Corrosion Inhibition of Aluminium by Rice Straw Extract in 2 M Hydrochloric Acid Solution

Abstract

In our research, the rice straw extract was used as an eco-friendly green inhibitor to prevent Al dissolution in 2 M of HCl. Mass loss, electrochemical [potentiodynamic (PP), electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM)] techniques and surface checks were used to illustrate the importance of this extract to the corrosion inhibition process of Al in 2 M HCl. From mass loss tests, one can find that with an increased concentration of rice straw extract up to 300 µM, the inhibition efficacy reached to 96.8% after 3 h at 25 °C. Polarization curves showed that rice straw extract is a mixed-type inhibitor that retards the Al dissolution and hydrogen evolution reactions. From the EIS tests, the reduction of the double layer by raising the concentration of rice straw extract was observed, and on the other hand, the charge transfer resistance is increased. The inhibition efficacy (%I) of Al occurs by the adsorption process, and Al is subject to the adsorption following both Flory–Huggins and Langmuir isotherms. Thermodynamic data and XPS analysis indicated that the adsorption mechanism of the extract on Al surface in 2 M HCl solution is mainly controlled by chemisorption and physisorption processes. From these isotherms, the adsorption parameters were computed. The effect of temperature was applied, and the activated parameters were calculated and discussed. Results gained from all techniques were in reasonable agreement.