Experimental and theoretical investigation of novel ammonium-derived dihydroxyl ionic liquid as corrosion inhibitor for mild steel in 1 M HCl: Effects of dihydroxyl and head groups

A novel ammonium-derived dihydroxyl ionic liquid ([C 16 DPOA]Br) and a control ionic liquid ([C 16 DPA]Br) are synthesized to reveal the effect of dihydroxyl and head groups on their inhibition property via the weight-loss method, surface analysis, electrochemical measurements, and adsorption isotherm studies. [C 16 DPOA]Br exhibits the optimal inhibition ability (93.47 %) for mild steel in 1 M HCl in contrast to [C 16 DPA]Br (88.03 %) and the traditional cationic surfactant CTAB (92.34 %). Based on the experimental results, it can be inferred that the short alkyl chain (propyl) impedes the tight alignment of [C 16 DPA]Br on the metal surface and the interactions between hydroxyl and iron atoms enable [C 16 DPOA]Br to overcome the negative effects of the short alkyl chain on the inhibition property. Finally, molecular electrostatic potential (MEP) distribution and molecular dynamics (MD) simulation verify the reactive sites and adsorption capacity of corrosion inhibitors from the microscopic scale, which further confirms the proposed mechanism. This study focuses on the significance of dihydroxyl and head groups on the inhibition property and provides unique insights into the development of efficient ionic liquid corrosion inhibitors.