Effect of substitution on corrosion inhibition properties of 4-(substituted fluoro, chloro, and amino) Benzophenone derivatives on mild steel in acidic medium: A combined Electrochemical, surface characterization and theoretical approach

Background

: In this study, three mono-substituted Benzophenone (BP) derivatives, 4-Fluorobenzophenone (4-F.BP), 4-Chlorobenzophenone (4-C.BP), and 4-Aminobenzophenone (4-A.BP) were investigated using a combined electrochemical, surface characterization and theoretical approach.

Methods

: In experiment, the effectiveness of 4-F.BP, 4-C.BP, and 4-A.BP in inhibiting mild steel corrosion in a 1 N HCl solution were investigated using gravimetric measurements at several temperatures (303–333 K), electrochemical measurements (Potentiodynamic Polarization (PDP), and Electrochemical Impedance Spectroscopy (EIS)), UV–visible analysis, Surface morphology test (SEM and EDAX analysis, AFM analysis, water contact angle measurement, XPS analysis) as well as theoretical studies.

Significant findings

: Increase in the inhibitor concentrations (160, 200, 240 and 280 ppm) exhibited a maximum percentage of inhibition efficiency (IE %) of 83.75 %, 88.75 %, and 93.75 % for 280 ppm of 4-F.BP, 4-C.BP, and 4-A.BP respectively at 303 K. However, with increase in the temperature from 303 to 333 K, IE % furthermore reduced to 52.41 %, 57.24 %, and 66.20 % at 333 K. The potentiodynamic polarization plots revealed that all molecules acted as mixed-type corrosion inhibitors and had an exceptional ability to inhibit the anodic reaction. Moreover, Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM), and Contact angle measurement (CAM) confirms the formation of protective layer on the metal surface by the chosen inhibitors. The X-ray Photoelectron Spectroscopy (XPS) data confirms the bonding interaction between the functional groups and the metal surface. Furthermore, Density Functional Theory (DFT) calculation and Molecular Dynamics simulations (MD) were carried out to understand inhibition's molecular/atomic mechanisms. In summary, the suggested benzophenone derivatives are effective and economical anticorrosion agents for mild steel surfaces exposed to aggressive environments.