Environmentally conscience corrosion inhibitors for mild steel in corrosive hydrochloric acid solution by Uncaria Cordata extract: experimental and theoretical studies

Abstract

The Uncaria Cordata as corrosion inhibitors for mild steel (MS) in a 1.0 M hydrochloric acid (HCl) solution. The EIS, polarization, and LPR measurements were used as experimental measurements to confirm the anti-corrosion performances of the Uncaria Cordata at room temperature. The corrosion inhibitors, even at a low dosage range, achieved inhibition efficiencies to a maximum of 97.0% for 400 ppm of Uncaria Cordata. Surface morphology via AFM and SEM/EDX was carried out to validate the presence of protected film and an optimum concentration of each extract above the metal’s surface in the corrosive acidic solution. The ΔG^o_ads value − 19.70 kJ/mol proved a spontaneous merge of physical and chemical adsorption by the extract compounds at the interface of MS and the HCl solution. DFT was governed to accommodate the elevated inhibition efficiency upshot obtained by the electrochemical tests and recommend a synergy mechanism for most of the adsorbed active compounds in Uncaria Cordata inhibitors with the MS surface. Monte Carlo simulation indicates three active compounds, namely 1, 2, and 8, found to have parallel adsorption on MS. This encourages the highest surface coverage and shields the MS surface from the intrusion of corrosive agents.

Keywords:

• Uncaria Cordata
• corrosion inhibitor
• mild steel
• DFT
• Monte Carlo

Acknowledgement

This work was supported by the Universiti Teknologi MARA (UiTM) under Grant 100-RMC 5/3/SRP (094/2021) and 600-RMC/MyRA 5/3/LESTARI (011/2020).

Author contributions

Nor Affanizam Othman: Visualization, Formal analysis, Methodology, Software, Data Curation, Writing - Original Draft. Ab Malik Marwan Ali: Resources. Noor Syafiqah Samsi: Methodology, Investigation, Data Curation. Fatimah Salim: Resources. Dedikarni Panuh: Funding acquisition. Muhamad Kamil Yaakob: Supervision, Software, Validation. Zaidi Embong: Supervision, Writing- Reviewing and Editing, Ahmad Shalabi Md Sauri: Resources. Nik Norziehana Che Isa: Funding acquisition. Nor Zakiah Nor Hashim: Supervision, Conceptualization, Validation, Visualization, Project administration.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.