Corrosion inhibition of mild steel by new Benzothiazine derivative in a hydrochloric acid solution: Experimental evaluation and theoretical calculations

New Benzothiazine derivative (4-octadecyl-2H-benzo[b] [1,4] thiazin-3(4H)-one) (P3) was synthesized and its inhibitory effect on mild steel in 1 M HCl was evaluated through integrated experimental and computational perspective. Data of detailed study of P3 was collected using gravimetric measurements and electrochemical methods (potentiodynamic polarization (PDP) and EIS techniques). EIS results revealed the augmentation in mild steel corrosion resistance in the presence of P3 by increasing the inhibitor concentration. The highest resistance was achieved at 1 mM concentration. A mixed type behavior of P3 was proved by the PDP measurement. The lowest current density was obtained at 1 mM. SEM images indicated the protective layer growth on steel surface having intact surface morphology and more homogeneity in the presence of P3. In the theoretical approach, a comparative study of P3 with previously achieved results, Benzothiazine derivatives P1 and P2, was widely discussed using the computational methods (i.e., quantum mechanics and MC simulations). [Display omitted]