Electrochemical Characterization and Application of Carbon Ionic Liquid Electrodes Containing 1 : 12 Phosphomolybdic Acid

1 : 12 Phosphomolybdic acid (PMo₁₂) and graphite powder were homogeneously dispersed into an n‐octylpyridinum hexafluorophosphate base carbon ionic liquid electrode (CILE). The cyclic voltammograms of the PMo₁₂ modified CILE showed three well‐defined pairs of redox peaks due to the PMo₁₂ system. Formal potentials and electrochemical characteristics including electron transfer rate constant and transfer coefficient were evaluated. Additionally, PMo₁₂ modified CILE exhibited good electrocatalytic activity toward iodate reduction. The kinetic of catalytic reduction of iodate on PMo₁₂ modified CILE was investigated in detail. The modified electrode was used for amperometric determination of iodate in commercial table salt.     

Dry Reforming of Methane by DC Spark Discharge with a Rotating Electrode

A novel type of plasma reactor having a rotating electrode is proposed for CO₂ reforming of methane without catalyst at room temperature and atmospheric pressure. Results indicated that employing rotating ground electrode leads to a stable discharge for any period of time. Effects of feed composition, feed flow rate, applied power and electrodes separation on the carbon dioxide and methane conversions as well as the products selectivity were investigated. Increasing CO₂/CH₄ molar ratio in the feed favors the reagents conversion and consequently promotes the formation of hydrogen and carbon monoxide. If the target product is hydrogen, it is proposed to operate the reactor at CO₂/CH₄ = 1 molar ratio and if the target product is carbon monoxide then CO₂/CH₄ = 3 molar ratio is the preferred option for feed composition. This reactor system has advantages of stable operation and high conversion ability. Also, the obtained syngas with flexible molar ratio of H₂ to CO is suitable for vast industrial applications.     

Sensitive and selective determination of hydrazine using glassy carbon electrode modified with Pd nanoparticles decorated multiwalled carbon nanotubes

A glassy carbon electrode modified with palladium nanoparticles decorated multiwalled carbon nanotubes (GCE/nanoPd-MWCNTs) was fabricated. Incorporation of palladium nanoparticles onto the carbon nantube surface by thermal decomposition of palladium acetate led to the fabrication of a sensor with a significant decrease in hydrazine electrooxidation potential. The sensor exhibited low detection limits, high sensitivity and selectivity, rapid response, and good stability toward hydrazine detection.     

Experimental and thermodynamic modelling of systems containing water and ethylene glycol: Application to flow assurance and gas processing

Accurate knowledge of hydrate phase equilibrium in the presence of inhibitors is crucial to avoid gas hydrate formation problems and to design/optimize production, transportation and processing facilities. In this communication, we report new experimental dissociation data for various systems consisting of methane/water/ethylene glycol and natural gas/water/ethylene glycol. A statistical thermodynamic approach, with the Cubic-Plus-Association equation of state, is employed to model the phase equilibria. The hydrate-forming conditions are modelled by the solid solution theory of van der Waals and Platteeuw. The thermodynamic model was used to predict the hydrate dissociation conditions of methane and natural gases in the presence of distilled water or ethylene glycol aqueous solutions. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model.     

Application of resin and NH4NO3 as an ion exchange agent for microspherical preparation of nanostructured kaolin-SAPO-34 catalyst for methanol to light olefins reaction in a fluidized bed reactor

Research on Chemical Intermediates - The aim of this research is to investigate the influence of various ion exchange methods in the assembly of nanostructured kaolin-SAPO-34 catalyst using silica...     

Sufficient conditions for a linear functional to be multiplicative

A commutative Banach algebra is said to have the property if the following holds: Let be a closed subspace of finite codimension such that, for every , the Gelfand transform has at least distinct zeros in , the maximal ideal space of . Then there exists a subset of of cardinality such that vanishes on , the set of common zeros of . In this paper we show that if is compact and nowhere dense, then , the uniform closure of the space of rational functions with poles off , has the property for all . We also investigate the property for the algebra of real continuous functions on a compact Hausdorff space.

     

Spectrophotometric reaction rate method for the determination of molybdenum by its catalytic effect on the oxidation of pyrogallol red with hydrogen peroxide

A kinetic spectrophotometric method for the determination of molybdenum is based on its catalytic effect on the oxidation of pyrogallol red with hydrogen peroxide. The decrease of the absorbance of pyrogallol red in the presence of hydrogen peroxide with time from 0.5 to 4.5 min is proportional to the concentration of Mo(VI) over the range 0.010–0.500 μg/mL. The limit of detection is 0.008 μg Mo/mL. The precision and the effect of the presence of more than forty ions on the molybdenum determination are reported. Probable interferences are completely removed by a cation exchange resin. The procedure was successfully applied to the determination of molybdenum in plant materials and steels. Received: 28 April 1997 / Revised: 16 June 1997 / Accepted: 18 June 1997     

Effect of Various Deposition Techniques,Electrode Materials and Posttreatment with Tetrabutylammonium and Tetrabutylphosphonium Salts on the Electrochemical Behavior and Stability of Various Prussian Blue Modified Electrodes

The effect of various deposition techniques, electrode materials and posttreatment with tetrabutylammonium and tetrabutylphosphonium salts on the electrochemical behavior and stability of various Prussian blue (PB) modified electrodes, namely PB modified glassy carbon electrodes, silicate‐film supported PB modified glassy carbon electrodes, PB‐doped silicate glassy carbon electrodes, PB modified carbon ceramic electrodes using electrochemical deposition and PB modified carbon ceramic electrodes using chemical deposition is reported. Cyclic voltammetry and amperometric measurements of hydrogen peroxide were performed in a flow injection system while the carrier phosphate buffer (pH 7.0) with a flow rate of 0.8 mL min^?1 was propelled into the electrochemical flow through cell housing the PB modified working electrode as well as an Ag|AgCl|0.1 M KCl reference and a Pt auxiliary electrode. The results showed that the deposition procedure, electrode material and posttreatment with additional chemicals can significantly alter the stability and electrochemical behavior of the PB film. Among the studied PB modified electrodes, those based on carbon ceramic electrodes modified with a film of electropolymerized PB showed the best electrochemical stability.     

Spektroskopische Eigenschaften von Di(phthalocyaninato)metallaten(III) der Seltenen Erden Teil 1: Elektronische Absorptionsspektren und Schwingungsspektren

Spectroscopical Properties of Di(phthalocyaninato)metalates(III) of the Rare Earth Elements. Part 1: Electronic Absorption and Vibrational Spectra Di(phthalocyaninato)metalates(III) of the rare earth elements were prepared by the reaction of partially dehydrated lanthanide acetate with molten phthalodinitrile in the presence of potassium methylate and isolated as complex salts with different tetraalkylammonium cations, especially tetra(n-butyl)- and tri(n-dodecyl)n-octylammonium and di((triphenyl)phosphine)-iminium (abbrev.: (ⁿBu₄N), TDOA, PNP). Besides the typical strong π-π* transitions in the B, Q, N regions of the Pc^2? ligands low intensity bands at ca. 10, 11 and 19 kK are observed in the UV-Vis-NIR spectra and assigned to singulet–triplet transitions. In going from La to Lu the B band splits continously due to excitonic coupling extending from 0,71 (La) to 1,92 kK (Lu). The FIR-MIR and resonance Raman spectra are nearly metal independent with the exception of some hypsochromically shifted bands due to C? C and C? N stretching and deformation vibrations of the inner (CN)₈ ring. Only the FIR band at 157 cm^?1 (La) assigned to the asym. Ln? N stretching vibration is shifted to lower energy.     

Prussian blue modified glassy carbon electrodes-study on operational stability and its application as a sucrose biosensor

Stabilisation of electrochemically deposited Prussian blue (PB) films on glassy carbon (GC) electrodes has been investigated and an enhancement in the stability of the PB films is reported if the electrodes are treated with tetrabutylammonium toluene-4-sulfonate (TTS) in the electrochemical activation step following the electrodeposition. A multi-enzyme PB based biosensor for sucrose detection was made in order to demonstrate that PB films can be coupled with an oxidase system. A tri-enzyme system, comprising glucose oxidase, mutarotase and invertase, was crosslinked with glutaraldehyde and bovine albumin serum on the PB modified glassy carbon electrode. The deposited PB operated as an electrocatalyst for electrochemical reduction of hydrogen peroxide, the final product of the enzyme reaction sequence. The electrochemical response was studied using flow injection analysis for the determination of sucrose, glucose and H₂O₂. The optimal concentrations of the immobilisation mixture was standardised as 8 U of glucose oxidase, 8 U of mutarotase, 16 U of invertase, 0.5% glutaraldehyde (0.025 μl) and 0.5% BSA (0.025 mg) in a final volume of 5 μl applied at the electrode surface (0.066 cm²). The biosensor exhibited a linear response for sucrose (4-800 μM), glucose (2-800 μM) and H₂O₂ (1-800 μM) and the detection limit was 4.5, 1.5 and 0.5 μM for sucrose, glucose and H₂O₂, respectively. The sample throughput was ca. 60 samples h⁻¹. An increase in the operational and storage stability of the sucrose biosensor was also noted when the PB modified electrodes were conditioned in phosphate buffer containing 0.05 M TTS during the preparation of the PB films.