Laurus nobilis green inhibitor for patinated bronze protection in sulfate media

The inhibiting effect of Laurus nobilis extract on the corrosion behaviour of patinated bronze was evaluated by means of potentiodynamic polarization, statistical experimental design, Raman spectroscopy and quantum chemical calculations. The patina layer was electrodeposited at the Cu10Sn bronze alloy in aqueous chloride electrolyte under anodic conditions. Electrochemical and Raman characterizations showed the presence of various tin oxides and crystallized as well as porous cuprite in the chloride patina layer. The statistical experimental design was investigated to model the Laurus nobilis inhibition of the patinated bronze in sulfate electrolyte. The plant extract was found to act as mixed type inhibitor. The relatively low protection efficiency was related to the synergetic effect between the experimental parameters. Quantum chemical calculations were performed with the DFT method at the B3LYP/3-21G basis set. The results revealed that the major molecule inhibitor could interact preferentially with tin oxide.