Caesalpinia crista seed is used as an eco-friendly inhibitor to prevent the corrosion of aluminium in hydrochloric acid solutions

Abstract

This investigation delves into the inhibitory impact of Caesalpinia crista (Kanchaki) seed extract (CCE) on the corrosion of aluminium alloy (AA6061) at temperatures varying between 303 and 333K, employing Potentiodynamic Polarisation (PDP), Electrochemical Impedance Spectroscopy (EIS), and weight loss methodologies. Findings demonstrate that CCE extract effectively safeguards Al against corrosion, with efficacy increasing at higher concentrations. The observed inhibitory action exhibits a cathodic-type behavior across all concentrations and temperatures, aligning well with Langmuir isotherm. Notably, the highest level of inhibitory efficiency, reaching 96.87 ​%, is attained at a concentration of 2.0 ​g/L and a temperature of 303 ​K for 3 hours. Consistency is observed between the results obtained through EIS and PDP. A plausible mechanism for preventing corrosion in Al alloy is proposed. Surface analysis techniques, such as Atomic Force Microscopy (AFM) and Scanning Electron Microscopy/Energy Dispersive X-ray analysis (SEM/EDX), validate the adsorption of the inhibitor onto Al alloy surfaces. Morphological examinations corroborate electrochemical findings, confirming protection against uniform corrosion in HCl solutions. Additional analyses involve the computation of activation energy and thermodynamic parameters, with a thorough discussion of the results.