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Interferência do Cr (VI) nas Determinações Voltamétricas de Metais Pesados
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by António C. Barbosa, Taís A. Pitta G. Cotta
343-346
DOI: doi: 10.4152/pea.198703343
The Use of Ion Selective Electrode in the Study of Complex Formation. Reactions of Silver Ion with Amino and Carboxylic Group Ligands
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by J. M. Caridade Costa, J. Simões Redinha
347-350
DOI: doi: 10.4152/pea.198703347
Water Determination in Organic Solvents by Oscillometry
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by M. Luíza P. Leitão, Felisbela S. Costa, J. Simões Redinha
351-355
DOI: doi: 10.4152/pea.198703351
Pressure and Temperature Effects on the Walden Product of Two Tetra-Alkyl Ammonium Salts in Different Solvents
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by César A. N. Viana, António T. Calado, Henrique Vicente
357-359
DOI: doi: 10.4152/pea.198703357
Peculiar Behaviour of Ionogenic Aqueous Solutions Around 4°C.
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by C. A. N. Viana, M. M. G. S. Rocha
361-362
DOI: doi: 10.4152/pea.198703361
Cementation of Copper on Packed Beds of Aluminium Pellets
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by A. A. Wragg, C. R. Dresner
363-366
DOI: doi: 10.4152/pea.198703363
The Pd-Gate Misfet as an Electrochemical Sensor for Corrosion Processes
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by C. A. C. Sequeira, A. M. G. Pacheco, M. G. I. B. Teixeira
367-369
DOI: doi: 10.4152/pea.198703367
The Pitting Corrosion of Mild Steel in Chloride Containing Solutions
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by C. M. Rangel, M. H. Simplício, M. G. S. Ferreira
371-374
DOI: doi: 10.4152/pea.198703371
Influence of Oxygen Diffusion on the Mechanism of Corrosion Processes under Thin Electrolyte Films
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by M. Júlia Justo, Mário G. S. Ferreira, M. Elisabete Almeida
375-378
DOI: doi: 10.4152/pea.198703375
Electrochemical Preparation of a Copper Tool--Electrode Utilized in Electric - Discharge Machining
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by P. Molera, E. Julve
379-382
DOI: doi: 10.4152/pea.198703379
Mesures Électrochimiques pour Évaluation des Inhibiteurs de la Corrosion
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by Juan de Damborenca, A. J. Vazquez
383-386
DOI: doi: 10.4152/pea.198703383
Solar Selective Black Ni-Cd Alloy Coatings for Electrodeposition
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by Julio P. Roda, Fernando S. Fernandez, Francisco T. Espinosa
389-390
DOI: doi: 10.4152/pea.198703389
Polarization Curves of the Atmospheric Corrosion Phenomena
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by J. A. González, E. Otero
391-394
DOI: doi: 10.4152/pea.198703391
by J. E. Simões
395-408
DOI: doi: 10.4152/pea.198703395
Influence of the Surface Structure of Metal Electrodes on the Double Layer Parameters and Reaction Kinetics
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by A. Hamelin
77-101
DOI: doi: 10.4152/pea.198702077
Membrane Electrodes of Herbicidal and Pharmaceutical Interest
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by F. N. Assubaie, G. J. Moody, R. K. Owusu et al.
103-124
DOI: doi:10.4152/pea.198702103
Mechanism of Reduction of Ni(II)-Alcoholamine Complexes on the Dropping Mercury Electrode
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by F. Rey, J.M. Antelo, F. Arce et al.
125-133
DOI: doi:10.4152/pea.198702125
The Polarographie characteristics of the NKI I) ion in presence of the four aminoalcohols monoethanolamine, N-methylethanolamine, N-ethylethanolamine and N,N-dimethylethanolamine are reported. In general, half-wave potentials for the complexes are more positive than for the aquo-ion, and shift towards more negative values as the concentration of ligand increases. Transfer coefficients, <*c, electrode reactions rates and activation energies were determined for the reduction of the complexes. Differences between the reduction mechanism of the various NKI I)- aminoalcohol complexes are pointed out.
Voltammetric Study with a Glassy Carbon Electrode of the Pesticides Fenthion and Fenitrothion
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by J. H. Mendez, R. C. Martinez, F. B. Dominguez et al.
135-146
DOI: doi 10.4152/pea.198702135
The voltammetric behaviour (d.c. and d.p.v.) of the pesticides Fenthion and Fenitrothion on a glassy carbon electrode is described. Fenthion is oxidized at + i.20 V (vs Ag/AgCl) but Fenitrothion is reduced at - 0.60 V. Both electroanalytical responses can be used for the determination of the two pesticides with detection limits of 1.36 and 0.46 uM, respectively.
Kalousek Polarographic Study of Co (II) in Britton-Robinson Media
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by M.A. Nunez Flores, C. Sanz, C. Monleõn et al.
5-14
DOI: doi:10.4152/pea.198701005
The polarographic behaviour of Co(II) in Britton-Robinson media is studied by Kalousek's polarographic methods. The experimental contribution at the study of the reduction of Co(II) and re-oxidation of Co(0), mechanism which takes place on the d.m.e.is discussed. The na^ and na^ values correspond to processes where monoelectronic transfer steps are coupled with chemical-physical steps.
Possibilities of Voltammetric Methods for Speciation in the Presence of Particles
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by Maria de Lurdes Simões Gonçalves
15-32
DOI: doi:10.4152/pea.198701015
Differential pulse polarography and anodic stripping voltammetry can be used directly in suspensions without pre-filtration; heavy metals like copper(II) and lead(II) adsorbed on hydrous oxides such as silica and ct-goethite are not being released during the time scale of the techniques and are thus not sensed by these techniques. In samples with colloids and organics such as EDTA and NTA in the presence of heavy metals, when the complexes are non-labile but electro-chemically reducible at a more negative potential, one can determine the ligand concentration and the binding capacity of the colloid from the voltammetric measurements of individual batches with different amounts of cations like copper(II) and lead(II).
From the differential pulse measurements of solutions with heavy metals and the organic ligands EDTA and NTA, it is possible to know directly the amount of metal bound to each one of the ligands and the free cation. This can also be determined by anodic stripping voltammetry at different deposition potentials.
