DFT, Monte Carlo, molecular dynamics, electrochemical, and weight loss study on corrosion inhibition of aluminum by trimethoprim and sulfamethoxazole in HCl

The mitigation of aluminum corrosion in HCl is crucial for economic, safety, and environmental considerations. The influence of Trimethoprim-Sulfamethoxazole (TMP-SMX) on the corrosion of aluminum in 1 M HCl was investigated through both electrochemical and computational methodologies. A notable difference in the open circuit potential values between the blank HCl and the inhibited system was recorded, indicating that TMP-SMX affects the electrochemical behavior of aluminum in 1 M HCl. The charge transfer resistance increased from 220 Ω cm² without TMP-SMX to 610 Ω cm² when 0.4 g/L of TMP-SMX was present, suggesting the establishment of a shielding TMP-SMX film on aluminium exterior. The current density exhibited a substantial decrease in the presence of TMP-SMX. The alteration in corrosion potential upon the incorporation of TMP-SMX remained below 85 mV, which suggests that TMP-SMX simultaneously retards anodic metal deterioration and cathodic hydrogen evolution. Computational simulation revealed that TMX and SMX maintain nearly parallel orientations with respect to the aluminum surface, suggesting enhanced surface coverage and interactions through heteroatoms and π-electron systems. ∆G⁰ values were negative, signifying that TMP/SMX spontaneously adhered to aluminum. Corrosion rate increased with rising temperature, but decreased with higher inhibitor concentrations. TMP-SMX has the potential to function as an environmentally friendly corrosion inhibitor for aluminium in HCl.