Copper and
copper alloys are commonly used in industry due to their excellent mechanical properties, making research on the corrosion resistance of
copper of great significance. The corrosion inhibition properties of
2-imidazolidinone and
allantoin for
copper in 3.5 wt % NaCl were studied by
weight loss and electrochemical tests. Changes in the density of the
copper corrosion current and the impedance module indicated that
2-imidazolidinone and
allantoin exhibited cathodic corrosion inhibitors and a valid protective effect. Meanwhile, the
weight loss tests showed that the inhibition efficiency of
2-imidazolidinone and
allantoin at 3 mM reached 98.94% and 97.82%, respectively. The surface physiochemical properties were qualitatively and quantitatively studied by using SEM-EDS, XPS, white light interferometry, and contact angle analysis. The interfacial adsorption behavior revealed by QCM,
synchrotron radiation micro-infrared, and adsorption isotherm analysis indicated that both
imidazole derivatives formed an effective and rigid physical adsorption film and obeyed the Langmuir adsorption model on
copper, while both the mass and thickness of the adsorption film formed by
2-imidazolidinone were higher than those of
allantoin. This study contributed to an in-depth understanding of the interfacial adsorption behavior and corrosion inhibition ability of
2-imidazolidinone and
allantoin and provided guidelines for the design and development of novel heterocycles as potential corrosion inhibitors for
copper in marine environments. In particular,
copper was used as a corrosion inhibitor in seawater storage and transport equipment.