Temperature Coefficient of Corrosion Inhibition of Steel by Adenine

The inhibition of steel corrosion in 0.5 M sulfuric acid by adenine at different temperatures was shown to follow the Langmuir adsorption isotherm over a wide concentration range (10−5 to 10−3 M). The corrosion potential, corrosion current, corrosion rate, polarization resistance, as well as activation energy and thermodynamic parameters were calculated at different temperatures. From a comparison of the activation energies of uninhibited and inhibited corrosion reactions, the heat of adsorption of adenine may be obtained. The temperature coefficient for corrosion inhibition has a negative value, which may be explained by assuming that the corrosion reaction is no longer the simple metal/acid reaction, but involves the adsorbed species directly.