Investigation of Inorganic Complexes of Amidoamines Synthesized from Synthetic Oxy- and Petroleum Acids as Corrosion Inhibitor

Amidoamines have been synthesized based on the mixture of synthetic petroleum and oxy acids (SPA + OSPA) and polyethylene polyamine (PEPA). Physical and chemical indices of amidoamines have been identified. Complexes have been prepared from the amidoamine and HCl (Example 1), H3PO4 (Example 2), HNO3 (Example 3) in ratio 1:1. The kinetic effect of steel corrosion in 1% NaCl solution saturated with CO2 has been studied in ACM Gill AC potentiometer, at 50°C. Investigation was conducted at 25 and 50 ppm of each complex. It was found that, in Example 1 at 25 ppm after 20 hours of research the protection effect was 97.5%, at 50 ppm 97.3%. In Example 2 at 25 and 50 ppm corrosion protection were 92% and 90.4% after 20 hours of research. In Example 3 at 25 and 50 ppm after 20 hours of research protective effects were 97.5 and 97.3%. It was determined that, amidoamine derivatives obtained from SPA + OSPA and PEPA, at 25 ppm was the best result-98.3%. By Calculated Gibbs free energy and the image of the surface of used electrode it has been proved that, a complex in different concentrates easily was exposed to chemisorption on metal surface. Therefore protective film formed on the surface was stable.