The inhibition effects of cysteine on the corrosion behaviour of copper in 3.5% NaCl solution

Abstract

PurposeThe purpose of this paper is to investigate the inhibition effect of cysteine on the corrosion behaviour of copper in 3.5% NaCl solution with and without cysteine.Design/methodology/approachFor this purpose, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) techniques were used. The surface morphology of the metal sample after exposure to the corrosive medium was investigated by scanning electron microscopy (SEM). The effect of temperature also was studied over the range 298‐328 K. Thermodynamic parameters (ΔG, ΔH and ΔS) were calculated and discussed.FindingsIt was found that cysteine could inhibit the corrosion of copper in 3.5% NaCl solution. Cysteine is an organic corrosion inhibitor for copper, and its molecules are physically adsorbed to form a protective film. Inhibition efficiency increases with decreasing cysteine concentration and the product behaves as an anodic‐type inhibitor.Research limitations/implicationsIn this study, the inhibitory effect of cysteine with temperature change was investigated in environments containing 10−2 M cysteine solution at pH 8.5.Practical implicationsIt will be possible to replace other inhibitors, with cysteine for copper protection in heating/cooling systems at higher temperatures.Originality/valueCysteine acts as an anodic inhibitor especially for copper‐based materials in acidic solution. The interaction between the cysteine molecule and copper in alkaline media has not been investigated in detail. The main objectives of this study was to gain some insight into the protection of copper by cysteine in 3.5% NaCl medium at a pH value of 8.5.