Zataria multiflora essential oil as a green corrosion inhibitor for copper in HCl electrolyte

This study explores Zataria multiflora essential oil (ZmEO) as a green corrosion inhibitor for copper in acidic solution. The essential oil was extracted through hydrodistillation and profiled by gas chromatography-mass spectrometry (GC-MS), indicating major constituents including linalool (63.14%), carvacrol (23.50%), and β-caryophyllene (2.54%). Corrosion inhibition efficacy was determined through weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) at concentrations of 25-100 mg/L. Results depicted concentration-dependent inhibition, with maximum efficacy of 80.00% (gravimetric), 84.15% (PDP), and 82.9% (EIS) at 100 mg/L. Surface analysis via atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM) corroborated smoother morphologies and decreased roughness (R q decreased from 265 nm to 74 nm) with inhibitor addition. Adsorption followed the Langmuir isotherm (R 2 > 0.994), with ΔG ads values (-27.42 to -28.60 kJ/mol) indicating spontaneous mixed physisorption-chemisorption. Density functional theory (DFT) calculations on key components supported their reactivity and adsorption via electron donation to copper d-orbitals. Immersion time studies showed sustained efficiency (>91%) up to 24 hours. ZmEO emerges as a viable green replacement for artificial inhibitors, affording effective protection through a stable adsorptive film.