Abstract
The inhibitory effect of 1-hexadecyl-2,3-dimethylimidazole hexafluorophosphate ([C(16)DMIM](+)[PF(6)](-)) on carbon steel was investigated in both 1 M hydrochloric acid (HCl) and 1 M sulfuric acid (H(2)SO(4)) solutions. The thermodynamic and kinetic corrosion parameters were calculated through weight loss and electrochemical measurements. The results showed that the addition of 0.05 mmol/L [C(16)DMIM](+)[PF(6)](-) resulted in an inhibition efficiency of 98.28% and 80.10% in 1 M HCl and 1 M H(2)SO(4) at 363 K, respectively. The adsorption of [C(16)DMIM](+)[PF(6)](-) obeyed the Langmuir adsorption isotherm, presenting a competition between physical and chemical interactions in the H(2)SO(4) solution, while it was chemisorption in the HCl solution. Surface analysis techniques (SEM) demonstrated that the inhibitor could form a protective film on the carbon steel surface. Molecular dynamics simulations were utilized to determine the interaction of the [C(16)DMIM](+)[PF(6)](-) molecule with H(2)SO(4) and HCl on the Fe(110) surface, and the adsorption energies of the inhibitor in both acid solutions were determined. The simulation results were in close agreement with the experimental results, and due to the adsorption energy in the HCl solution, the inhibition efficiency of the HCl solution was superior to that in the H(2)SO(4) solution. These results demonstrate that [C(16)DMIM](+)[PF(6)](-) can be a sustainable, less hazardous corrosion inhibitor for carbon steel in acid solutions.