EFFECT OF TEMPERATURE ON THE ACIDIC DISSOLUTION OF COPPER IN THE PRESENCE OF AMINO-ACIDS

The corrosion behaviour of a copper electrode in a 1 M HCl solution ha s been studied potentiokinetically at different temperatures ranging f rom 25 to 55-degrees-C. The inhibition efficiency of four amino acids was then tested for three concentrations in the range 10(-5)-10(-3) M. The amino acids, in the presence of HCl solution, caused a shift, mai nly in the anodic direction of the corrosion potential at low current densities as well as the linear part of the cathodic Tafel line. The p rotection efficiency of each amino acid was calculated for different t emperatures and concentrations. The amino acids act as a corrosion inh ibitor in HCl solution through adsorption on the copper surface. The k inetic results, operating through a compensation effect, could well ac count for the variation of the inhibiting capacities of the various am ino acids. The results reported in this paper elucidate the effect of temperature and the molecular structure on the inhibition efficiency. alpha-alanine was the most efficient of the four amino acids for inhib iting the corrosion of copper in HCl solution. Thermodynamic parameter s for adsorption of the amino acids are calculated.