N-Acetyl cysteine and d-penicillamine as green corrosion inhibitors for copper in 3% NaCl
Ivana Martinović, Zora Pilić, Gloria Zlatić, Vedran Soldo, Martina Šego
Abstract
The corrosion inhibition performance of two amino acid derivatives, N-Acetyl cysteine and D-penicillamine as green corrosion inhibitors of copper in 3% NaCl, in the temperature range of 15–35 °C, was studied by potentiodynamic polarization and impedance measurements. Electrochemical investigations showed the inhibition behaviour of N-Acetyl cysteine and D-penicillamine for copper corrosion with a protection efficiency of ∼ 70%. The adsorption of inhibitors on the copper surface obeys the Langmuir adsorption isotherm and El-Awady kinetic–thermodynamic model. According to the calculated values of Gibbs energy of adsorption (∼−32 kJ mol–1), enthalpy of adsorption (∼−21 kJ mol–1) and entropy of adsorption (42.3 and 34.1 J K–1 mol–1) the adsorption process is exothermic spontaneous chemisorption and physisorption accompanied by an increase in entropy. According to the calculated kinetic activation parameters, the presence of N-Acetyl cysteine and D-penicillamine increases activation energy compared to blank Cu electrode (from 42.3 kJ mol–1 to 56.3 and 56.9 kJ mol–1) indicating strong adsorption of the inhibitor molecules on a copper surface.