Bili leaf extract: Green corrosion inhibitor for zinc in hydrochloric acid-experimental and theoretical study

Abstract

The primary goal of this study was to examine whether Bili leaf extract (BLE) (Aegle marmelos leaf) could inhibit zinc corrosion in an acidic environment, specifically in 0.05–0.10 M HCl solutions. The corrosion rate was examined using PDP (Potentiodynamic Polarization), EIS (Electrochemical Impedance Spectroscopy), and weight loss techniques. The research attains notable inhibition efficiencies of 99.0 %, 83.4 %, and 78.95 % in weight loss, PDP, and EIS respectively, at a concentration of 2.0 g/L BLE and a temperature of 303 K. The influence of temperature (ranging from 303 to 333 K) on the corrosion behaviour was examined upon the addition of BLE. As the concentration of BLE increased, the corrosion rate(CR) of Zn decreased, and a similar reduction was observed with decreasing temperature. Adsorption of BLE onto the metal surface followed by Langmuir and Freundlich adsorption isotherm models. The activation parameters of BLE and its negative Gibbs free energy indicate spontaneous adsorption rates. Tafel polarization measurements showed that BLE acts as a mixed-type corrosion inhibitor, meaning it influences anodic and cathodic reactions. FT-IR spectroscopy is employed to determine the functional groups of BLE. Atomic Force Microscopy(AFM)/Energy Dispersive X-ray (EDX)/Scanning Electron Microscopy (SEM) images of the zinc surface verified a significant reduction in surface inhomogeneities when BLE was present. The quantum parameters obtained through DFT(Density Functional Theory)/MD (Molecular Dynamics) demonstrated excellent agreement with the experimental findings.