The feasibility of using Eriobotrya japonica Lindl (EJL) extract as a green inhibitor towards mild steel corrosion retardation in 1 M HCl solution was evaluated through integrated experimental and computational perspective. By utilizing electrochemical and surface analyses benefits, including EIS, potentiodynamic polarization, SEM, AFM and contact angle test, the protection function of EJL extract was studied. In addition, the EJL extract itself was examined by means of FT-IR and UV–Vis analysis. EIS results revealed the increase in mild steel corrosion resistance in the presence of EJL extract by increasing the extract concentration. The highest resistance was achieved at 800 ppm concentration. A mixed type behavior of EJL extract with dominant anodic dissolution reduction was proved by DC polarization. The lowest current density was obtained at 800 ppm concentration. SEM and AFM images indicated the protective layer growth on steel surface having intact surface morphology and more homogeneity in the presence of inhibitor. Contact angle test results confirmed the steel surface wettability enhancement by addition of EJL extract. The presence of functional groups, which make the inhibitors molecule adsorption possible, was verified by FT-IR and UV–Vis tests results. Furthermore, the computational methods (i.e., quantum mechanics and molecular simulations) evidenced the binding of EJL extract compounds onto steel substrate, affirming the inhibition action of EJL extract.

Introduction

Many industrial processes on the metals such as cleaning, pickling, descaling and etc. are conducted by taking advantages of acidic solutions [1–۴]. This prevalent method provides severe corrosion attack due to the susceptibility of metals and alloys towards aggressive acidic media, which led to property lost. Employment of organic inhibitors for the acidic solution has been widely considered as a practical protecting approach to diminish the corrosion occurrence [5–۹]. The inhibitive behavior of plants extract has been extensively evaluated by many authors and also by this group. Inhibitive performance of Aloe extract as a green corrosion inhibitor in the H2SO4 solution was proved by utilizing EIS and DC polarization methods by means of which the highest inhibition efficiency was determined about 97% at 30% v/v [10]. In another work, the inhibition function of Morus Alba Pendula leave extract (MAPLE) toward carbon steel corrosion mitigation in 1 M HCl solution was examined and by taking advantage of electrochemical analysis 0.4 g/L Maple yielded 93% inhibition efficiency [11]. Satapathy et al. [12] showed that the protection of mild steel in 1 M HCl was strengthened by increasing the concentration of Justicia Gendarussa plant extract (JGPE), which acted as a mixed-type inhibitor with concern to the polarization test results. Ji et al. [13] announced the raw banana peel extract as a perfect inhibitor with a 92% efficiency for protection of mild steel in HCl solution.