THE INHIBITIVE EFFECT OF SOME ALCOHOLS TOWARDS THE CORROSION OF LEAD IN NITRIC-ACID

The inhibitive effect of some alcohols on the corrosion of lead in 4 mol L-1 HNO3 solutions has been studied by both the thermometric and weight loss techniques. Both methods showed that the dissolution rate was dependent on the type, chemical properties and concentration of the alcohol used. All added primary and tertiary alcohols inhibit the dissolution process, but the secondary alcohols act either as inhibitors at low concentrations or as accelerators at high concentrations. The acceleration effect may be attributed to the energy of an exothermic chemical reaction between the alcohol and nitric acid (in presence of lead) exceeding the adsorption energy. The inhibitor efficiency calculated from the thermometric and weight loss methods are in good agreement. The degree of surface coverage, theta, of the adsorbed alcohols was determined from the reaction number, RN, values. The results obey the Langmuir adsorption isotherm.