Organic corrosion inhibitors for alkaline systems: A case study of 1-benzylimidazole and its mitigation of stainless-steel corrosion in 10 % NaOH + 1 % NaCl solution at 60 oC.

Industrial alkaline descaling of stainless steel is a critical pre-treatment process that employs concentrated NaOH solutions at elevated temperatures for surface cleaning. The aggressive alkaline environment demands inhibitors because it produces a hazardous corrosion condition. Organic inhibitors are preferred because they are inexpensive and environmentally friendly, yet their limited protonation ability prevents them from working in alkaline conditions. The current limitation shows that researchers need to find organic inhibitors that work well under these operating conditions. The present research tested 1-benzylimidazole (BZIM) as a corrosion inhibitor for 316L stainless steel when exposed to 10 % NaOH + 1% NaCl solution at 60 °C. The protective Cr-rich layer on steel surfaces achieved up to 75% inhibition efficiency through BZIM addition, according to EIS and CV and PDP measurements. The system operated at 63% efficiency when exposed to long-term conditions, but it kept 61% stability throughout extended exposure times which demonstrated its ability to protect against harsh alkaline conditions. The atomic force microscopy (AFM) surface characterization showed BZIM effectively reduced corrosion-related microstructural damage which resulted in a more uniform and smooth surface structure. The results were supported by additional computational modeling which demonstrated that BZIM interacts strongly with the metal surface because of its planar aromatic ring structure and negative adsorption energy. The computational predictions showed strong agreement with experimental results, which confirmed the inhibitor's mechanism of action.