An-Najah Staff

The assignment of metal complexes to various regimes on the basis of their dissociation kinetics is one type of metal speciation study. The most common scheme, which involves column ion-exchange as a means of separating free metal ions and metals in the form of highly labile complexes from other forms of metals in the sample, is demonstrated to categorize incorrectly stable, charged complexes such as iron(II) and nickel(II) o-phenanthroline as labile. Donnan dialysis is an alternative ion-exchange method for metal speciation studies. Data are provided which demonstrate that the above complexes are correctly assigned by the Donnan dialysis method. The relative labilities of ethylenediamine and triethylenetetramine complexes of iron (II) and nickel (II) are also correctly determined by Donnan dialysis.

A brief review is given to study inhibitive action of Poly (4-vinylpyridine) – Graft - Bromodecane (P4VPBrD) at three degrees of quaternisation (25%, 45% and 60 %) on the corrosion behaviour of pure iron was investigated in desaerated molar sulphuric acid solution using weight loss measurements, potentiodynamic polarisation, and impedance spectroscopy (EIS) methods at free corrosion potential. A polarisation measurement shows also that the compound acts as a mixed-type inhibitor and was adsorbed on the iron surface according to the Langmuir adsorption isotherm model. The parameters, which characterise the corrosion behaviour, can be determined from plots and diagrams of Nyquist. There inhibition efficiency (E %) increases with the all inhibitors concentration. Trends in the increase of charge transfer resistance and decrease of capacitance values also shows the molecular adsorption on the metal surface. The temperature effect on the corrosion, behaviour iron metal in 1M H2SO4 without and with inhibitor at 510 -5 M was studied at the temperature range from 298 to 338 K, the associated activation energy have been determined and proved that the adsorption is a spontaneous process.