Anticorrosion of Copper by Turtle Shape-Like Long Fatty Chain Linker-Included Bis-Schiff Base Molecules Synthesized from a Natural Analogue of Vanillin

Copper and alloys suffer from severe corrosion during acid picking and acid cleaning in the industry. In this study, the corrosion inhibition of copper in sulfuric acid solution was inspired by the turtle shape-like bis-Schiff bases bearing fatty chain linkers (BSBs 1–3), which were synthesized from a natural analogue of vanillin under mild conditions. The chemical structures of the BSBs were fully identified, and the presence of hydrogen bonding in the BSBs was confirmed. The target BSBs display affinity to the copper surface using the Schiff base parts (like turtle feet), and thus, the fatty linkers in the BSBs could resist aggressive species invading the copper surface (like turtle shell). The corrosion resistance and corrosion inhibition mechanism of BSBs for copper were investigated experimentally in 0.5 M H₂SO₄ solution. The results show that target BSBs might significantly inhibit the corrosion of copper in acid solution. The corrosion inhibition efficiencies of BSBs 1–3 were maximized at a concentration of 1.00 mM under 298 K, which reached 97.99, 96.22, and 94.58%, respectively. It is shown that the corrosion inhibition effect of the BSBs for copper increased with an increase in the length of fatty linkers, which was consistent with the order of hydrogen bonding strength. The adsorption and anticorrosion mechanisms of the target molecules for copper were analyzed. The results presented in this study could provide an experimental insight for engineering new efficient, low-cost, and environmentally friendly corrosion inhibitors for copper through simple preparation using natural compounds as starting molecules.