Decomposition Of Chloride Research Articles

Oxalyl chloride as a practical carbon monoxide source for carbonylation reactions.

A method for generation of high-quality carbon monoxide by decomposition of oxalyl chloride in an aqueous hydroxide solution is described. The usefulness of the method is demonstrated in the synthesis of heterocycles and for hydroxy-, alkoxy-, amino-, and reductive carbonylation reactions, in several cases under milder conditions than previously reported.

Stoichiometric C6-oxidation of hyaluronic acid by oxoammonium salt TEMPO+Cl− in an aqueous alkaline medium

This paper reports the selective oxidation of hyaluronic acid (HA) by stoichiometric quantity of 2,2,6,6-tetramethylpiperidine-1-oxoammonium chloride (TEMPO+) in aqueous alkaline medium. High efficiency of the HA oxidation and quantitative yield of carboxy-HA per starting TEMPO+, as well as unusual behavior of the oxidation system generating an oxygen upon alkali-induced oxoammonium chloride decomposition are demonstrated. The scheme for HA oxidation involving both TEMPO+ and oxygen produced upon the TEMPO+Cl− decomposition and/or air oxygen is proposed. For comparison, the data on stoichiometric oxidation of such substrates as dermatan sulfate, water-soluble potato starch, methyl 2-acetamido-2-deoxy-β-d-glucopyranoside and ethanol are presented.

Effect of TiO2 Loading on Pt-Ru Catalysts During Alcohol Electrooxidation

In this study, Pt-Ru based electrodes modified by TiO2 were prepared by means of thermal decomposition of chloride and isopropoxide precursors on Ti substrates, characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), electrochemical techniques and CO stripping and used as anodes for alcohol oxidation. The minimization of the metal loading without electrocatalytic activity losses was also explored. TiO2 was chosen due to its chemical stability, low cost and excellent properties as substrate for metal dispersion. It was found that TiO2 loading up to 50% results in a 3-fold increase of the Electrochemically Active Surface (EAS). This conclusion has been confirmed by CO stripping experiments. All samples have been evaluated during the electrochemical oxidation of methanol, ethanol and glycerol. In all cases, the Pt25-Ru25-(TiO2)50 electrode had better electrocatalytic activity than the pure Pt50-Ru50 anode. The best modified electrode, (Pt25-Ru25-(TiO2)50), was also evaluated as anode in a PEM fuel cell under methanol fuelling conditions. The observed higher performance of the TiO2 modified electrodes was attributed to the enhanced Pt-Ru dispersion as well as the formation of smaller Pt and Ru particles.

Composites of silica with immobilized cholinesterase incorporated into polymeric shell.

Synthetic approaches for new nanocomposite materials with relatively high cholinesterase activity have been developed. The peculiarity of the formation of such systems is the introduction of cholinesterase into polymer with subsequent incorporation on the ready-made silica particles and into the polysiloxane matrixes during sol-gel synthesis. Evaluation of the cholinesterase activity has been fulfilled through the imitation of the acetylcholine chloride decomposition reaction. Values of activity for cholinesterase nanocomposites demonstrated in this work are higher than those for the native cholinesterase. The higher activity of cholinesterase contained in nanocomposites was found for those prepared using highly dispersed silica.

Nanostructured amorphous nickel oxide with enhanced antioxidant activity

Nanostructured amorphous nickel oxide was synthesized by the thermal decomposition of nickel chloride–ethanol amine complex. The X-ray diffraction and Transmission Electron Microscopic studies established the amorphous nature of the sample. The Fourier Transform Infrared, Scanning Electron Microscopy, Energy Dispersive and X-ray Photoelectron Spectroscopic studies of the sample revealed the formation of NiO. The specific surface area of the sample is measured using Brunauer–Emmett–Teller analysis and the mesoporous nature of the sample is established through Barrett–Joyner–Halenda pore size distribution analysis. The antioxidant activity of the amorphous sample measured by 1,1-diphenyl-2-picryl hydrazyl (DPPH) scavenging is found to be nearly twice greater than that reported for nanocrystalline NiO samples. The estimated radical scavenging activity of the sample is correlated with the DC conductivity values measured in vacuum and air ambience. The enhanced antioxidant activity of the amorphous NiO is accounted by the increase in the concentration of O2− vacancies and the specific surface area. The Ni 2p and O 1s X-ray Photoelectron Spectroscopic studies of the sample support the inference.

Development of Ti/(RuO2)0.8(MO2)0.2 (M=Ce, Sn or Ir) anodes for atrazine electro-oxidation. Influence of the synthesis method

Binary dimensionally stable anodes (DSA) containing RuO2 and/or IrO2, SnO2, CeO2 were prepared by the Pechini method as well as by the thermal decomposition of metallic chlorides dissolved in an ionic liquid (IL). Both, the synthesis method and the chemical composition, were crucial in the catalytic activity of the DSAs towards atrazine oxidation. The highest electrocatalytic activity towards atrazine oxidation (~100%) was obtained by the Ti/(RuO2)0.8(IrO2)0.2 electrode synthesized by using an IL as solvent (IL method), and it was mainly due to the high catalytic activity of RuO2 and IrO2 towards the oxidation of organic compounds allied to the very rough surface obtained by the IL method.

Enhancement of magnetic heating efficiency in size controlled MFe2O4 (M = Mn, Fe, Co and Ni) nanoassemblies

The MFe2O4 magnetic nanoparticle nanoassemblies (MNNAs) have been synthesized via thermal decomposition of metal chloride in ethylene glycol (EG) in the presence of ethylenediamine (EDA).

Influence of Potassium Chloride on the Thermal Decomposition of Ammonium Nitrate

The thermal decomposition of ammonium nitrate (AN), activated carbon (AC), and potassium chloride (KCl) mixtures are investigated. The thermal properties were studied using differential scanning calorimetry (DSC) and the evolved gas was analyzed using thermogravimetry with mass spectroscopy (TG-DTA-MS). The time to maximum rate (TMRad) was then calculated using commercial thermal analysis software. DSC measurements of an AN/KCl mixture in a sealed sample pan showed a sharp exothermic decomposition and lower onset temperature than pure AN, whereas AN/KCl in an open pan exhibited an endothermic reaction. A mixture of AN/AC/KCl exhibited a lower onset temperature than both AN/AC and AN/KCl. TG-DTA-MS results revealed HCl gas was evolved from AN/KCl, which indicated the reaction of KCl with HNO3 dissociated from AN to form HCl, and the subsequent destabilization of AN and AN/AC by HCl. TMRad calculations showed that AN/KCl underwent a run-away reaction within one day under closed adiabatic conditions above 180°C.

Mössbauer spectroscopy studies of the magnetic properties of ferrite nanoparticles

Studies of the ferrite nanoparticles prepared by the chemical decomposition of iron chlorides with a various ratio ξ = Fe3+/Fe2+ are herein presented. The microstructure and the magnetic properties have been studied by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Mössbauer spectroscopy (MS). The TEM studies show that the nanoparticles have almost a spherical shape with the diameter of (12 ± 2) nm for all samples. The measured XRD pattern was mainly composed of lines which were indexed with a cubic spinel structure. The analysis of the Mössbauer data shows that the microstructure of the nanoparticles consists of the core formed by nonstoichiometric magnetite and maghemite shell. A small amount of hematite, probably on the surface of the nanoparticles with ξ = 1.75, 2.0, was detected. At temperatures T ≤ 150 K the spin canting of surface maghemite with ξ = 2.25 was observed while for the samples with ξ = 1.75, 2.0 such effect was suppressed by the presence of hematite on the surface of the nanoparticles. Infield Mössbauer spectra with ξ = 1.75, 2.0 show that magnetic moments of the magnetite/maghemite core are parallel while magnetic moments of the surface hematite are perpendicular to the direction of the external magnetic field.

Cyanuric chloride reagent as a chloride ion donor: synthesis, crystal structure, and magnetic properties of [Cu2(2-APM)2(μ-Cl)2(μ-OCH3)2]n coordination polymer

A new chloro- and methoxo-bridged Cu(II) coordination polymer, [Cu2(2-APM)2(μ-Cl)2(μ-OCH3)2]n·CH3OH (1), was prepared using in situ formed chloride by the decomposition of cyanuric chloride and 2-aminopyrimidine (2-APM) as a ligand in methanol. Its solid-state structure has been characterized by elemental analysis and single crystal X-ray diffraction. X-ray crystallographic studies reveal that this compound has an extended 2-D supramolecular architecture directed by strong hydrogen bonds and aromatic π–π stacking interactions. Compound 1 shows an antiferromagnetic coupling exchange with coupling constants of −58.2 and −41.4 cm−1 between adjacent copper(II) ions, in agreement with the intermetallic distances of 3.0405(5) and 3.6073(5) Å found in the crystal structure.

Investigating the Composition and Electrochemical Activity of Ti/SnO2-Sb2O5 Anodes Fabricated by Thermal Decomposition

Antimony-doped tin oxide anodes were fabricated from the thermal decomposition of tin chloride and antimony chloride. The surface and in-depth distribution of elemental compositions were analyzed using photoelectron spectroscopy. The results suggested that during the thermal treatment of the anodes, antimony preferentially was lost by evaporation, resulting in a composition that deviated from that nominally expected. Further electrochemical tests revealed that the composition in the antimony-doped tin oxide coatings had an impact on the conductivity of the anodes. Therefore, this study reveals that the evaporation loss of the precursor had an impact on the electrochemical activity of the antimony-doped tin oxide anodes.

Structural, magnetic, and electronic properties of iron selenide Fe6-7Se8 nanoparticles obtained by thermal decomposition in high-temperature organic solvents.

Iron selenide nanoparticles with the NiAs-like crystal structure were synthesized by thermal decomposition of iron chloride and selenium powder in a high-temperature organic solvent. Depending on the time of the compound processing at 340 °C, the nanocrystals with monoclinic (M)-Fe3Se4 or hexagonal (H)-Fe7Se8 structures as well as a mixture of these two phases can be obtained. The magnetic behavior of the monoclinic and hexagonal phases is very different. The applied-field and temperature dependences of magnetization reveal a complicated transformation between ferrimagnetic (FRM) and antiferromagnetic (AFM) structures, which can be related to the spin rotation process connected with the redistribution of cation vacancies. From XRD and Mössbauer data, the 3c type superstructure of vacancy ordering was found in the hexagonal Fe7Se8. Redistribution of vacancies in Fe7Se8 from random to ordered leads to the transformation of the magnetic structure from FRM to AFM. The Mössbauer data indicate that vacancies in the monoclinic Fe3Se4 prefer to appear near the Fe(3+) ions and stimulate the magnetic transition with the rotation of the Fe(3+) magnetic moments. Unusually high coercive force Hc was found in both (H) and (M) nanocrystals with the highest ("giant") value of about 25 kOe in monoclinic Fe3Se4. This is explained by the strong surface magnetic anisotropy which is essentially larger than the core anisotropy. Such a large coercivity is rare for materials without rare earth or noble metal elements, and the Fe3Se4-based compounds can be the low-cost, nontoxic alternative materials for advanced magnets. In addition, an unusual effect of "switching" of magnetization in a field of 10 kOe was found in the Fe3Se4 nanoparticles below 280 K, which can be important for applications.

Thermodynamics and kinetics of the thermal decomposition of cupric chloride in its hydrolysis reaction

The hydrolysis of copper(II) chloride is the water splitting process in the copper–chlorine thermochemical hydrogen production cycle. In this paper, a simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC/TG) technique is used to determine the transitional temperature and kinetics of the thermal decomposition of CuCl2. Thermodynamic analysis is performed on the decomposition reaction for a comparison with the thermogravimetric analysis results. The CuCl2 decomposition temperature obtained from thermogravimetric experiments is found to be higher than that predicted from the thermodynamic analysis. This broadens the available operating temperature range of the CuCl2 hydrolysis step for the Cu–Cl cycle. It is also found that the decomposition product CuCl may completely evaporate if the temperature is higher than its melting point, so the CuCl2 hydrolysis reaction should be operated below the melting point of CuCl (430 °C) to avoid the undesirable CuCl and Cl2 byproducts. A preliminary correlation is proposed in this paper for the decomposition kinetics in terms of the extent of converting CuCl2 to CuCl and Cl2.

XPS Investigation of Loss of Antimony in the Thermal Preparation of the Ti/SnO2-Sb2O5 Anode

Introduction The Ti/SnO2-Sb2O5 anode was found to be suitable for the electro-oxidation of organics in municipal wastewater, due to its low cost, high efficiency and strong oxidation power1. Similar to other anodes of metal-oxides on titanium, it can be prepared by the thermal decomposition of metal chlorides on a titanium substrate, but this method suffers the loss of oxides by the evaporation of the chloride salts2, which is particularly serious with the Ti/SnO2-Sb2O5 anode.The present work focused on investigating this problem, using XPS to explore the surface and in-depth profiles of the coating film. Experimental Methods The Ti/SnO2-Sb2O5 anodes were prepared by methods modified from literature1,3. An isopropanol solution of SbCl3 and SnCl4·5H2O mixed at a target composition (Sb:Sn) was brush coated onto a polished Ti surface. The coated anodes were then heated slowly to 500°C in 2 hours to finish the conversion from chlorides to oxides.XPS analysis was conducted on the fabricated anodes. The spectra were analyzed and quantified, using powdered SnO2, Sb2O3 and Sb2O5 as external standards. The Sn3d5/2, Sb3d3/2 and O1s peaks were used for quantification. The O1s peak was processed by subtracting the overlapping Sb3d5/2 signal and then deconvoluting into 3 sub-peaks. Oxygen in the metallic oxide lattice had the lowest binding energy and also the highest intensity, and it was used for quantification. In-depth profiling was performed with angle resolved XPS and with XPS under simultaneous Ar+ ion etching. Results and Discussions Fig 1(a) summarizes the measured composition from XPS versus the target composition expected from the coating solution in some samples, with black dots representing the electrodes prepared by the present method. Fig 1(b) shows that the majority of the Sb was in the 5+ state.The measured Sb/Sn ratio was much lower than the target and was randomly distributed. The loss of Sb was suspected to be caused by the vaporization of SbCl3 from the coated anodes. Unlike SnCl4·5H2O which only decomposes under the temperatures used, SbCl3 can vaporize at 220°C. Therefore during the heating, the element of Sb may undergo both evaporation and oxidation. Evaporation potentially can occur at a lower temperature than oxidation and result in significant loss of Sb prior to the oxide film formation. To test this hypothesis, another piece of Ti/SnO2-Sb2O5 was prepared and heated rapidly to 500°C. Rapid heating should reduce evaporation, and indeed the resulting film was found to retain more Sb (Fig 1(a) red square marker).In-depth profiles of Sb/Sn were analyzed investigate the distribution of Sb in the film. Angle-resolved XPS (Fig1(c)) showed an increase in the Sb/Sn ratio with tilted viewing angle towards the surface. XPS with Ar+ ion etching also showed that Sb was detected only within the top 5nm of the material. It can be deduced that the antimony was concentrated at the surface. This could be of concern as the Sb may not effectively dope the SnO2 to lower its conductivity. Conclusions and Future Work XPS revealed the loss and surface concentration of Sb in Ti/SnO2-Sb2O5 anodes. These were probably associated with the vaporization of SbCl3 during the electrode fabrication which is undesirable in the pyrolytic preparation of this electrode. Future work will be on the electro-deposition method as a substitute to produce adhering films of controllable Sb/Sn compositions. References L. Lipp and D. Pletcher, Electrochim. Act. 42 1091 (1997)Ch.Comninellis and G.P.Vercesi, J. App. Electrochem. 21 136 (1991)Q. Ni, D. W. Kirk, S. J. Thorpe, ECS Trans. 50(19) 87 (2013)

Structural features of nanocrystalline holmium oxide prepared by the thermal decomposition of organic precursors

Powders of nanostructured holmium oxide (C-Ho2O3) with the crystallite sizes ranging from 6 to 16nm have been prepared in bulk from the thermal decomposition of holmium acetate and carbamide-containing complex of holmium as precursors at 600 and 700°C. The powders obtained have been investigated by X-ray diffraction, TEM, thermogravimetry, IR- and Raman spectroscopy. A comparison has been drawn between these and powdered holmium oxide with micron-sized crystallites prepared from the thermal decomposition of holmium chloride. The bcc lattice parameter of the oxides has been found to increase when the crystallite size decreases. It has been noted that the surface of air-exposed powders of holmium oxides is covered by products formed due to the chemisorption of atmospheric CO2 and H2O molecules.

Quantitative Model of Interactions in the Thermal Decomposition of Key Refuse-Derived Fuel Components

Advanced thermal treatment of refuse-derived fuels (RDFs) necessitates accurate determination of the key component fractions and comprehensive understanding of the decomposition characteristics during thermal conversion. In this paper, the linear weighted sum method is employed to retrieve mass fractions of key components in different municipal solid waste (MSW)-derived fuel pellets through thermogravimetric (TG) analysis. A new Gaussian-fitting-based adjusting model is proposed to quantitatively assess the effect of the interaction on the decomposition of individual components based on differential thermogravimetric (DTG) analysis. Results show that the mass fractions of combustible key components can be determined from DTG curves and by applying the Gaussian-fitting-based adjusting model, the effects of the interaction on the decomposition of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and cellulose can be identified. It is found that, after mixing PE into RDFs, both the reaction time and activation energy of PE are decreased. The degradation of PVC starts at a higher temperature within the temperature range from 200 to 380 °C, and its reaction time is decreased by 50% within the temperature range from 380 to 500 °C. The activation energy of cellulose is slightly increased. The model proposed in this paper could be a promising method to evaluate the interaction between different key components in mixed samples for optimizing the parameters of the thermal conversion system.

Modeling of ferric sulfate decomposition and sulfation of potassium chloride during grate‐firing of biomass

Ferric sulfate is used as an additive in biomass combustion to convert the released potassium chloride to the less harmful potassium sulfate. The decomposition of ferric sulfate is studied in a fast heating rate thermogravimetric analyzer and a volumetric reaction model is proposed to describe the process. The yields of sulfur oxides from ferric sulfate decomposition under boiler conditions are investigated experimentally, revealing a distribution of approximately 40% SO3 and 60% SO2. The ferric sulfate decomposition model is combined with a detailed kinetic model of gas‐phase KCl sulfation and a model of K2SO4 condensation to simulate the sulfation of KCl by ferric sulfate addition. The simulation results show good agreements with experiments conducted in a biomass grate‐firing reactor. The results indicate that the SO3 released from ferric sulfate decomposition is the main contributor to KCl sulfation and that the effectiveness of ferric sulfate addition is sensitive to the applied temperature conditions. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4314–4324, 2013

Ultraviolet-Induced Effects on Chloramine and Cyanogen Chloride Formation from Chlorination of Amino Acids

Ultraviolet (UV)-based treatment is commonly used to augment chlorination in swimming pools. However, the effects of combined application of UV254/chlorine on disinfection byproduct (DBP) formation are incompletely defined. To examine this issue, experiments were conducted with amino acids (l-arginine, l-histidine, and glycine) that are representative of those introduced to swimming pools via human body fluids. For each precursor, stepwise experiments were conducted with chlorination and UV254 exposure, with/without post-chlorination. Net formation and decomposition of chloramines and cyanogen chloride (CNCl) were measured for a range of chlorine/precursor (Cl/P) molar ratios and UV254 doses. Substantial production of NH2Cl from l-arginine and l-histidine was observed at Cl/P = 1.0 and 2.0 when post-chlorination was applied to UV254-irradiated samples. These results suggested a mechanism of rapid N-chlorination, followed by cleavage of NH3 by UV254 irradiation. CNCl formation was observed from UV254-irradiated samples of l-arginine and l-histidine when Cl/P = 2.0 and 3.0, as well as from glycine for Cl/P ≤ 1. Structurally related precursor compounds were examined for CNCl formation potential in chlorination/UV experiments. CNCl formation was promoted by UV254 exposure of chlorinated imidazole and guanidine compounds, which suggested that these groups contributed to CNCl formation. The results have implications with respect to the application of chlorine and UV for water treatment in swimming pools and other settings, such as water reuse and advanced oxidation processes.

Thermal, spectral, magnetic and antimicrobial behaviour of new Ni(II), Cu(II) and Zn(II) complexes with a hexaazamacrocyclic ligand

New species of type MLCl2·nH2O (M:Ni, n = 6; M:Cu, n = 1.5 and M:Zn, n = 1; L: 1,8-bis(3′-ketopyridil)-1,3,6,8,10,13-hexaazacyclotetradecane, ligand resulted by 1,2-diaminoethane, nicotinamide and formaldehyde template condensation) were synthesised. The compounds were characterised by chemical analysis, ESI–MS, IR, NMR, UV–Vis-NIR and EPR spectroscopy as well as magnetic data at room temperature. The modifications in the IR and NMR spectra are in accordance with the condensation process. Electronic spectra indicate that Ni(II) adopts an octahedral stereochemistry while the surrounding of Cu(II) is square-pyramidal. The proposed stereochemistry was furthermore confirmed by magnetic moments and EPR spectrum at room temperature. The water is eliminated in one or two steps, respectively, while the oxidative degradation of the ligand and chloride decomposition occur in two steps. The final residues consist of the most stable metallic oxides as X-ray powder diffraction indicates. The newly synthesised compounds were evaluated for their antimicrobial effect against different bacterial and fungal strains.

The effect of pre-heating on the kinetics of the thermal decomposition of pure and chloride and phosphate doped sodium oxalate

The effect of pre-heating on the kinetics of the thermal decomposition of pure and chloride and phosphate doped sodium oxalate has been studied, as a function of the time of pre-heating, at a temperatures of 783K under isothermal conditions by thermogravimetry (TG). The model fitting analysis of the TG data shows that no single kinetic model describes the whole α versus t curve with a single rate constant throughout the decomposition reaction; Prout–Tompkins model best describes the acceleratory stage of the decomposition while the decay region is best fitted with the contracting cylinder model. The rates of both stages were decreased by pre-heating for 24–36h and then remained constant. Pre-heating of sodium oxalate resulted in a significant decrease in the rate of thermal decomposition and the general nature of the effects of dopants remains unaffected in both stages of the thermal decomposition reaction.