| Abstract: |
The effect of addition of various concentrations of pyridine, nicotinic acid and 8-hydroxyquinoline on the corrosion of Delta-steel electrode in 1M and 3M H3PO4 has been investigated using weight loss and gasometric techniques. The inhibition effect was sInhibitive performance of pyridine, nicotinic acid and 8-hydroxy-quinoline on corrosion of Delta steel electrode in 0.1 M H3PO4 was studied using electrochemical methods. The efficiency of the used inhibitors was calculated using Tafel extrapolation methoThe electrochemical behaviour of Delta-steel electrode has been studied in 0.05 and 0.5M Na2HPO4 solutions using the galvanostatic method (cyclic anodic and cathodic polarization). The data of the anodic polarization process indicate presencce of three arAlso, the galvanostatic passivation of the same elctrode in different concentrations of Na2HPO4 can be satisfactorily represented by the relation:log t = A – n log jwhere j is the polarizing current density, t is the time elapsed before O2 evolution, and A and n are constants.The electrochemical behaviour of Delta-steel electrode in Na2HPO4 solutions containing various concentrations of Cl-, Br-, S--, ClO3- and ClO4- as aggressive anions has been studied. The data show that lower concentrations of these aggressive anions have The addition of increasing concentrations of CrO42-, MoO42-, HPO42- and CO32- shifts the potential of oxygen evolution towards more positive values and the polarization curves recall those reported in aggressive anion-free solution indicating pitting corrCyclic voltammetric technique is used, also, to study the electrochemical behaviour of Delta-steel electrode in phosphate solutions. The data show that, the shape of the voltammograms depends on the concentration of H2PO4– ions, the starting potential andlog j = α + β log Cwhere α and β are constants. A corelation was made between the anodic oxidation processes and their corresponding cathodic ones.The anodic behaviour of Delta-steel electrode in H2PO4– containing various concentraions of Br-, Cl-, ClO4-, ClO3- and SCN- as pitting anions is also studied by the potentiodynamic technique. Also, the presence of lower concentrations of these anions has Cl- > Br- > SCN- > ClO4- > ClO3-.Addition of increasing concentrations of glucose, lactose, and soluble starch causes a decrease in the current density along the active region and also a shift in the breakdown potential towards noble direction. The efficiencies of these compounds as pitt
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