Abstract
The corrosion inhibition of mild carbon steels in an acidic environment by using ampicillin (AMP) has been evaluated based on experimental and quantum chemistry techniques. The experimental results indicate that the inhibition efficiency goes up at higher AMP concentration. The highest inhibition efficiency reaches 84.9% for polarization measurement and 90.1% for electrochemical impedance spectroscopy with the inhibitor of concentration 100 ppm at 298 K. The surface characteristics (SEM) also reconfirm the steel corrosion inhibition ability of AMP. Some important chemical factors such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), ΔEL−H (energy gap), and Fukui functions were calculated based on the optimized configuration of AMP at the theoretical level of B3LYP/6-31+G(d,p). Moreover, Monte Carlo and molecular dynamics simulations were used to analyze the absorption behavior of inhibitor on the surface of Fe(110), which supplies the mechanism of inhibition corrosion processes. The obtained results showed that AMP is considered to be a potential corrosion inhibitor for mild steel in 1M HCl medium. Moreover, the protonated state of AMP plays an important role in the protection of Fe surface against the corrosive process.
Highlights
Corrosion of metals is a key problem in industrial processes that has fascinated a large number of studies [1,2,3,4]
After the specimen was immersed in the 1M HCl solution for 60 minutes, potentiodynamic polarization investigations were performed with a scanning rate of 1 mV/s in the potential range of −600 mV to −300 mV
Mild steel samples were prepared and immersed in 1M HCl with the AMP concentrations of 0, 20, 40, 60, 80, and 100 ppm in 6 hours. ereafter, the specimens were washed with distilled water, degreased with acetone, wiped with a clean towel paper, and airdried. e surfaces of specimens were observed by using an EVO-ZEISS scanning electron microscope (SEM) at the Analysis Centre for Import Export Products, Danang Branch (Vietnam)
Summary
Corrosion of metals is a key problem in industrial processes that has fascinated a large number of studies [1,2,3,4]. E advantage of many synthetic organic compounds is that they are cheap and possess efficient anticorrosive activity, but their disadvantage is that they are harmful to humans and pollute the environment To remedy this situation, green corrosion inhibitors originated from natural products and drug compounds are preferred because of their eco-friendly and nontoxic nature [11]. The antibiotic residues may be released into the environment through wastewater effluent, medical waste, etc., which are the causes of environmental pollution These compounds have heteroatoms in their structures, as mentioned in the previous paragraph, which can get effectively absorbed on the metal surface and protect it from corrosion [2, 12, 13]. Three computational methods (DFT, MC, and MD) were used to provide vital insights into the inhibition process at the molecular level
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