Benzyl triphenyl phosphonium bromide as a corrosion inhibitor: A multifaceted study on aluminium protection in acidic environment

• BTPB exhibits remarkable corrosion inhibition performance, achieving efficiencies of up to 98.51 %, even at elevated temperatures (up to 328 K). • Tafel polarization studies show BTPB influences both anodic and cathodic reactions, classifying it as a mixed-type inhibitor. • The adsorption of BTPB onto the aluminum surface best fits the Langmuir isotherm, suggesting a monolayer adsorption process. • EIS results confirm increased charge transfer resistance (R ct ) with increasing BTPB concentration, further indicating improved corrosion protection. • DFT calculations demonstrate BTPB's electron-donating and accepting capabilities, explaining its interaction with the aluminum surface and its effectiveness as a corrosion inhibitor. Corrosion, a globally recognized issue, leads to reduced efficiency, significant economic losses, and the depletion of natural resources. Ionic liquids, particularly phosphonium-based compounds, are considered environmentally benign and sustainable alternatives. In this study, the use of Benzyl Triphenyl Phosphonium Bromide (BTPB) as a novel and efficient corrosion inhibitor for 6106 aluminum alloy in hydrochloric acid was investigated through electrochemical and surface analysis techniques. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and weight loss measurements were employed to evaluate its inhibition performance. BTPB exhibited an exceptional maximum inhibition efficiency of 95.95 % at 308 K, with efficiency improving with increasing concentration. Adsorption studies indicated that BTPB follows the Langmuir adsorption isotherm, while thermodynamic analysis provided deeper insights into the adsorption mechanism. Furthermore, surface characterization by scanning electron microscopy (SEM), atomic force microscopy (AFM), and density functional theory (DFT) calculations supported the experimental findings, confirming strong interactions between BTPB molecules and the aluminum surface. The outstanding inhibition efficiency, combined with the green and environmentally friendly nature of BTPB, underscores its potential as an advanced corrosion inhibitor for aluminum alloys in acidic environments.