Portulaca grandiflora as new green corrosion inhibitor for mild steel protection in hydrochloric acid: Quantitative, electrochemical, surface and spectroscopic investigations

The inhibition action of the Portulaca grandiflora leaf (PGL) extract against corrosion on N80 carbon steel was tested under 0.5 M HCl acidic conditions at variable temperatures and inhibitor concentrations. The performance behaviour of PGL was evaluated by weight loss and electrochemical techniques including polarisation measurement, open circuit potential, and electrochemical impedance spectroscopy. The analysis results of Fourier transform infrared spectroscopy, ultraviolet spectra, and surface morphology strongly support the corrosion rates results. The obtained outcomes show that the inhibitor can effectively inhibit the corrosion of carbon steel in acidic media with a maximum inhibition efficiency of 95% at high levels of temperature (60 °C) and inhibitor concentration (20 mL/L). The adsorption of PGL on the steel surface followed that according to the Langmuir isotherm model. The heat of adsorption values increased from -17.71 kJ mol-1 to -22.03 kJ mol-1 as the temperature increased from 30 to 60°C suggests a mixed-mode of adsorption on the metal surface.