Impact of N-decyl-nicotineamide bromide on copper corrosion inhibition in acidic sulfate containing environment: Electrochemical and piezoelectrochemical insights

This work investigates the inhibition effect and adsorption properties of a new tailor-made synthesized model molecule of ionic liquids, namely N-decyl nicotinamide bromide [C₁₀Nic]Br in an acidic 0.1 M Na₂SO₄ solution (pH = 2.7) against the corrosion of copper. Electrochemical methods (<i>ac</i> electrochemical impedance spectroscopy and <i>dc</i> potentiodynamic polarization), and piezoelectric method (quartz crystal microbalance with impedance analysis (EQCM-I) were applied to study the corrosion protection performance of the inhibitor. Electrochemical measurements have indicated favorable corrosion inhibition performance of [C₁₀Nic]Br. The corrosion inhibition efficiency increases with the increase of inhibitor concentration, at a [C₁₀Nic]Br concentration of 10^-3 M the efficiency reaches 93 %. The inhibitor adsorption slightly differed from the ideal Langmuir adsorption isotherm. [C₁₀Nic]Br can be considered to be a mixed-type inhibitor. The inhibition efficiency was found to be time-dependent. In the presence of the highest 10^-3 M inhibitor concentration the formation of the maximum protective effect of the inhibitor layer takes several hours, the maximum value of polarization resistance was 8.5 kΩ cm² after 5 h. The copper dissolution and the inhibitor adsorption were also monitored by real-time changes in mass and viscoelasticity determined by QCM-I. It was obtained that the inhibitor adsorption on the copper surface leads to a decrease in copper dissolution and an increase in viscoelasticity. The layer on the copper surface becomes softer due to the complex between the inhibitor and the corrosion products on the surface.