Caesalpinia Crista (Kanchaki) as Green Corrosion Inhibitor for Zinc in Hydrochloric Acid Solutions

A study aims to inspect the surface adsorption of Caesalpinia Crista seed (Kanchaki seed) extract as a developing anti-corrosion additive for zinc in acidizing solutions. The study utilizes various experimental approaches like the mass loss, electrochemical impedance spectroscopy (EIS), and potentio-dynamic polarization (PDP). The study achieves high inhibition efficiencies of 99.4%, 85.0%, and 94.8% in mass loss, potentiodynamic studies, and EIS, respectively at a higher concentration (2.0 g/L) of KSE and a temperature of 303 K. Impedance analyses revealed an increase in charge transfer at the zinc-solution interface upon the addition of the KSE. PDP measurements indicated a significant reduction in corrosion current density when using Kanchaki seed extract (KSE), suggesting its role as a mixed-type corrosion inhibitor. The adsorption of the KSE on the zinc substrate followed the Langmuir isotherm, involving a physical adsorption mechanism. Surface analysis, conducted through contact angle and scanning electron microscopy - energy dispersive X-ray (SEM-EDX) and atomic force microscopy (AFM) measurements, provided additional support for the adsorption of the inhibitor on the zinc substrate. Fourier transform infrared spectroscopy (FT-IR) was utilized to calculate the KSE's functional groups. The experimental outcomes obtained from all the applied approaches show good agreement.