Galvanic Corrosion of Steel–Brass Couple in Petroleum Waste Water in Presence of a Green Corrosion Inhibitor: Electrochemical, Kinetics, and Mathematical View

Control of galvanic corrosion of steel–brass couples in petroleum waste water solution by Curcuma longa was studied at different temperatures, inhibitor concentrations, and velocities using the electrochemical polarization technique. Inhibition efficiency was increased with the increase in inhibitor concentration and decreased with both rises in temperature and solution velocity. Maximum inhibitor efficiency was 94.9% in static solution, higher level of inhibitor concentration and lower level of temperature. The adsorption of Curcuma longa obeyed a Langmuir adsorption isotherm by formation of spontaneous physical layer on the metal surface. Scanning electron microscopy of the metal surface revealed that damage was lower in the presence of Curcuma longa. Activation studied via Arrhenius equation showed that the adsorb layer on the surface increases the energy barrier for corrosive dissolution which is also supported by the higher values of activation energy. Mathematical and statistical analyses were also used as a successful tool to correlate the corrosion rate data with operating conditions.