Three imidazole ionic liquids as green and eco-friendly corrosion inhibitors for mild steel in sulfuric acid medium

Abstract

In this paper, the corrosion inhibition performance of eco-friendly corrosion inhibitors 1-propyl-3-methylimidazolium bromide ([PrMIm]Br), 1-aminopropyl-3-methylimidazolium bromide ([APMIm]Br) and 1,4-bis(3-methylimidazolium-1-yl)butane dibromide ([BMImB]Br2) was investigated for mild steel (MS) in H2SO4 medium via experimental and theoretical methods. The results of electrochemical experiments show that the order of their corrosion inhibition is [BMImB]Br2 > [APMIm]Br > [PrMIm]Br. The corrosion inhibition efficiency of [BMImB]Br2, [APMIm]Br and [PrMIm]Br are 92.9%, 88.0%, and 69.6% at the 303 K, respectively. The scanning electron microscope (SEM) morphology test results vividly prove that [BMImB]Br2 has higher corrosion inhibition performance for [APMIm]Br and [PrMIm]Br. Weight loss experiments show that [BMImB]Br2 and [APMIm]Br can still exhibit good corrosion inhibition nature with increasing temperature. Besides, the adsorption of three imidazole ionic liquids on the MS/solution interface is conform to Langmuir single-layer model, and they belong to the physical and chemical adsorption on the MS surface. Theoretical calculations explain their corrosion inhibition mechanism from an atomic or molecule perspective.