Corrosion Inhibition Mechanism of Durian Peel and Stone Extract for Copper in Sulphuric Solution

Durian peel and stone extract (DPSE) was prepared through ethanol extraction, in which 5-amino-1H-imidazole-4-carboxamide, 3,5-dihydroxybenzoic acid and 3-(benzyloxy)butane-1,2,4-triol were the main components. The corrosion inhibition effect of DPSE on copper in 0.5 mol/L H₂SO₄ solution was evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy and morphology observation. The results showed that DPSE could inhibit both cathodic and anodic reactions, reduce the corrosion current density and increase the interfacial charge transfer resistance of copper immersed in H₂SO₄ solution. The maximum inhibition efficiency could reach 92.6% with the DPSE concentration of 600 mg/L. DPSE effectively adsorbed on copper surface, which conformed to Langmuir isotherm. The outcomes of theoretical calculations revealed that three main components in DPSE favored to exhibit the parallel adsorption configuration on Cu (111) plane.