Hydrazine In Aqueous Solution Research Articles

Hydrazine Oxidation in Aqueous Solutions II: N4H4 Decomposition

AbstractThe reaction mechanism for the N2H4 homogeneous oxidation in aqueous solutions is more complex than its heterogeneous electrochemical oxidation on the electrode surfaces. Homogenous oxidation of a mixture of non‐labeled (14N2H4) and 15N‐labeled (15N2H4) hydrazine in aqueous solutions produces 14N15N, indicating the intermediate existence of N4H6 or N4H4 intermediates with subsequent hydrogen transfers and splitting lateral N─N bonds. To explain the key part of the hydrazine oxidation reaction, the structures, thermodynamics, and electron characteristics of N4H4 in aqueous solution are investigated. Unlike N4H6, we have not found any spontaneous splitting of the bond between the lateral nitrogens in N4H4. The most probable products of N4H4 disproportionation are H2N─NH2 and N2, which are obtained by splitting the bond between the central nitrogen atoms, and so only 15N2 and 14N2 molecules are formed. Additionally, the formation of H3N─NH and N2 products is also preferred to structures without N─N fissions. The formation of H2N═N and HN═NH is energetically less advantageous. Cyclo‐N4H4 structures are stable, without any N─N fissions, but their energies indicate their vanishing abundance in aqueous solution, so their involvement in hydrazine oxidation is highly improbable. Unlike N4H6, the oxidation of hydrazine to 14N15N molecules cannot be explained by N4H4 intermediates.

Phenothiazine-based fluorescent probes for the detection of hydrazine in environment and living cells

As an important chemical raw material, hydrazine brings convenience to people's lives and provides opportunities for human development. However, the misuse or leakage of hydrazine has brought pollution to the environment, including water, soil and living organisms. At the same time, hydrazine poses a potential threat to human health as a carcinogen. Despite the enormous challenges, it is crucial to develop an effective method to detect hydrazine in environmental samples. In this work, we have synthesized a series of probes based on phenothiazine fluorophore by the introduction of different substituents and developed a novel probe for the detection of hydrazine. The probe is capable of detecting hydrazine in aqueous solutions with high sensitivity and selectivity, and can be easily fabricated into paper test strips for use in in situ samples. In addition, the probe is effective in detecting hydrazine in water, soil, cells, and zebrafish, providing an excellent tool for detecting hydrazine in the environment.

Selective Thermal and Photocatalytic Decomposition of Aqueous Hydrazine to Produce H2 over Ag-Modified TiO2 Nanomaterial.

An Ag-modified TiO2 nanomaterial was prepared by a one-pot synthesis method using tetra butyl titanate, silver nitrate, and sodium hydroxide in water at 473 K for 3 h. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to determine the structure and morphology of the synthesized Ag-modified TiO2 nanomaterial. The diffuse reflectance UV-visible and photoluminescence spectroscopy results revealed that metallic Ag nanoparticles decreased the optical band gap and photoluminescence intensity of the TiO2. In addition, the Raman peak intensity and absorbance were increased after Ag modification onto TiO2. The photocatalytic efficiency of the synthesized samples was tested for decomposition of aqueous hydrazine solution under visible light irradiation. The photocatalytic efficiency of Ag-modified TiO2 nanomaterials was higher than that of bare TiO2 and Ag metal NPs due to the synergistic effect between the Ag metal and TiO2 structures. In addition, the surface plasmon resonance (SPR) electron transfer from Ag metal particles to the conduction band of TiO2 is responsible for superior activity of TiO2-Ag catalyst. The Ag-modified TiO2 nanomaterials offered a 100% H2 selectivity within 30 min of reaction time and an apparent rate constant of 0.018 min-1 with an activation energy of 34.4 kJ/mol under visible light radiation.

Synthesis, characterization, and hydrazine sensing property of two covalent organic frameworks

AbstractSensitive and efficient detection of hydrazine is of great significance because hydrazine is a highly toxic organic molecule, which can pose great threats to human health. Herein, two covalent organic frameworks (COFs) modified with ester groups in the pores, TAPB‐DHE and TAPT‐DHE, have been successfully synthesized via esterification reaction. Both of the two COFs have good crystallinity, thermal stability, and fluorescence properties. TAPB‐DHE can be used as a turn‐on fluorescence sensor for the sensitive detection of trace hydrazine in aqueous solution with a detection limit of 0.40 μM and a wide linear range of 0–100 μM due to the fluorescence enhancement of TAPB‐DHE caused by the chemical reaction between hydrazine and TAPB‐DHE, in which the ester group of the COF is converted into hydroxyl group, leading to the restriction of the intramolecular charge transfer (ICT) effect. This work provides a reference for the design of COFs with hydrazine recognition function and a helpful expansion for the practical application of COFs.

Naphthalene-based fluorescent probe for on-site detection of hydrazine in the environment.

The widespread occurrence of hydrazine residues in the environment, including in water, soil, and organisms, is a potential health threat to humans. Therefore, the development of an efficient method for the detection of hydrazine in environmental samples is highly desirable although it poses a significant challenge. In this study, we designed and synthesized a series of naphthalene-based fluorescent dyes through structural engineering and developed a novel probe for hydrazine detection. The probe could provide a distinct fluorescence response toward hydrazine in aqueous solution with high sensitivity and selectivity. Moreover, paper-based test strips can be easily fabricated using this probe, enabling the portable on-site detection of hydrazine with the aid of a smartphone. Furthermore, we demonstrated that this probe is capable of recognizing hydrazine in various environmental samples, including water, soil, plants, and zebrafish embryos. This research provides a promising tool for the detection of hydrazine in the environment.

Structural and spectroscopic characterization of the products formed in aqueous solution of hydrazine and maleic acid

• Structural and Spectroscopic studies were carried out using XRD and Spectroscopic techniques. • NBO and HOMO-LUMO energies were estimated. • DFT calculations were accomplished by using B3LYP with 6-311++G(d,p) basis set. • The intermolecular interaction has been evaluated by Hirshfeld surface analysis. The detailed investigation of the structural and spectroscopic characterization of the products formed in aqueous solution of hydrazine and maleic acid is studied in the current research. Single crystal X-ray diffraction inquiry concedes that obtained crystal hydrazinium fumarate ( 1 ) crystallises in the centrosymmetric space group P2 1 /c of the monoclinic system with four molecules per unit cell, whereas maleic hydrazide in the monolactim form ( 2 ) crystallises in the triclinic system with centrosymmetric space group and possess two molecules per unit cell. Further the structure of hydrazinium fumarate is optimized by using density functional theory with B3LYP/6-311++G(d,p) level. Structural and vibrational spectral analysis has been established by both experimental and theoretical method. B3LYP exchange correlational hybrid with 6-311++G (d, p) basis sets are used to assign all modes of vibration and analyse the structure of the molecule in terms of parameters like bond length, bond angle, and dihedral angle. The charge transfer between localised bonds and lone pairs is visualised via NBO analysis. The HOMO–LUMO mappings are presented, revealing the molecule's many charge transfer possibilities. The non-linear attribute of the molecule is described using the dipole moment (μ), polarizability (α), and hyperpolarizability (β) values of the molecule. The Crystal Explorer Ver. 3.1 tool is used to calculate Hirshfeld surface analyses, 2D fingerprint plots, and percentage contributions for several intermolecular interactions in the examined crystal hydrazinium fumarate (1).

Ratiometric fluorescence chemodosimeter for hydrazine in aqueous solution and gas phase based on Quinoline-Malononitrile

The widespread use of Hydrazine (N2H4) in many areas of the chemical industry, brings potential risks to human health and environmental pollution. To detect N2H4 effectively, a simple ratio fluorescence probe (QMM), designed and synthesized through Vilsmeier reaction and Knoevenagel reaction, was prepared for the specific response of N2H4 based on the irreversible chemical reaction. The ratiometric fluorescence chemodosimeter displayed a response for hydrazine with high selectivity, sensitivity and anti-interference ability. The measured detection limit is 38.30 nm (0.122 ppb), which is far lower than the maximum allowable level of the U.S. Environmental Protection Agency (10 ppb). Moreover, test paper and TLC plates loading QMM had been made, which could be utilized to detect hydrazine both in aqueous solution samples and in gas phase samples. Thus QMM could serve as an easily manufactured, low-cost, efficient and portable solid-state optical probe to detect hydrazine in field measurements.

Zeolitic imidazolate framework derived porous ZnO/Co3O4 incorporated with gold nanoparticles as ternary nanohybrid for determination of hydrazine

A sensing platform based on porous ZnO/Co3O4 is introduced for determination of hydrazine in alkaline media. The bimetallic oxides were prepared by calcination of bimetallic zeolitic imidazolate framework (Zn/CoZIF) as a sacrificial template. Zn/CoZIF and ZnO/Co3O4 were characterized via several techniques. The porous ZnO/Co3O4 was utilized to modify glassy carbon electrode (ZnO/Co3O4/GCE), followed by immobilization of Au nanoparticles (NPs) on its surface to prepare Au/ZnO/Co3O4/GCE. The electrode exhibited two linear ranges of 2–1900 μM and 1900–8500 μM with sensitivity of 0.058 and 0.048 μA μM−1 for determination of hydrazine in aqueous solution. The sensor showed remarkable lower oxidation potential and limit of detection rather than ZnO/Co3O4/GCE. Furthermore, the sensor displayed acceptable selectivity toward oxidation of hydrazine in the presence of some interfering species. The results confirm that Au/ZnO/Co3O4/GCE can be considered as sensitive and reliable sensor toward the oxidation of hydrazine due to the porous structure of ZnO/Co3O4, high conductivity of Au NPs, and the synergic effect among the constituents.

Coumarin 1,4-enedione for selective detection of hydrazine in aqueous solution and fluorescence imaging in living cells.

Hydrazine is a widely used but highly toxic chemical reagent, and the development of a fluorescent probe for hydrazine detection is very meaningful. In this study, a novel coumarin-derived fluorescent probe containing a 1,4-enedione moiety for hydrazine detection was developed. The recognition of hydrazine with the probe brings about obvious fluorescence enhancement over other environmentally relevant ions and amine-containing species. The limit of detection for hydrazine is 2.7×10-8 M in aqueous solution. The fluorescence enhancement was ascribed to the cyclization reaction of the 1,4-enedione moiety of the probe and hydrazine which form a six-membered pyridazine ring and intramolecular charge transfer (ICT) mechanism. The mass spectrometry (MS), nuclear magnetic resonance (NMR) analysis and theoretical calculations confirmed the recognition produced. The probe can be used to determine trace hydrazine in real water samples. More importantly, the probe also showed good potential in detecting hydrazine by imaging of living HeLa cells.

Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process-TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies.

Reduced graphene oxide (rGO) was prepared by chemical reduction of graphene oxide (GO) (with a modified Hummers method) in aqueous solutions of hydrazine (N2H4), formaldehyde (CH2O), formic acid (HCO2H) accompanied by a microwave treatment at 250 °C (MWT) by a high pressure microwave reactor (HPMWR) at 55 bar. The substrates and received products were investigated by TEM, XRD, Raman and IR spectroscopies, XPS, XAES and REELS. MWT assisted reduction using different agents resulted in rGOs of a large number of vacancy defects, smaller than at GO surface C sp3 defects, oxygen groups and interstitial water, interlayer distance and diameter of stacking nanostructures (flakes). The average number of flake layers obtained from XRD and REELS was consistent, being the smallest for CH2O and then increasing for HCO2H and N2H4. The number of layers in rGOs increases with decreasing content of vacancy, C sp3 defects, oxygen groups, water and flake diameter. MWT conditions facilitate formation of vacancies and additional hydroxyl, carbonyl and carboxyl groups at these vacancies, provide no remarkable modification of flake diameter, what results in more competitive penetration of reducing agent between the interstitial sites than via vacancies. MWT reduction of GO using a weak reducing agent (CH2O) provided rGO of 8 layers thickness.

Colorimetric recognition of hydrazine in aqueous solution by a bromophenol blue-tethered ion-pair-like ratiometric probe

Hydrazine or hydrazine hydrate (N2H4·H2O) is a potential neurotoxin and has several mutagenic effects in physiological systems. Therefore, the development of synthetic organic probes that are sensitive and selective to hydrazine is of tremendous importance. Unfortunately, however, the hydrazine-selective sensing probes that rely upon minimum usage of the organic solvents (≤5%, v/v) are still rarer. In this work, an ion-pair-like mono acetate derivative of bromophenol blue has been developed as a fairly selective ratiometric probe for the naked-eye recognition of hydrazine in a solution of tris buffer and EtOH (19:1, v/v) at physiological pH. The chromogenic signalling relies upon hydrazine-induced cleavage of an ester moiety of the probe to its resonance stabilized quinonoid form, resulting in momentous variations in its spectrophotometric profile. Meanwhile, the colour of the probe solution changed from mustard yellow to blue within few minutes. This sensing assay could be successfully applied in the recognition of hydrazine in real environmental and pharmaceutical samples with satisfactory recoveries. Given the cost-effectiveness, simplicity and versatility, for instance, direct analysis of colorimetric probes, it is reasonable to propose that the present method can serve as a complementary method for prompt inspection of hydrazine in boiler feed water.

A 7-diethylaminocoumarin-based chemosensor with barbituric acid for hypochlorite and hydrazine

A chemosensor was synthesized conveniently by the condensation between 7-diethylaminocoumarin and barbituric acid, which was used successfully for the detection of hypochlorite and hydrazine with excellent performances. This chemosensor underwent remarkable color change and turn off fluorescence in solution, while revealed turn on fluorescence on the filter paper in the presence of hypochlorite. In addition, it exhibited obvious fluorescence enhancement in solution, while no fluorescence change on the test paper after addition of N2H4. As a result, this chemosensor could be a potential candidate for hypochlorite and hydrazine in different media through two distinct response modes. It could realize the detection of hypochlorite in water with a low detection concentration of 2 μM by test strip, and trace hydrazine in aqueous solution and living HepG2 cells by the mean of fluorescence signal. Moreover, the sensing mechanisms of this chemosensor towards hypochlorite and hydrazine were suggested by HRMS and 1H NMR spectra, in which the coumarin structure was destroyed by hypochlorite and the barbituric acid was removed by hydrazine, respectively.

Amperometric assay of hydrazine utilizing electro-deposited cobalt hexacyanoferrate nanocrystals on graphene oxide sheets

In-situ electrochemical deposition of cobalt hexacyanoferrate (CoHCF) on graphene oxide (GO) and its application for the electrocatalytic hydrazine determination in real samples are described in this research study. Co2+ is immobilized on GO and the resulting material, GO-Co2+ is coated on the surface of glassy carbon (GC) electrode. The fabricated electrode (GC/GO-Co2+) is subjected to a continuous potential cycling in the range of 0.0–1.0 V which results in the formation of a thin CoHCF film on the surface of GO coated on the GC electrode (abbreviated as GC/GO-CoHCF). The synthesized GO-CoHCF composite material is characterized by Fourier transform infrared and scanning electron microscopy. GC/GO-CoHCF electrode electrocatalytically oxidizes hydrazine at low overpotential (0.63 V) and this phenomenon is subsequently utilized for the sensitive determination of hydrazine in aqueous solutions. It exhibits a wide linear calibration range (0.1–400 µM), high sensitivity (0.93 µA µM−1 cm−2) and low limit of detection (17.5 nM) for the determination of hydrazine. Further, this electrode is employed for hydrazine determination in real samples.

Hydrazine-Enabled One-Step Synthesis of Metal Nanoparticle-Functionalized Gradient Porous Poly(ionic liquid) Membranes.

In this communication, a one-step synthetic route is reported toward free-standing metal-nanoparticle-functionalized gradient porous polyelectrolyte membranes (PPMs). The membranes are produced by soaking a glass-plate-supported blend film that consists of a hydrophobic poly(ionic liquid) (PIL), poly(acrylic acid), and a metal salt, into an aqueous hydrazine solution. Upon diffusion of water and hydrazine molecules into the blend film, a phase separation process of the hydrophobic PIL and an ionic crosslinking reaction via interpolyelectrolyte complexation occur side by side to form the PPM. Simultaneously, due to the reductive nature of hydrazine, the metal salt inside the polymer blend film is reduced in situ by hydrazine into metal nanoparticles that anchor onto the PPM. The as-obtained hybrid porous membrane is proven functional in the catalytic reduction of p-nitrophenol. This one-step method to grow metal nanoparticles and gradient porous membranes can simplify future fabrication processes of multifunctional PPMs.

Monodispersed bimetallic nanoparticles anchored on TiO2-decorated titanium carbide MXene for efficient hydrogen production from hydrazine in aqueous solution

Selective catalytic decomposition of hydrazine (N2H4) to provide a clean energy carrier hydrogen (H2) is a promising alternative to fossil fuels for the future energy economy. NiPt nanoparticles (NPs) dispersed on delamination of TiO2-decorated Ti3C2Tx (denoted as DT-Ti3C2Tx) nanosheets are prepared via a simple wet chemical reduction method and applied as an efficient catalyst for dehydrogenation of N2H4 in aqueous solution. The rich oxygen-containing functional groups on the surface of DT-Ti3C2Tx not only facilitate the formation and immobilization of monodisperse NiPt NPs but also enhance the synergistic effect between metal NPs and MXene support. Among all of the tested samples, the optimized Ni0.8Pt0.2/DT-Ti3C2Tx nanocatalyst exhibits the 100% H2 selectivity and best catalytic performance with a TOF value of 1220 h−1 for the selective decomposition of N2H4 at 323 K. In addition, this catalyst also shows excellent catalytic performance for hydrogen production from hydrazine borane (N2H4BH3) via the hydrolysis of borane group and selective decomposition of hydrazine moiety. The TiO2-decorated Ti3C2Tx MXene can be applied as an excellent support to obtain well-dispersed and ultrafine metal NPs for various applications.

Noble Metal‐free Bimetallic Cobalt/Manganese Oxide Catalyst for Hydrogen Generation by Decomposition of Hydrous Hydrazine

Bimetallic cobalt and manganese oxide (Co/MnO) is prepared by annealing the spinel structure of CoMn2O4 under hydrogen environment. This noble metal‐free catalyst is applied for hydrogen generation from aqueous hydrazine solution. X‐ray powder diffraction, transmission electron microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy results indicated that the phase separation of metallic cobalt and manganese monoxide from CoMn2O4 occurs during annealing process. Co/MnO exhibits catalytic activity with the TOF value of 14.2 h−1 and 100% selectivity without generation of ammonia at 343 K. It is found that metallic cobalt plays role on the active site for hydrogen generation.

Cr2O3-modified NiFe nanoparticles as a noble-metal-free catalyst for complete dehydrogenation of hydrazine in aqueous solution

The development of highly active, stable, and inexpensive catalysts for efficient and complete dehydrogenation of hydrazine is highly attractive but still very challenging. Herein, Cr2O3-modified NiFe (NiFe-Cr2O3) nanopartciles (NPs) have been designed as the heterogeneous catalyst. Both the catalytic activity and hydrogen selectivity of Ni0.9Fe0.1-Cr2O3 NPs were improved remarkably as compared with those of their mono-metallic counterparts. The prepared Ni0.9Fe0.1-Cr2O3 catalyst exhibited an outstanding catalytic activity to release 3.0 equiv. (H2 + N2) from hydrazine in only 8.5 min at 70 °C, providing a turnover frequency (TOF) value of 893.5 h−1 based on surface metal atoms. Systematic studies indicated that the small size and high surface area of Ni0.9Fe0.1-Cr2O3 as well as the strong synergistic electronic effect between Cr2O3 and NiFe NPs resulted in the excellent activity of Ni0.9Fe0.1-Cr2O3 catalyst. Such a highly rapid, long term durability, and low cost catalyst may encourage greatly the practical application of hydrous hydrazine as a chemical hydrogen storage material.

Preparation and application of a highly sensitive conjugated polymer-copper (Ⅱ) composite fluorescent sensor for detecting hydrazine in aqueous solution

At first, a conjugated polymer (poly(2,5-bis(4-(bis(pyridin-2-ylmethyl)amino) butoxyl)-1,4-Phenylethynylene-1,4-poly(phenylene ethynylene), PPE-DPA) was synthesized based on our earlier report. In this work, a highly selective and sensitive composite fluorescent sensor (PPE-DPA-Cu2+), which was PPE-DPA complexed with copper ions, has been developed and used to measure trace amounts of hydrazine in environmental water samples. The experiment conditions were investigated. Under optimized conditions, the sensor shows satisfactory detection performance, which can highly sensitively detect hydrazine with a linear range of 0–70 nmol L−1 and detection limit as low as 5.4 × 10−10 mol L−1 (S/N = 3). Meanwhile, the sensor exhibits high selectivity and strong anti-interference ability for various cations, anions, common reducing agents and organic amines. This sensor has been applied to detect hydrazine in the real water samples, and the recovery of hydrazine was 92.3%–112.0% after added standard solution of hydrazine. Satisfactory results indicate that the sensor is expected to be utilized for quantitative detection of hydrazine in environmental samples.

Preparation of high-concentration colloid solutions of metallic copper particles and their use in metal–metal bonding processes

A high-concentration colloid solution of metallic copper nanoparticles was prepared by the reduction of copper ions in aqueous solutions, and the nanoparticles were used to study metal–metal bonding. The colloid solution of metallic copper nanoparticles was prepared by mixing an aqueous solution of CuCl2 and an aqueous solution of hydrazine (reductant) in the presence of citric acid and n-hexadecyltrimethylammonium bromide (stabilizers) at a final copper concentration as high as 0.1 M. The copper-particle size was ca. submicrometer. Many tiny particles with sizes of ca. 10–20 nm were deposited on the submicron-sized particles at high hydrazine concentrations. The tiny particles were considered to be produced through the growth of particle nuclei generated at the final reaction stage by residual hydrazine derived from the high hydrazine concentration. Metallic-copper discs were successfully bonded by annealing at 400 °C and a pressure of 1.2 MPa for 5 min in hydrogen gas with the help of the metallic-copper particles. The shear strength of the bonded copper discs was then measured. The highest shear strength of 41.7 MPa was recorded for the tiny particles/immobilized particles, which could be explained by the low melting points of the tiny particles and the increase in bulk density provided by the dominant incorporation of the tiny particles into voids between the submicron-sized particles.

Analysis of hazards occurring during the use of hydrazine

The article presents the safety issue bonded to the Polish Air Force F-16 multirole aircraft. The authors pointed out the issue of fuel used for emergency supply system of these aircrafts. The paper emphasized the fact that these aircrafts require special fuel with designation H-70, which is 70% aqueous solution of toxic hydrazine. For this reason, the rescue services of Polish Air Force bases where Polish F-16 are stationed had to be adjusted accordingly. Just as importantly authors noticed that in the event of an emergency landing of this aircraft at different airports can receive difficulties associated with the possible leakage of hydrazine, or its neutralization in the absence of specialized Hydrazine Response Team, which are part of the Airport Rescue Group.