Corrosion inhibition of mild steel by Nettle (Urtica dioica L.) extract: polarization, EIS, AFM, SEM and EDS studies

Inhibitory action of Nettle (Urtica dioica L.) extract was investigated in hydrochloric acid solution through electrochemical (polarization, EIS) and surface analysis (optical microscopy/AFM/SEM/EDS) techniques. Effect of inhibitor concentration and temperature were evaluated. Thermodynamic parameters have been calculated and adsorption studies have been investigated. The electrochemical studies showed that NE inhibitor retards both cathodic and anodic processes through the inhibitor adsorption on the metal surface and blocking the active corrosion sites. A good fit to Langmuir adsorption isotherm was obtained between surface coverage degree and inhibitor concentration. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the microstructure and the nature of the metal surface. SEM and AFM images and energy dispersion spectrometer analysis for mild steel specimens in the absence and presence of the NE inhibitor confirmed the protective layer formation on the metal surface and proved the results obtained by the electrochemical experiments. Inhibition efficiency up to 92.24% has been achieved in 1 M acid solution containing 0.3 g/l inhibitor at 40 °C.