Recent advancements in application of Schiff bases as sustainable corrosion inhibitor for mild steel in acid media: a review covering mechanistic, experimental, and computational perspectives

Corrosion of mild steel (MS) starts to degrade MS’s operational features and physical value. However, it can be successfully controlled by the application of corrosion inhibitors (CIs) in the exposure media. However, harmful effects of synthetic inhibitors have restricted its wide use in public-domain applications. Hence, use of sustainable and green corrosion inhibitors is in recent trends. This review provides fundamental knowledge on corrosion, control, inhibition, and mechanisms and further explores Schiff bases (SBs) as sustainable corrosion inhibitors. The SBs are the extremely effective and efficient sustainable CIs. The success of Schiff bases lies in their unique chemical structure. The azomethine (C=N) functional group promotes adsorption of SBs on metal surfaces and makes it easy for them to cover the surface for stopping corrosive molecules. The computational studies like density functional theory (DFT), Monte Carlo (MC) simulation, and molecular dynamics (MD) have also reported that SBs possess great potential to be adsorbed on metal surfaces and hence act as excellent inhibitors. Though SBs works very well against corrosion, they can exhibit poor corrosion performance in some conditions like hydrolytic instability and thermal degradation. These conditions have been discussed in detail along with conflicting reports on adsorption mechanisms, structure performance relationship (SPR) models, and influence of acids on C=N bond. This review covers fundamentals of Schiff bases and mechanistic details about their working mechanisms for MS in acid media. Also, the review explores recent advancements and limitations in the Schiff bases for improved inhibition, sustainability, and technological readiness for industrial control.