Laminarin and sodium molybdate as efficient sustainable inhibitor for Q235 steel in sodium chloride solution

Abstract

It is of great significance to develop high-efficiency and sustainable inhibitors for Q235 steel under neutral saline conditions. In this study, laminarin (LA) and sodium molybdate (SM) were developed as sustainable corrosion inhibitor for Q235 steel, their inhibition effect and synergistic mechanism in 3.5 wt% NaCl solution was studied by experimentally and theoretically. The results indicated that the complex inhibitor has the highest inhibition efficiency (i.e., 92.75% versus 72.68%) when LA concentration is 0.3 g/L and SM is 0.7 g/L. Electrochemical measurements showed that the LA–SM mixture was anode mixed inhibitor, and confirmed that LA and SM inhibitor have a good synergistic effect. SEM and SECM were conducted to explore the corrosion morphology of Q235 steel surface with LA–SM in NaCl solution. Synergistic mechanism revealed the composite inhibitor could produce multilayer surface protective film presumably leading to an enhanced corrosion inhibition.