the plants of the Tunisian Chemical Group (TCG) by absorption into H2O2 solution is a feasible and an effective solution.

Ambient temperature ZrO2-doped TiO2 crystalline photocatalysts: Highly efficient powders and films for water depollution

In this paper, several TiO2 materials doped with zirconia precursor (0.7, 1.4, 1.6 and 2.0 mol%) were synthesized by an easy aqueous sol-gel synthesis at ambient temperature. This method consists in the peptization of the TiO2 colloid in presence of HNO3. The corresponding pure TiO2 material was also synthesized for comparison. The performances and the physico-chemical properties of these materials were compared to the well-known Evonik P25 photocatalyst.The physico-chemical characterizations showed that nano-crystalline anatase-brookite particles were produced with the sol-gel process, with higher specific surface area than P25 (∼200 m2 g-1 vs. 47 m2 g-1). All samples presented a higher visible absorption than P25. The XPS spectra showed that all the samples were doped with nitrogen and that mixed TiO2–ZrO2 oxide materials were obtained when doping with zirconia precursor.Photoactivity was evaluated through the degradation of p-nitrophenol in water. On the one hand, under UV/visible light, the ZrO2 doping increased the degradation efficiency of the pure TiO2 catalyst due to a better charge separation in the mixed TiO2–ZrO2 oxides. The activity of the sample with the highest dopant content was even higher than the one of P25. On the other hand, under visible light, all samples were much more efficient than P25. This activity shift towards visible range was due to the N-doping of the catalysts, with a slight improvement for the doped ones.Finally, the feasibility of producing films starting from an aqueous suspension of the photocatalyst was assessed on P25, pure TiO2 and the best doped material. The photoactivity of these films, evaluated on the degradation of methylene blue under UV-A light, showed that the sample with the highest dopant concentration had an efficiency 4 times higher than pure TiO2 and 20 times higher than P25.

High-Performance Supercapacitor Electrode of HNO3 Doped Polyaniline/Reduced Graphene Oxide Nanocomposites

Polyaniline (PANI) nanorods were prepared by a chemical method in the presence of HNO3 as an acid dopant. Reduced graphene oxide (RGO) sheets were synthesized and used as a substrate for the polymerization of PANI, affording the PANI–RGO nanocomposites. The PANI composites with RGO were synthesized in the presence of dopant (dPANI–RGO) and without dopant (PANI–RGO). A comparative study was performed for RGO, PANI, dPANI, PANI–RGO and dPANI–RGO. The nanocomposites were characterized by XRD, FESEM, FTIR and TGA. XRD study showed that the dPANI–RGO is more crystalline in nature. The FESEM studies revealed that longer polyaniline nanotubes can be obtained on RGO sheets in the presence of RGO with HNO3. FTIR results show a greater extent of formation of quinoid units in the presence of both HNO3 and RGO, while benzenoid units show this effect only with HNO3. TGA results showed successful incorporation of RGO sheets with the enhanced thermal stability of dPANI–RGO as compared to dPANI. The electrochemical behavior of dPANI–RGO was also investigated. In the presence of RGO and HNO3, longer polyaniline nanotubes grow on RGO sheets forming a continuous network for electron transfer resulting in low charge transfer resistance for dPANI–RGO (3 Ω) as compared to PANI (29 Ω), which ultimately improves the electrochemical performance of the nanocomposites as a supercapacitor electrode material. The dPANI–RGO nanorods exhibited a specific capacitance of 563 F/g and good cycling stability up to the 5000 cycles with 84% specific retention at 0.5 A g−1.

Structural Modification of Starch Nanoparticles Via Graft Copolymerization Using KMnO4, HClO4 and HNO3 Redox Pair

The novelty addressed here is commenced with a view to use our formerly prepared starch nanoparticles (SNPs) of size around 80–100 nm as a starting substrate for grafting meth acrylic acid (MAA) using KMnO4, HClO4 in presence of HNO3 as innovative redox pair in aqueous medium. This was done to see the effect of SNPs with respect to well-dispersed nanosized particles, large surface areas, biodegradability and reactivity on the rate and extent of grafting. Besides; maximize the graft yield and graft reaction efficiency and reduce the homopolymer formation to lower extent. This could be accomplished via an in-depth assessment into the chief factors affecting the polymerization reaction such as initiator, monomer, SNPs and acid concentrations, time and temperature of polymerization, and liquor ratio. The results obtained indicate that the magnitude of the polymer yield including graft yield, graft reaction efficiency and homopolymer formation are determined by these factors. The structure of the resultant copolymers was confirmed instrumentally by Fourier transforms infrared spectroscopy; while both the surface morphology, crystalline structure and thermal properties were characterized by scanning electron microscopy, X-ray diffraction and thermal gravimetric analysis. Furthermore, the resultant copolymers were evaluated as environmental remediation materials via cadmium ions and cationic dyes removal from their solutions with different extent; in addition to higher swelling and chemical resistance in water as polar solvent and hydrochloric acid as acidic solution. The anticipated mechanisms involved in the synthesis are reported.

Syntheses, Structures, and Catalytic Hydrocarbon Oxidation Properties of N-Heterocycle-Sulfonated Schiff Base Copper(II) Complexes

Reaction of the o-[(o-hydroxyphenyl)methylideneamino]benzenesulfonic acid (H2L) (1) with CuCl2·2H2O in the presence of pyridine (py) leads to [Cu(L)(py)(EtOH)] (2) which, upon further reaction with 2,2’-bipyridine (bipy), pyrazine (pyr), or piperazine (pip), forms [Cu(L)(bipy)]·MeOH (3), [Cu2(L)2(μ-pyr)(MeOH)2] (4), or [Cu2(L)2(μ-pip)(MeOH)2] (5), respectively. The Schiff base (1) and the metal complexes (2–5) are stabilized by a number of non-covalent interactions to form interesting H-bonded multidimensional polymeric networks (except 3), such as zigzag 1D chain (in 1), linear 1D chain (in 2), hacksaw double chain 1D (in 4) and 2D motifs (in 5). These copper(II) complexes (2–5) catalyze the peroxidative oxidation of cyclic hydrocarbons (cyclooctane, cyclohexane, and cyclohexene) to the corresponding products (alcohol and ketone from alkane; alcohols, ketone, and epoxide from alkene), under mild conditions. For the oxidation of cyclooctane with hydrogen peroxide as oxidant, used as a model reaction, the best yields were generally achieved for complex 3 in the absence of any promoter (20%) or in the presence of py or HNO3 (26% or 30%, respectively), whereas 2 displayed the highest catalytic activity in the presence of HNO3 (35%). While the catalytic reactions were significantly faster with py, the best product yields were achieved with the acidic additive.

Reduction of Aqueous Ag+ Steered by Electrochemical Plasma: Connecting the Bulk pH Variation with the Reaction Pathways for Hydrated Electrons

Reduction of silver cations followed by nanoparticle (Ag-NPs) synthesis is a model process to understand the reduction mechanism induced by a discharge over an aqueous surface, termed electrochemical plasma. This work aims at studying the silver reduction reaction steered by electrochemical plasma in the presence of other chemically active plasma-related interfaces, namely the plasma-gas and the liquid-gas interfaces. As no other plasma-induced species are able to reduce silver cations, the reduction of silver cations is employed as strategy to selectively detect the presence of hydrated electrons (e-h). The results demonstrate that the global rise of pH (increase in the content of OH-), observed for discharge in the helium gas phase, occurs in connection with the silver reduction, which is interpreted as a vivid experimental evidence of the second-order recombination reaction of theeh−2eaq−+2H2O→H2+2OH−. On the other hand, the global decrease of pH (increase in the content of H+) observed for discharge in mixed oxygen and nitrogen gas phase, is an event primarily driven by the Birkeland-Eyde process, and it is concomitant but spatially distinct from the electron injection. The acidification interferes in the NP formation, as NPs promptly dissolve in presence of HNO3. Only in complete suppression of the acidification, an experimental evidence of the reaction pathways for hydrated electron could be captured: e-h is competitively consumed through a scavenger-like reaction (reduction of silver cations in this work) and through the second-order recombination reactions of the e-h. The kinetic model proposed in this work further corroborates this interpretation.

Reductive dissolution studies of CeO2 and simulated mixed oxide fuel of (Ce, U)O2 in nitric acid medium

In dissolution studies involving plutonium oxide, oxides of cerium are employed as a non radioactive surrogate. A reductive dissolution of cerium oxide and mixed oxide consisting cerium-uranium were investigated in nitric acid medium in presence of uranous. Extensive dissolution studies were carried out using ceria powder in pure HNO3 and HNO3–[N2H5]+ [NO3]− with U(IV). The effects of temperature, mixing rate and concentration of reducing agent on dissolution efficiency of CeO2 were investigated. The apparent activation energy was calculated from Arrhenius plot for dissolution of cerium oxide in HNO3 in presence of uranous stabilized by hydrazine and it was found to be about 40 kJ mol−1 in the temperature range of 300–350 K. The fraction of total mass of uranium and cerium from the mixed oxide pellet leached as function of time was monitored during dissolution performed under optimized conditions and dissolution yield was found to be > 99%.

Extraction Behavior of Ln(III) Ions by T2EHDGA/n-Dodecane from Nitric Acid and Sodium Nitrate Solutions

ABSTRACTThe diglycolamide extractant T2EHDGA has proven to be promising for the separation of lanthanides and minor actinides in high-level nuclear waste reprocessing. This neutral extractant has shown significant extraction capacity for HNO3 into the nonpolar organic phase, along with hyper-stoichiometric nitrate dependence on extraction of trivalent f-elements. The transport behavior of T2EHDGA/n-dodecane toward trivalent lanthanides is not well understood. This work found a significant increase in distribution ratios for Eu(III) extracted from aqueous HNO3 media compared with that from NaNO3. The extraction of Eu(III) from HNO3 results in a different thermodynamic product than predicted by classic solvent extraction of 3:1 ligand–metal complex as observed with NaNO3 in FTIR and UV-vis spectroscopy. Experimental distribution measurements in conjunction with mass-action modeling using the solvent extraction modeling program SXLSQI suggest participation of 1 to 2 HNO3 molecules in the Eu(III)/T2EHDGA complex upon extraction from HNO3 media, indicative of a mechanism change responsible for the enhanced extraction behavior toward lanthanides in the presence of HNO3.

Light Metal Li/K-Based Energetic Coordination Polymers: Structural Effect on Detonation Performance

It is the current development trend to contribute green high-energy coordination polymers (CPs) with light metal to realize effective energy density. In this study, self-assembly of a ligand 3-(tetrazol-5-yl)triazole (H2tztr) with the light metal Li produces Li–CP [Li2(Htztr)2(H2O)4] (1a). Further structure recombination generates the polymorph (1b) in the presence of HNO3, which displays better detonation performance. Nevertheless, the detonation performance is affected by multiple water molecules, which may take some energy away because they evaporate at lower temperatures. Hence, we selected K(I) with the larger radius to replace Li(I), expecting that more ligands participate in coordination, which not only increases energetic units but also avoids a large amount of coordinated H2O molecules. Compound [K(Htztr)(H2O)]n (2) with a two-dimensional structure was prepared by facile synthesis, which effectively reduces coordinated H2O molecules. Particularly, 2 possesses outstanding detonation performance wi...

Nitric Acid and Water Extraction by T2EHDGA in n-Dodecane

ABSTRACTLiquid–liquid distribution behavior of nitric acid (HNO3) and water by a diglycolamide (DGA) ligand, N,N,N’,N’-tetra-2-ethylhexyldiglycolamide (T2EHDGA), into n-dodecane diluent was investigated. Spectroscopic Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) characterization of the organic extraction solutions indicate the T2EHDGA carbonyl coordinates with HNO3 and progressively aggregates at high acid conditions. Water extraction increases in the presence of HNO3. The experimentally observed distribution of HNO3 was modeled using the computer program SXLSQI. The results indicated that the formation of two organic-phase species—HNO3·T2EHDGA and (HNO3)2·T2EHDGA—satisfactorily describes the acid distribution behavior. Temperature-dependent solvent extraction studies allowed for the determination of thermodynamic extraction constants and ΔH and ΔS parameters for the corresponding extractive processes.