A study of pomegranate peel extract effect on corrosion inhibition performance on aluminum in HNO3 solution

Green corrosion inhibitors have an important role in reducing the corrosion rate of metals and the effects of toxic chemicals in the environment. In this study, the inhibition effect of pomegranate peel extract (PPE) with concentration of 0.5, 1, 1.5, 2, 2.5 and 3 g/L on the aluminum 1050 alloy corrosion behavior in the nitric acid solution investigates using the weight loss, electrochemical techniques, scanning electron microscope (SEM), atomic force microscope (AFM), contact angle images, gas chromatography-mass spectrometer (GC-MS) analysis, fourier transform Infrared spectroscopy (FTIR) and ultraviolet radiation (UV-IR). And, the (UV-IR), (GC-MS), and FTIR results confirm the presence of many organic compounds (Containing the N, S, and O atoms), which are responsible for inhibitor performance and absorption phenomena. Meanwhile, the electrochemical impedance results (EIS) indicate that the double layer capacity decreases and the corrosion resistance (Corrosion current density (icorr) from 0.128 to 0.009 mA/cm2) increases with the increase of the inhibitor concentration (The inhibition efficiency increased with increasing the inhibitor concentration from % 54.29 to the % 92.58 at (1-3 g/ L). In addition, the corrosion current density decreases with the increase of the inhibitor concentration using the potentiodynamic polarization (PDP) test. However, the corrosion rate enhances with increasing the temperature. From the other hand, quantum chemical (QC) calculation and molecular dynamics (MD) simulation perform to investigate the theory of the adsorption mechanism. According to these studies, the adsorption of PPE on the aluminum 1050 alloy surface is agreement with the langmuir isotherm and as a result it is a mixed-type inhibitor. In final the SEM and AFM results show that the corrosion rate of the aluminum 1050 alloy surface is significantly reduced after the addition of the inhibitor to the corrosive environment. Furthermore, the contact angle image shows that the inhibited aluminum surface has a hydrophobic property in an aqueous solution. And, the QC calculation and MD simulation clarify well the thin layer formation due to the good adsorption of inhibitor (PPE) on the surface of aluminum 1050 alloy in the nitric acid solution, theoretically. It is concluded that PPE will inhibit the surface of aluminum against the corrosion agents in acidic environment and can use as a green inhibitor.