Abstract
The inhibitive effect of mebendazole (MBZ) on the corrosion of low-carbon steel in H2SO4 was investigated by gravimetric and electrochemical techniques as well as examination of specimens in the scanning electron microscope with attached energy dispersive X-ray spectrometer (EDS). From gravimetric analysis, the highest inhibition efficiency of about 96.6% was obtained for 1.0 g of inhibitor in H2SO4 solution at 24 h, while with longer exposure times of between 72 to 120 h, the efficiencies averaged between 92 and 95%. Tafel extrapolations from the polarization curves showed that 1.0 g MBZ gave a maximum inhibition efficiency of approximately 99% for the investigation conducted at 30°C, whereas 1.5 g of MBZ gave a maximum inhibition efficiency of about 85% at 60°C. Inhibition efficiency increased with increasing concentrations of MBZ and decreased at elevated temperatures. The inhibitive action was attributed to physical adsorption of MBZ species on the mild steel surface which followed the Langmuir adsorption isotherm. MBZ performed as a mixed-type inhibitor on mild steel in dilute H2SO4.
Highlights
In order to mitigate corrosion, an effective and flexible means is through the use of corrosion inhibitors [1, 2]
Electrochemical Measurements. e polarization experiments were carried out using an Autolab potentiostat/ galvanostat VersaSTAT 4 Electrochemical System controlled from a computer by a Universal Serial Bus (USB) interface using the Versa Studio electrochemistry software package
Gravimetric Measurements. e results of gravimetric measurement in terms of weight loss (WL), corrosion rate (CR), percentage inhibition efficiency (η), and surface coverage (Φ) are displayed in Table 1 while the graphical representations for the various parameters are presented in Figures 1–4. e plot of weight loss against exposure time for mild steel with and without varying concentrations of MBZ (Figure 1) showed significant decrease in weight loss upon the introduction of MBZ into the corrosive media. e rate at which weight loss occurred was reduced with increases in the concentration of the inhibitor (Figure 2)
Summary
In order to mitigate corrosion, an effective and flexible means is through the use of corrosion inhibitors [1, 2]. Corrosion inhibitors have found major use in closed systems with good circulation and controlled inhibitor concentrations, which may include cooling water recirculation systems, oil production and refining, industrial acid cleaning, and acid pickling of steel components. Inorganic inhibitors such as chromates and zinc salts have suffered major setbacks in their usage as a result of toxicity and have largely been replaced with organic inhibitors [16, 17]. Benzimidazole and its derivatives have excellent pharmacological properties such as anti-bacterial, anti-fungal, anti-cancer, anthelminthic, etc They display planar structures with anchoring sites at sp hybridized nitrogen carrying lone pairs of electrons coupled with aromatic rings. Mebendazole is a synthetic benzimidazole derivative which may be nontoxic and biodegradable and has been employed in therapeutic treatments as anthelmintic drug that has the molecular formula of C16H13N3O3 with a molecular weight of 295.3 g/mol
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