An efficient copper mediated synthetic methodology for benzo[d]isothiazol-3(2H)-ones and related sulfur–nitrogen heterocycles

A copper mediated sulfur–nitrogen coupling reaction for the synthesis of benzo[d]isothiazol-3(2H)-ones and related sulfur–nitrogen heterocycles has been presented, which requires 2-halo-arylamides, sulfur powder, 25–50 mol % of copper iodide/1,10-phenanthroline, and potassium carbonate as base.     

Analysis of the Rheological Behavior of Copper Metal Injection Molding (MIM) Feedstock

Metal Injection Molding (MIM) technique allows for the production of highly porous metallic foams with porosity levels up to 90%. It makes use of the pressure built up by the decomposition of a foaming agent which is incorporated in a foamable precursor copper material obtained by powder compaction. Rheological is one of the key factors to ensure the successful of MIM technique and to predict failure, whether due to the binder component and compositions, powder loading or unsuitable process parameters. The balanced ratio feedstock contains of 63 vol.% of copper powder, different percentage of potassium carbonate; Batch 1 (0.4 vol.%), Batch 2 (0.5 vol.%) and Batch 3 (0.6 vol.%), and the remaining volume percentage of binder system has been mixed to form copper feedstock. The rheological behaviors were investigated using a capillary rheometer (CFT-500D, Shimadzu) at various temperature and loads. From the experiments, it was concluded that the MIM feedstock exhibit a shear thinning or pseudo-plastic behavior based on the trend of graph which is suitable for MIM process. This result is within the ideal range of viscosity theoretical for MIM feedstock which is in the range of between 10 Pa.s to 1000 Pa.s at all temperature tested. The viscosity of a pseudo-plastic substance decreases as the shear rate increases (shear thinning). This could be due to particle orientation and ordering with flow as well as breakage of particle agglomerates released together with the binder.     

Electrically rechargeable zinc-oxygen flow battery with high power density

The development of a powerful, cyclically stable and electrically rechargeable zinc-oxygen battery with a three-electrode configuration is reported. A copper foam was used as stable substrate for zinc deposition in flowing potassium hydroxide electrolyte, while oxygen reduction and evolution were accomplished by a commercial silver electrode and a nickel foam, respectively. The cell could be charged and discharged with up to 600 mA cm^− 2, delivered a peak power density of 270 mW cm^− 2, and performed for more than 600 cycles, although short circuits by dendrite formation could not yet be completely avoided. At a current density of 50 mA cm^− 2 and a temperature of 30 °C, a promising energy efficiency of 54% was achieved.     

Development of novel low-temperature SOFCs with co-ionic conducting SDC-carbonate composite electrolytes

A series of ceria-based composite materials consisting of samaria doped ceria (SDC) and binary carbonates(Li₂CO₃–Na₂CO₃) were examined as functional electrolytes for low-temperature solid oxide fuel cells (SOFCs). DTA and SEM techniques were applied to characterize the phase- and micro-structural properties of the composite materials. Conductivity measurements were carried on the composite electrolytes with a.c. impedance in air. A transition of ionic conductivity with temperature was occurred among all samples with different carbonate content, which related to the interface phase. Single cells based on the composite electrolytes, NiO as anode and lithiated NiO as cathode, were fabricated by a simple dry-pressing process and tested at 400–600 °C. The maximum output power at 600 °C increased with the carbonate content in the composite electrolytes, and reached the maximum at 25 wt.%, then decreased. Similar trend has also shown at 500 °C, but the maximum was obtained at 20wt.%. The best performances of 1085 mW cm⁻² at 600 °C and 690 mW cm⁻² at 500 °C were achieved for the composite electrolytes containing 25 and 20 wt.% carbonates, respectively. During fuel cell operation, it found that the SDC-carbonate composites are co-ionic (O²⁻/H⁺) conductors. At lower carbonate contents, both oxide–ion and proton conductions were significant, when the content increased to 20–35 wt.%, proton conduction dominated. The detailed conduction mechanism in these composites needs further investigation.     

Effect of NaCl as a Space Holder in Producing Open Cell A356 Aluminium Foam by Gravity Die Casting Process

Gravity die casting is the technique which enables fabrication of open-cell A356 aluminium foam as a suitable absorber material with good quality performance. A356 aluminium alloy was used with varies amount of sodium chloride (NaCl) particles as a space holder to fabricate the aluminium foam using gravity die casting. Microstructural analysis, porosity and density were investigated in this study. As the addition of the NaCl space holder increases, porosity increases leading to decreasing density of the foam. Aluminium foam with 30 wt.% NaCl showed moderate porosity among the others foam.     

Effect of electron beam radiation dose on the foam formation in pre-ceramic polymer

Methylsilicone resin as a polymer precursor for a SiOC ceramic material was cured and foamed by electron beam (EB) irradiation in air prior to the pyrolysis under an inert atmosphere. Methylsilicone foams were obtained without additional foaming agent when exposed to accelerated electrons with radiation doses up to 9 MGy and dose rate of 2.8 kGy/s. During irradiation the polymer was melted and simultaneously gaseous products were formed by the methyl group oxidation and by the poly-condensation crosslinking reactions. The formed gases could not escape from the molten polymer and began to aggregate into bubbles. The effect of the radiation dose on the polymer foam molecular structure, the gel fraction and the ceramic yield was analyzed. The results indicate that the maximum amount of crosslinking in methylsilicone, when EB radiation is used, occurred between 1.0 and 2.0 MGy radiation dose. Methylsilicone foams were pyrolysed in N₂ atmosphere at temperatures of 1200 and 1500 °C, resulting in amorphous SiOC and partially crystalline ceramic foams, respectively. A porosity of ~84% was achieved in the pyrolyzed foams, with cell size ranging from 30 to 300 μm and density of about 0.31 g cm^?3.     

The effect of copper content on the reactivity of Cu/Co6Al2 solids in the catalytic steam reforming of methane reaction

The steam reforming of methane over Cu/Co₆Al₂ mixed oxides with different copper contents was studied. The Co₆Al₂ support was prepared via the hydrotalcite route. It was thermally stabilized at 500 °C, impregnated with 5 wt.%, 15 wt.% or 25 wt.% copper using copper (II) nitrate Cu(NO₃)₂·3H₂O precursor and then calcined again at 500 °C under an air flow. The impregnation of copper enhanced significantly the reactivity of the solids in the considered reaction. The 5Cu/Co₆Al₂ solid was the most reactive one, with a methane conversion of 96% at 650 °C. The selectivities of H₂ and CO₂ were also better for the catalyst containing 5 wt.% copper compared to higher copper loadings. The decrease in the catalytic reactivity with increasing the copper content was attributed to the formation of agglomerated and less reactive CuO species, which were detected by XRD and TPR analyses.     

Polysulfone — sulfonated poly(ether ether) ketone blend membranes: systematic synthesis and characterisation

The effect of sulfonated poly(ether ether ketone) (SPEEK) in membrane formation and separation properties has been investigated in polysulfone(PSU)/SPEEK/N-methyl-2-pyrrolidinone (NMP) systems. Charged ultrafiltration/nanofiltration membranes were obtained reliably in the range of 0.5–5 wt.% SPEEK in the polymer blend. All PSU/SPEEK blend membranes had substantially higher water flux, salt rejection, porosity and greatly reduced particle adhesion compared to the PSU base membrane. Further, all of these properties varied systematically with variation of SPEEK content. Reproducibility and stability of the membrane properties was excellent. Pore sizes determined from dextran retention data and AFM measurements showed reasonable agreement. Membranes with 5 wt.% SPEEK demonstrated excellent overall properties. Such membranes had very high permeability, 22.6±1.6×10⁻¹¹ m³ s⁻¹ N⁻¹, 0.999 fractional rejection of 4000 Da dextran, 0.65 rejection of 0.001 M NaCl, and only 0.75 mN m⁻¹ adhesion of a 4 μm silica particle. Such membranes are very promising for scale-up of production and testing on real process streams.     

Understanding the nature of vanadium species supported on activated carbon and its catalytic properties in the aerobic oxidation of aromatic alcohols

Vanadium oxide catalysts supported on activated carbon (V/AC) with V loadings ranging from 1 to 20 wt.% were prepared by a wet-impregnation method. Various physicochemical characterization techniques, including nitrogen physisorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray absorption (XANES and EXAFS), X-ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR), were employed to understand the nature of vanadium species on activated carbon. The results revealed that vanadium oxide mainly existed in a highly dispersed state for 10 wt.% or less vanadium loadings; a large amount of vanadium resulted in aggregated microcrystalline phase. Vanadium species on activated carbon surface showed a similar local coordination structure to that of NH₄VO₃ with a distorted tetrahedral symmetry at low vanadium loadings, whereas octahedral coordination was dominant at high vanadium loadings (>10 wt.%). All V/AC samples showed V⁵⁺ as the major oxidation state. Nevertheless, V⁴⁺ centered in a distorted tetrahedral symmetry could be detected at a vanadium loading greater than 4 wt.%. The catalytic activity for the benzyl alcohol oxidation largely depended on the dispersion, oxidation state, and local coordination of vanadium oxides on activated carbon. Highly dispersed vanadium (5+) species with a distorted tetrahedral coordination were postulated to account for the excellent catalytic performances of V/AC catalysts (TOF = 39.1 h^?1).     

The improvement of the Li-ion insertion behaviour of Li1.05Cr0.10Mn1.85O4 in an aqueous medium upon addition of vinylene carbonate

The influence of vinylene carbonate addition to aqueous LiNO₃ solution on the Li-ion insertion performance of a Li_1.05Cr_0.10Mn_1.85O₄ was studied by galvanostatic charging/discharging. Without additive, the coulombic capacity amounted initially to 80 mA h g^?1 and, during 50 galvanostatic charging/discharging cycles, decreased to 44.1% of the initial value. Upon VC addition in an amount of 1 wt.%, the initial discharge capacity of 112 mA h g^?1 was registered which after 100th charging/discharging cycles retained even 82% of the initial value. This is the first report of a successful use of an additive to improve the behaviour of a Li-intercalation material in an aqueous solution.     

Effects of CuO addition to anode on the electrochemical performances of cathode-supported solid oxide fuel cells

A cathode-supported electrolyte film was fabricated by tape casting and co-sintering techniques. (La_0.8Sr_0.2)_0.95MnO₃ (LSM95), LSM95/Zr_0.89Sc_0.1Ce_0.01O_2?x (SSZ), and SSZ were used as materials of cathode substrate, cathode active layer, and electrolyte, respectively. CuO–NiO–SSZ composite anode was deposited on SSZ surface by screen-printing and sintered at 1250 °C for 2 h. The effects of CuO addition to NiO–SSZ anode on the performance of cathode-supported SOFCs were investigated. CuO can effectively improve the sintering activity of NiO–SSZ. The assembled cells were electrochemically characterized with humidified H₂ as fuel and O₂ as oxidant. With 4 wt.% CuO addition, the ohmic resistance decreased from 3 to 0.46 Ω cm², and at the same time the polarization resistance decreased from 3.4 to 0.74 Ω cm². In comparison with the cell without CuO, the maximum power density at 850 °C increased from 0.054 to 0.446 W cm^?2 with 4 wt.% CuO addition.     

Product characterization of waste printed circuit board by pyrolysis

This paper is part of a project which studies pyrolysis as an alternative for recycling printed circuit board (PCB); the sample (2.0 cm × 2.0 cm) was pyrolyzed under nitrogen atmosphere, at 300, 400, 500, 600 and 700 °C in a tubular type oven, maintaining 30 min, and during the pyrolysis process the organic part is decomposed to pyro-oils and pyro-gases, which can be used as fuels or chemical material resources: the solid residues of about 75–80 wt.%, liquid yields of ∼9.0 wt.% and gas yields of 12–14 wt.%. No significant influence of temperature was observed over 500 °C, however, there was certainly influence under 500 °C in both volatile substance. The pyro-oils have fairly high gross calorific values (∼30 kJ/kg), mainly with aromatic and with oxygenated compounds. The pyro-gas is very rich in CO, CO₂, H₂, CH₄ and in small part of O₂; after being purged it can be combusted for the pyrolysis self-sustain. The tensile strength decreases about 35% at 773 K, while the impact and tear strength increases above 773 K, and then decreases along with the temperature increase. The strength changes can offer guidance for used as a replacement for virgin fibres in SMC manufacture. The residues are better laminated can be easily liberated for metals recovery.     

Effect of the Different Sr Dopant Contents on NiO Ceramic

Sr - doped NiO ceramic was studied. The effect of composition variation of Ni_(1-x)Sr_xO where x = 0, 0.01, 0.02, 0.03, 0.05 and 0.10 mole % was prepared by using solid state method. The calcination temperature used at 950 °C for 4 hours and the sintering temperature used at 1200 °C for 3 hours. The results depict the microstructures increase in grains size (0.43 - 3.30 μm) by increase of Sr dopant contents. The density and porosity testing support the result of microstructures analysis. The larger grains size led to increase in density and lower in porosity. The dielectric properties is observed in a wide frequency range of (1 - 1 000 MHz). The increase of dielectric constant is associated with the decrease of dielectric loss. The optimum composition was obtained for the x = 0.03 mole % sample with highest dielectric constant (3.24 x 10³) and lowest dielectric loss (1.42) at 1 MHz.     

The Characteristics of Green Calcium Oxide Derived from Aquatic Materials

Thermogravimetric Analysis of three aquatic materials, i.e. cuttlebone, mussel shell and oyster shell, and other physicochemical characteristics were investigated. The highest decomposition rates of aquatic materials under two surrounding gases, i.e. oxygen and nitrogen, exhibited no significant difference for cuttlebone (3.6×10^-5-4.8×10^-5 mg s^-1 mg_initial^-1 at heating rate 5 °C/min and 11.8 ×10^-5 -12.5×10^-5 mg s^-1 mg_initial^-1 at heating rate 15 °C/min) and mussel shell (3.4×10^-5- 5.2×10^-5 mg s^-1 mg_initial^-1 at heating rate 5 °C/min and 11.9×10^-5 – 12.4×10^-5 mg s^-1 mg_initial^-1 at heating rate 15 °C/min), while oyster shell provided the higher decomposition rate under nitrogen surrounding gas (7.6×10^-4 mg s^-1 mg_initial^-1 at heat rate 5 °C/min and 21.53×10^-4 mg s^-1 mg_initial^-1 at heating rate 15 °C/min). This is probably because of the difference in their starting crystalline structures, i.e. aragonite (cuttlebone and mussel shell) and calcite (oyster shell). The cubic calcium oxides were prepared by calcination of three aquatic materials under oxygen and nitrogen surrounding gases at 5 °C/min ramping to 850 °C for 2 hours. All resulting calcium oxides obtained from oxygen atmosphere provided only cubic crystalline phases and the adsorption-desorption isotherms (IUPAC Type III), whereas the calcinations under nitrogen surrounding gas gave a presence of calcium hydroxide crystalline or hydroxyl- contaminate existing with cubic calcium oxide that influences on the strength and the number of carbon dioxide adsorption sites. The specific surface area of all resulting calcium oxides ranged from 0.1 – 1.5 m²/g and the average pore diameter was found in the range of 40-60 nm. The the number of basic sites belonging to CaO derived from Oyster shell or Cuttlebone were improved while firing under oxygen atmosphere. The suitable firing condition is at the low heating rate to develop porous materials.     

Thermally induced transformations of calcium carbonate polymorphs precipitated selectively in ethanol/water solutions

For the precipitation of calcium carbonate polymorphs in ethanol/water solutions of calcium chloride by the diffusion of the gases produced by sublimation–decomposition of solid ammonium carbonate, polymorph selection and morphology control of the precipitates were demonstrated by the effect of ethanol/water ratio in the mother liquor. The precipitated phases change systematically from gel-like aggregates of hydrated amorphous calcium carbonate in the absolute ethanol solution to well-shaped rhombohedral particles of calcite in the absolute aqueous solution via almost pure phase of vaterite with dendrite structure in 75%-ethanol/25%-aqueous and 50%-ethanol/50%-aqueous solutions. On heating the precipitated sample in flowing dry nitrogen, all the samples transformed to calcite before the thermal decomposition, where the thermal decomposition temperature shifts to higher temperatures with increasing the water content in the mother liquor due to the systematic increase in the particle size of calcite. Accordingly, the present method of controlled precipitation of calcium carbonate polymorphs is also useful to control the particle size and reactivity of calcite produced by heating the precipitates. Selecting vaterite with dendrite structure from the present series of precipitated samples, the structural phase transition to calcite was characterized as the three-dimensional growth of rhombohedral particles of calcite with the enthalpy change ΔH = ? 2.8 ± 0.1 kJ mol^?1 and the apparent activation energy E_a = 289.9 ± 5.8 kJ mol^?1.     

Effect of ether group on the electrochemical stability of zwitterionic imidazolium compounds

The cathodic stability of the zwitterionic imidazolium compounds was significantly enhanced by the introduction of an ether group at 1 or 2-position on the imidazolium ring. The cycle performance tests showed that the initial cell capacity was maintained almost unchanged up to 100 cycles at 0.5 and 1 C when 2.5 wt.% of 2-butoxymethyl-1-methylimidazolium-3-propylsulfonate or 2-butoxymethyl-1-butylimidazolium-3-propylsulfonate was added to the model electrolyte (1 M LiPF₆ in ethylene carbonate, dimethyl carbonate and ethylmethyl carbonate (1/1/1 v/v/v)).Structures of zwitterionic compounds and their interactions with lithium ions were theoretically investigated.     

Thermodynamics of aqueous potassium carbonate,piperazine, and carbon dioxide

CO₂ solubility was measured in a wetted-wall column in 0.6–3.6 molal (m) piperazine (PZ) and 2.5–6.2 m potassium ion (K⁺) at 40–110 °C. Piperazine speciation was determined using ¹H NMR for 0.6–3.6 m piperazine (PZ) and 3.6–6.2 m potassium ion (K⁺) at 25–70 °C. The capacity of CO₂ in solution increases as total solute concentration increases and compares favorably with estimates for 7 m (30 wt.%) monoethanolamine (MEA). The presence of potassium in solution increases the concentration of CO₃²⁻/HCO₃⁻ in solution, buffering the solution. The buffer reduces protonation of the free amine, but increases the amount of carbamate species. These competing effects yield a maximum fraction of reactive species at a potassium to piperazine ratio of 2:1.A rigorous thermodynamic model was developed, based on the electrolyte nonrandom two-liquid (ENRTL) theory, to describe the equilibrium behavior of the solvent. Modeling work established that the carbamate stability of piperazine and piperazine carbamate resembles primary amines and gives approximately equal values for the heats of reaction, ΔH_rxn (18.3 and 16.5 kJ/mol). The pK_a of piperazine carbamate is twice that of piperazine, but the ΔH_rxn values are equivalent (∼−45 kJ/mol). Overall, the heat of CO₂ absorption is lowered by the formation of significant quantities of HCO₃⁻ in the mixed solvent and strongly depends on the relative concentrations of K⁺ and PZ, ranging from −40 to −75 kJ/mol.     

Synthesis and structures of N,N,O-scorpionatoruthenium(II) complexes featuring “non-innocent” o-benzoquinonediimines

A series of ruthenium(II) complexes bearing redox-active o-benzoquinonediimines (o-bqdi) was synthesized and characterized. Reactions of [RuCl(bdmpza)(η⁴-cod)] (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetato; cod = 1,5-cyclooctadiene) and 1,2-benzenediamines such as o-phenylenediamine (o-pdaH₂), 4,5-difluoro-1,2-benzenediamine (o-pdaF₂), 4,5-dichloro-1,2-benzenediamine (o-pdaCl₂), and 4,5-dimethoxy-1,2-benzenediamine (o-pda(OMe)₂) afforded [RuCl(bdmpza)(o-bqdiX₂)] (X = H, 1; X = F, 2; X = Cl, 3; X = OMe, 4).     

High temperature oxidative resistance of polyacrylonitrile-methylmethacrylate copolymer powder converting to a carbonized monolith

The doping of polyacrylonitrile (PAN) prior to carbonization can alter the physicochemical nature of the polymer under thermal treatment. The inclusion of a “lower” thermally stable monomer methyl methacrylate (MMA) enables fusion of PAN particles into monoliths and, depending on the heating rate, can control the expansion of the structure and establish pore formation through the volatilization and escape of its thermal degradation products. Moreover, geometry is maintained through the carbonization step, when heated up to 850 °C. The exothermic regime of PAN-co-MMA is much broader and the cyclization reaction starts at a lower temperature compared with that of the PAN homopolymer. TGA reveals that the thermal stability of the copolymer, compared with pure PAN at 800 °C, has increased by 30 wt.% in air, which is far higher than reported in previous studies of copolymers of PAN. The results show promise in providing a facile mechanism for the production of monolithic PAN-based carbons with the potential of controlled porosity.     

Copper(II)–neocuproine reagent for spectrophotometric determination of captopril in pure form and pharmaceutical formulations

A simple, rapid, sensitive and accurate spectrophotometric method for the determination of captopril in pure form and pharmaceutical formulations is developed. The procedure is based on the reaction of copper(II) with captopril in the presence of neocuproine (NC) (2,9-dimethyl-1,10-phenanthroline) reagent in acetate buffer at pH 5.0. Copper(II) is reduced easily by captopril to Cu(I)–neocuproine complex, which shows an absorption maximum at 448 nm. Beer’s law was obeyed in the concentration range 0.3–3.0 μg mL^?1 with a minimum detection limit (LOD) of 0.039 μg mL^?1 and a quantification limit (LOQ) of 0.129 μg mL^?1. For more accurate results, Ringbom optimum concentration ranges was 0.5–2.7 μg mL^?1. The apparent molar absorbtivity and Sandell sensitivity were calculated. The validity of the proposed method was tested by analyzing the pure and pharmaceutical formulations and compared well with those obtained by the official method and demonstrated good accuracy and precision.