Corrosion Inhibition of Copper in Non-polluted and Polluted Sea Water Using 5-phenyl-1-H-tetrazole

Abstract

Corrosion inhibition of copper in salt water using 5-phenyl-1-H tetrazole (PTAH) was investigated. Experiments were also performed in salt water polluted with thiosulfate or sulfide ions. Potentiodynamic and potentiostatic polarization tests were performed. Polarization tests indicate that the presence of PTAH results in a marked decrease of the anodic current density. The extent of reduction of the current density is increased with the increase of the inhibitor concentration. Standard free energy of adsorption (ΔG°) of -49.15 kJ mol-1 was calculated at 20oC. These values point to chemisorption occurring in the interaction of PTAH and the surface of copper. Activation energies of 71.8 KJ/mol and 17.7 KJ/mol were calculated for the dissolution of copper in the salt solution in the presence and in the absence of PTAH, respectively. The big differences in activation energies indicate the high inhibition efficiency of the PTAH inhibitor. The pollution of the salt solution with thiosulfate or sulfide ions diminishes the passivity of PTAH.