Inhibitive properties of 2,5-bis(n-methylphenyl)-1,3,4-oxadiazole and biocide on corrosion, biocorrosion and scaling controls of brass in simulated cooling water

• Oxadiazole derivatives were investigated for brass corrosion in simulated cooling water.
• Dependency between inhibition efficiency and structure of inhibitors was explained.
• A synergism effect between oxadiazole derivatives and biocide was obtained.
• Large passivity current plateau was observed in the presence of mixture.
• Electrochemical results were confirmed by SEM/EDX analysis.

2,5-Bis(n-methylphenyl)-1,3,4-oxadiazole with (n = 2,3,4), denoted n-MPOX, have been investigated by using potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) methods, to evaluate the electrochemical behavior of brass in simulated cooling water system. The PP study revealed that oxadiazole inhibited both cathodic and anodic reactions, indicating a mixed type control of inhibition. It was shown that, 3-MPOX as well as 4-MPOX, were the best inhibitors and the inhibition efficiency followed the sequence: 3-MPOX ⩾ 4-MPOX ≫ 2-MPOX. The interference between non-oxidizing biocide CTAB and 3-MPOX and 4-MPOX against corrosion and biocorrosion has also been studied.