Understanding the Interaction Between Traditional Triazole and Modern β–Pinene Agrochemicals on the Corrosion Behavior of Cobalt in H₂SO₄ Solutions

In this study, the effect of plant-derived β–pinene (BP, CH₂=C(CH₃)–CH₂–C₆H₉) on the corrosion behavior of cobalt (Co) in the presence of 3-amino-1,2,4-triazole (ATA, C₂H₄N₄) and 1H-1,2,3-benzotriazole (BTA, C₆H₅N₃) triazole agrochemicals in 0.5 M and 0.05 M H₂SO₄ acid at 25°C was investigated using electrochemical techniques. The techniques including open circuit potential (EOCP-time), electrochemical impedance spectroscopy (EIS), and Tafel curves were employed to evaluate the corrosion performance. The results revealed that BP exhibited a synergistic effect with both compounds, forming (BTA/BP) Co and (ATA/BP) Co structures that enhanced corrosion protection at acidic concentrations, while significantly reducing the adverse effects of toxic triazoles through interaction with β-pinene. This synergistic interaction was particularly pronounced in 0.5M with BTA, where a stable and protective surface film was formed on the cobalt surface. As a result of this film formation, the corrosion current density decreased significantly from 50 μA/cm² to 9.5 μA/cm², corresponding to approximately 81% inhibition efficiency. Moreover, Inductively Coupled Plasma–Mass Spectrometry (ICP–MS) analysis confirmed that the cobalt ion concentration decreased from 2669 ppb to 132 ppb in 0.5 M H₂SO₄ and from 2350 ppb to 641 ppb in 0.05 M H₂SO₄, indicating a more pronounced inhibition effect at the higher acid concentration. The electrochemical results are in good agreement with the ICP–MS findings, confirmed the formation of a triazole–β-pinene complex and its strong protective performance on the cobalt surface.