Volume 16, Issue 1, 1998
30th May, 2017
STRIPPING VOLTAMMETRY IN ENVIRONMENTAL STUDIES OF DYES AND THIOLS
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by Arnold G.Fogg
5-10
DOI:
A Polarographic, Voltammetric and Coulometric Study of Phenazopyridine Hydrochloride
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by Osman Cakir, Ender Biger
11-23
DOI: doi:10.4152/pea.199801011
The electrochemical properties of phenazopyridine hydrochloride (pyridium) were studied at different pH values in Britton-Robinson buffer solutions by differential pulse and direct current polarography, square wave and cyclic voltammetry, controlled potential coulometry techniques. Polarographic reduction of pyridium takes place in a single 4-electron transfer, giving a diffusion-controlled irreversible wave in the pH range 2.00¬10.50. At high pH values (pH 11.00-12.00), reduction of the compound exhibits a single, 2-electron diffusion-controlled reversible wave. A possible mechanism has been suggested on the basis of the number of electrons involved in the reduction process.
Improving Corrosion Resistance of Aluminium in Acid and Near Neutral Media. Surface Alloying by Ion Implantation
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by M. A. Travassos, C. M. Rangel, R. P. M. Procter
25-42
DOI: doi:10.4152/pea.199801025
New surfaces more resistant to corrosion were produced by ion implantation of W and Ta into aluminium targets. The thermodynamic limitations associated with the low solubility of the solutes were overcome thus increasing the alloying element concentrations to levels necessary to achieve improved corrosion performance. Studies were conducted in solutions of varying acidity, suggested by the E-pH diagrams of the substrate and the alloying elements. The electrochemical results in acid environments (pH 0.5 to 3.0) revealed that passivation of the implanted alloys is pH dependent. The film suffers degradation with Ta dissolution after several polarization cycles. There is no apparent indication of W dissolution according to the polarization characteristics shown by pure W at the same pH. In near neutral chloride solutions, the implanted alloy with higher concentration of the alloying elements showed a marked protective character. A displacement of the pitting potential, Ep, related to aluminium greater than 1.5 V (SCE), was observed.
The role of Ta seems to be twofold, contributing to the enrichment of the film in Ta2C>5 and acting as a reservoir of solute to be oxidized under occluded cell conditions whilst the role of W seems to be in agreement with the solute rich interphase model, that implies local passivation of a pit due to the stability of oxidized solute in localized low pH conditions.
Reduction of Famotidine at a Mercury Electrode using Square-Wave Voltammetry
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by Valentin Mirceski, Blagoja Jordanoski and Sebojka Komorsky-Lovric
43-56
DOI: doi: 10.4152/pea.199801043
Famotidine is an electroactive and a surface-active compound which can be irreversibly reduced at a mercury electrode in moderate acidic media at the potential of about -1.20 V vs Ag/AgCl (KC1 sat.). Square-wave voltammetry of this reaction can be utilised for a quantitative determination of the drug.
