Alkaloids from methanolic extract of Berberis asiatica as a potential corrosion inhibitor for active metal

The growing demand of inhibitors for the prevention of corrosion leads to the search of sustainable and eco-friendly inhibitors. This study deals with the corrosion protection of mild steel using alkaloid extract of B erberis asiatica stem in 1 M H 2 SO 4 . The Ultraviolet–Visible (UV–Vis) and Fourier transform infrared (FTIR) spectroscopy established the presence of compounds containing nitrogen and oxygen. Strong coordination between the inhibitor molecules and the metal surfaces has been established by the clear identification of N1s and O1s peaks in X-ray photoelectron spectroscopy (XPS), corresponding to Fe N and Fe O bonds, respectively. Gravimetric and electrochemical methods were used to study IE. The results showed that IE increased with increasing inhibitor concentration, achieving 93.34 % IE at a concentration of 10 ppm. Inhibition efficiency decreases with increasing immersion duration or temperature. The inhibiting mechanism is believed to result from the adsorption of the alkaloid molecules at the MS-solution interface, following Langmuir-type behavior and indicating a single-layer (monolayer) adsorption process. The standard free energy of adsorption, ΔG° = −41.20 kJ mol −1 , and activation energy (Ea) up to 97.94 kJ mol −1 were determined. Thermodynamic calculations confirmed that the adsorption is spontaneous and endothermic. The kinetic calculation confirmed that charge-transfer reactions are the rate-controlling step in corrosion. Field emission scanning electron microscopy (FE-SEM) and Atomic force microscopy (AFM) revealed smoother surfaces in the inhibited samples. This clearly reflects that Berberis asiatica's alkaloids act as a promising, environmentally benign, and excellent green corrosion inhibitor for mild steel in acidic environments. Separation of DCM soluble alkaloids from methanolic extract of Berberis asiatica stem, characterization of the extract, and study of its corrosion inhibition efficiency.