Sage extract as an inhibitor of steel and copper corrosion

Protection of steel and copper from corrosion was caried out by processing corrosive environment using different concentrations of sage extract (0.5 g/dm3, 1 g/dm3 and 1.5 g/ dm3) as a green inhibitor in 3% NaCl and 4% HCl solutions. The rates of steel and copper corrosion in the solutions prepared were measured using gravimetric analysis and electrochemical methods (the Tafel extrapolation method and electrochemical impedance spectroscopy). The highest level of steel protection (z= 97.5%) in the 3% NaCl solution occurs with the concentartion of sage of 1.5 g/dm3 for a six-hour time interval. Sage concentrations of 1.0 g/dm3 and 1.5 g/dm3 in the 3% NaCl solution exhibit a very good inhibitory action, since the average protction factors are 78.5% and 95.3% respectively. These results prove that sage can be used as a potential inhibitor of steel corrosion in the 3% NaCl solutions. Corrosion protection for steel in the 4% HCl is considerably lower, not more than 64.5%, which means that sage can only be used as a green inhibitor for a shorter period of time. The highest level of copper protection (z=60,04%) in the 3% NaCl is for the sage concentration of 1 g/dm3, whereas for the concentration of 1.5 g/dm3 it is 53% for a six-hour time interval. However, the same solutions for the time intervals of 4 and 24 h have a catalytic action in the process of copper corrosion, so it is not recommended to use sage extract as a green inhibitor for copper in the 3% NaCl. The highest protection factor achieved in the 4% HCl is 59.96% in the solution which contains 1 g/dm3 of sage extract. This value is not sufficent to recommend sage extract as an inhibitor of copper corrosion in the 4% HCl. The results obtained from electrochemical measurements confirm the results obtained by gravimetric analysis, which makes them, therefore, recommendable as fast and relibale methods in corrosion testing.