Experimental and computational approaches of sustainable quaternary bisammonium fluorosurfactants for corrosion inhibition as protective films at mild steel/H2SO4 interface

Abstract

Three novel quaternary bisammonium fluorosurfactants (FGS-4, FGS-6, and FGS-8) were designed and synthesized using furan-2,5-diylbis(methylene) bis(2-bromoacetate) with N-(3-(dimethylamino)propyl)-1,1,2,2,3,3,4,4,4-nonafluoroalkan-1-sulfonamide through a heterocyclic spacer of 3,3′-((furan-2,5-diylbis(methylene))bis(oxy))bis(3-oxopropan-1-ylium) to connect two fluorocarbon tails. Their corrosion protection characteristics of mild steel/1.0 M H2SO4 solution interface at different temperatures were inspected by electrochemical (PDP and EIS) and weight loss measurements. The PDP plots established that the three-quaternary bisammonium fluorosurfactants are mixed-type inhibitors; EIS experiments exhibited that the as-prepared surfactants possess the superior protection capacities of 93.5 % (FGS-4), 95.5 % (FGS-6), and 96.6 % (FGS-8) at the optimum dose of 2.00 mmol L−1. The Adsorption considerations showed that the three additives demonstrated both the physisorption and chemisorption mechanisms and followed the Langmuir model. Surface morphology investigations indicated that the synthesized fluorocarbon surfactants impeded mild steel corrosion. The relationships between the protection performance of the fluorocarbon surfactants, their molecular configurations, and the adsorption mode were checked by DFT calculations and MD simulations, which confirmed that FGS-8 has a higher protection power than FGS-4 and FGS-6. The current investigation exhibited that quaternary bisammonium fluorosurfactants could be used as eco-friendly, economic, and efficient inhibitors for mild steel corrosion with the probable for extensive applications.