Methanolic extract of curcum plant as a green corrosion inhibitor for steel in Nacl polluted solutions

The effect of curcum plant extract on the corrosion of steel used in sanitation treatment plants in 3.5% NaCl and 16 ppm Na2S was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The results obtained showed that the curcum extract is a good inhibitor for steel in NaCl polluted solutions Potentiodynamic polarization curves indicated that the curcum extract behaves as mixed-type inhibitor with predominant cathodic effect. EIS measurements showed that the dissolution process of steel occurs under activation control and the inhibition is due to the adsorption of the extract on the metal surface. Thermodynamic consideration reveals that adsorption of curcum extract on steel surface is spontaneous and occurred according to Temkin adsorption isotherm. Physical adsorption mechanism has also been proposed for the adsorption of the inhibitor. The biological study of the extract on Escherichia coli activity shows that this extract is safety for applying in sanitation plants