Investigation of Organic Complexes of Imidazolines Based on Synthetic Oxy- and Petroleum Acids as Corrosion Inhibitors

The mixture of Synthetic Petroleum Acids (SPA) and oxyacids (OSPA) have been synthesized on the basis of naphthenic-paraffinic hydrocarbons separated from 217-349°C fractions of Azerbaijan oils in the presence of the salts of Natural Petroleum Acids (NPA). The acid number of the obtained (SPA+OSPA) was 165 mgKOH/g, the yield was 40%. Imidazoline derivatives have been synthesized based on the mixture of SPA+OSPA and polyethylene polyamine (PEPA) and their complexes were prepared with CH3COOH and HCOOH. The inhibition action of these complexes on steel corrosion in 1% NaCl solution saturated with CO2 has been studied at 50°C. The results showed that all compounds are good inhibitors and the inhibition efficiencies in the presence of imidazoline derivatives based on SPA+OSPA were 93% and 97% at 25 and 50 ppm, respectively. The activation parameter study suggests the chemisorption for all inhibitors. The obtained values for Gibbs free energy show that the compounds are spontaneously adsorbed on the metal surface by chemisorptions. The image of the steel surface proved that the formed protective film on the electrode surface was stable. The adsorption of the studied compounds on steel surface follows the Langmuir adsorption isotherm.