Investigating the efficacy of phenolic Schiff bases as corrosion inhibitors for mild steel in acidic environments: Integrating experimental and theoretical approaches (Part B)

Abstract

Our research employs a holistic methodology to assess the efficacy of a series of phenolic Schiff bases as corrosion inhibitors for mild steel in a 1 M HCl solution. Through complementary studies, we aim to unravel the corrosion inhibition mechanism by investigating neutral, protonated, and complex forms of inhibitors using advanced computational and statistical methods. This initial investigation specifically involves evaluating the effectiveness of two phenolic Schiff bases through weight loss tests (WL) and electrochemical techniques. The study focuses on the corrosion inhibitory properties of two phenolic Schiff bases, namely 4,4′-((1E,1′E)-(ethane-1,2-diylbis(azaneylylidene))bis(methaneylylidene))diphenol (PSB7) and (1E,1′E)-N,N'-(ethane-1,2-diyl)bis(1-(4-nitrophenyl)methanimine) (PSB8), on mild steel (MS). Results from weight loss and electrochemical methods indicate that inhibition efficiency improves with decreasing temperature and increasing inhibitor concentration, reaching 94 % (for PSB7) and 93 % (for PSB8) at 303 K and 1 × 10−3 M, respectively. Consequently, both PSB7 and PSB8 function effectively as inhibitors in a mixed form. The adherence of both inhibitors to the surface follows the Langmuir adsorption isotherm model. Additionally, SEM and EDS experiments provide evidence of adsorption on the surface. The findings from Density Functional Theory (DFT) and Molecular Dynamic Simulations (MDS) consistently match the actual data, maintaining the order of inhibition efficiency (PSB7 > PSB8).