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Potentiodynamic polarization studies were carried out to get the electrochemical kinetics of the cathodic and anodic reactions occur during the corrosion inhibition process.The Tafel polarization curve for iron in 1M and 0.5M without and with various concentrations of inhibitor is given in Fig(10) and Fig(11). The electrochemical parameters viz., corrosion potential (Ecorr), corrosion current density (Icorr), and Tafel slopes (ba and bc) for the corrosion of iron in 1M HCl and 0.5M HCl containing various concentrations of pOAPOT are given in the table(2).
The Tafel curves shows that the Ecorr value of iron in 1M HCl was found to be -488mV without the addition of inhibitors and it shows a potential shift from -486.93 mV to 465.06 mV versus SCE in the corrosion potential (Ecorr), relative to the value of ion without inhibitors. The positive shift in (Ecorr) specifies the corrosion performance of iron in presence of inhibitor in acid medium. Ecorr value for Iron in 0.5M HCl without the inhibitor is 507.32 mV and it seems that the potential is shifted from 513.51 mV to 508.77 mV for the addition of copolymer pOAPOT 50 to 200 ppm. The corrosion current density for inhibitor-free 1M HCl is 2492.6 A/cm2 and it decreases from 706.1 A/cm2 to 472.7 A/cm2 on increasing the concentration of pOAPOT copolymer to yield 81.03%. In 0.5M HCl the Icorr value is 1937 A/Cm2 (inhibitor-free solution) and it decreases to 643.1 A/Cm2 for the 200ppm inhibitor. The Ecorr values are below 85mV indicates that the polymer behaves as a mixed type of indicator.21 Bode plot for the Blank and copolymers for iron are shown in Fig(6) and Fig(8).