SPECTROELECTROCHEMICAL STUDY OF THE CORROSION OF A COPPER ELECTRODE IN DEAERATED 1.0 M HCL SOLUTIONS CONTAINING FE(III) - EFFECT OF THE CORROSION-INHIBITOR BENZOTRIAZOLE

The corrosion rate of a copper electrode is deaerated 1. 0 M HCl by Fe(III) ions, in the absence and presence of benzotriazole (BTAH), has been evaluated through weight-loss experiments using a rotating disk electrode (RDE). The corrosion process is controlled by transport of the Fe(III) ions to the electrode surface both in the absence and presence of BTAH. The inhibiting action is initiated at BTAH concentrations around 10 mM and the Langmuir adsorption isotherm is obeyed in the BTAH concentration range from 10 to 45 mM with an apparent equilibrium adsorption constant of 10 M** minus **1. Above this concentration, the Langmuir plot is not obeyed due to the formation of a multilayer. The surface films formed during the corrosion process have been investigated by in situ and ex situ fluorescence and Raman spectroscopy and characterized as being composed of the polymeric left bracket Cu(I)BTA right bracket complex and left bracket Cu(I)ClBTAH right bracket //4, the former as an inner layer response for the corrosion inhibition process.